Subjects

-N 0-9

532 Fluid Mechanics

	A Note on Unsteady Flow of a Dusty Viscous Liquid in a Channel and a pipe Author : Srivastava, L.P. ;Dube, S.N. Source : Defence Science Journal ; Vol:22(3) ; 1972 ; pp 195-198 Subject : 532.542 Fluid Dynamics;532 Fluid Mechanics Keywords : Fluid particles ;Dust particles Abstract : The note considers the flow of a viscous liquid with uniform distribution of dust particles in a channel and a circular pipe under the influence of pressure gradient varying linearly with time. It is found that the velocity of fluid particles is more than that of dust particles.
	Flow of an Elastico-viscous Fluid Past an Infinite Plate with Variable Suction Author : Murthy, Ch. V. Ramana ;Kulkarni, S. B. ;Singh, B. B. Source : Defence Science Journal ; Vol:57(4) ; 2007 ; pp 403-410 Subject : 532 Fluid Mechanics;53 Applied Physics Keywords : Elastico-viscosity;Second-order fluid;Retarded history;Suction parameter Abstract : Unsteady state flow of an incompressible elastico-viscous fluid of second-order type past an infinite vertical porous flat plate by considering uniform and variable suction normal to the plate has been studied and an exact solution is obtained for the velocity field. In the present situation, only two prescribed boundary conditions are available while the governing equation of motion is of third-order due to the presence of elastico-viscosity parameter. The concept following Walters has been used for a much more meaningful solution. The results for the velocity distribution and skin friction have been analysed and discussed for different values of the parameters encountered in the governing equation of motion and skin friction on the plate. It is found that the effect of elastico-viscosity and suction has significant contribution on the backflow at the wall.
	Turbulence Measurements in Swirling Flows Author : Marwah, I.J. ;Chopra, M.G. Source : Defence Science Journal ; Vol:31(4) ; 1981 ; pp 261-275 Subject : 532 Fluid Mechanics Keywords : Recirculation zone ;Diffuser angle;Turbulence intensity;Anemometer;Divergent passage Abstract : Investigation have been conducted to find out the region of high turbulent intensities in a swirling jet passing through a divergent passage. A hot wire anemometer is used to measure the turbulence intensity using a four position method. It has been concluded that the jet spreads with increasing diffuser angle and the region of high turbulent intensity also spreads. The high turbulence intensity region lies around the recirculation zone and it decays rapidly along the main flow direction.
	Flow of an Oldroyd Fluid Past a Sphere at Low Reynolds Number Author : Chaudhary, R.C. ;Verma, P.D. Source : Defence Science Journal ; Vol:31(3) ; 1981 ; pp 251-254 Subject : 532 Fluid Mechanics Keywords : Drag ;Newtonian fluid;Asymptotic technique Abstract : Slow motion of an Oldroyd fluid past a sphere has been investigated using matched asymptotic technique. The drag experienced by the sphere has been obtained form the solution. To the first order in tau ( a non-Newtonian parameter), the drag is unchanged from its value for Newtonian fluid but to the second order the drag is decreased.
	Exact Solutions of an Incompressible Fluid Flow of Second Order by Forced Oscillations on the Porous Boundary Author : Ramana Murthy, Ch. V.;Kulkarni, S. B.;Singh, B. B. Source : Defence Science Journal ; Vol:57(2) ; 2007 ; pp 197-209 Subject : 532 Fluid Mechanics;53 Applied Physics Keywords : Elastico-viscous fluid;Second-order fluid;Retarded history;Porous media;Fluid flow Abstract : Exact solution of an incompressible fluid of second-order type by causing forced oscillations in the liquid of finite depth bounded by a porous bottom has been obtained. The results presented are in terms of nondimensional elastico-viscosity parameter (b) which depends on the non-Newtonian coefficient and the frequency of excitation (s) of the external disturbance while considering the porosity (K) of the medium. The flow parameters are found to be identical with that of Newtonian case as b ® 0 and K ® ¥. It is seen that the effect of b and the porosity of the bounding surface has significant effect on the velocity parameter. Further, the nature of the paths of the fluid particles have also been studied with reference to b and the porosity of the bounding surface.
	Charge Transfer in Light Effect Under Visible Radiation in an Ozoniser Discharge Author : Salvi, S.V.;Pimpale, Sushama S. Source : Defence Science Journal ; Vol:56(5) ; 2006 ; pp 715-720 Subject : 53 Applied Physics;532 Fluid Mechanics Keywords : Electromagnetic radiation;Ozoniser discharge;Light-effect pulse height;Discharge count;Charge transfer Abstract : Two fresh discharge vessels (1 and 2) of Siemen’s ozoniser type having the same height but different surface-to-volume ratios have been fabricated by enclosing argon at 10 mm mercury. By immersing these in electrolytic solution and by subjecting these to a definite high 50 Hz ac voltage, the discharge count rates in dark (Cf )D and under light (Cf )L have been determined using a scaler held at different bias-voltages. The plot of the ratio (C1f / C2f )D and (C1f / C2f )L of discharge counts versus pulse height (bias-voltage) shows that this ratio for a constant potential of 3.5 kV (rms) is initially large in value, then rapidly decreases to a minimum. It is also observed that more is the surface-to-volume ratio, more is the magnitude of net effect of irradiation. Further, the pulse height analysis shows that the charge carried by the pulses to the electrodes (charge transfer) decreases under illumination. A possible mechanism to explain the net effect of the discharge current ratio in the light of pulse height measurements is discussed.
	Determination of Optimum Non Slender Bodies of Revolution having Minimum Drag in Free Molecular Flow Author : Tawakley, V.B.;Jain, S.C. Source : Defence Science Journal ; Vol:21(4) ; 1971 ; pp 227-234 Subject : 532.542 Fluid Dynamics;532 Fluid Mechanics Keywords : Cusp ;Optimum Body Shape;Temperature Ratio;Molecular Flow Region Abstract : The problem of determining the body of revolution having minimum drag has been considered in the free molecular flow region under given integral constraints and in combination with the calculus of variations. It has been shown that for a given surface area or volume, the optimum shape is sharp nosed if diameter is prescribed and it is flat nosed if the length is prescribed. When the volume and thickness are known the optimum shape has cusp at the origin whereas if surface area and diameter are given the optimum body shape is independent of the value of k, a parameter dependent upon the temperature ratio and the speed ratio.
	Unsteady Flow of a Dusty Viscous Liquid Through Circular Cylinder Author : Rao, Siva ;Samba, P. Source : Defence Science Journal ; Vol:19(2) ; 1969 ; pp 135-138 Subject : 532 Fluid Mechanics Keywords : Analytical expressions ;Laminar flow;Dust particles Abstract : The laminar flow of an unsteady viscous liquid with uniform distribution of dust particles through a circular cylinder under the influence of exponential pressure gradient has been investigated. Two interesting cases have been discussed and analytical expressions for velocities of fluid and dust particles are obtained.
	Analysis of Titanium-matrix Orthotropic Cylindrical Shell Subjected to Thermomechanical Loading Author : Reddy, M.C.S.;Rama Murty, G. Source : Defence Science Journal ; Vol:56(5) ; 2006 ; pp 701-714 Subject : 53 Applied Physics;532 Fluid Mechanics Keywords : Titanium-matrix composites;Orthotropic cylindrical shells;Unconstrained effects;Thermomechanical loading;Deformation Abstract : A titanium-matrix orthotropic cylindrical shell with the principal direction of orthotropy following a parallel constant angle helix, has been studied when it is subjected to uniform loading conditions of internal pressure, axial load and pure twisting moment. Nondimensional parameters pertaining to loading and deformations have been calculated and results plotted. The results obtained can be usefully applied in robotic actuators where lightweight considerations with high strength are of prime importance. The study is further extended to investigate the effect of temperature on the deformations. Through parametric studies, deformation patterns are calculated and plotted that are unique to orthotropy. In most of the cases, it is observed that deformation patterns are same, but deformation is increasing with temperatures.
	Free Convection Flow with Constant Heat Sources in a Porous Channel Author : Agarwal, R.S. ;Arora, S.S. Source : Defence Science Journal ; Vol:31(1) ; 1981 ; pp 45-52 Subject : 532.542 Fluid Dynamics;532 Fluid Mechanics Keywords : Free convection effects ;Heat source parameter Abstract : The effect of constant heat sources on fully developed free convection flow of a viscous fluid in a porous channel oriented in the direction of the body force has been studied when the walls are maintained at constant temperatures. It has been found that both the velocity and temperature depend on the heat source parameter alpha and the dimensional group Q representing the free convection effects.
	Hydraulic analogy for isentropic flow through a Nozzle Author : Seshadri, V. ;Rao, V.V.R.;Rao, J.S. Source : Defence Science Journal ; Vol:33(2) ; 1983 ; pp 97-111 Subject : 532.5 Hydrodynamics;532 Fluid Mechanics Keywords : Nozzle ;Hydraulic Analogy;Modelling Aspects Abstract : Modelling aspects of isentropic compressible gas flow using hydraulic analogy are discussed. subsonic and supersonic flow through a typical nozzle are simulated as free surface incompressible water flow in an equivalent 2-D model on a water table. The results are first compared for the well known classical analogy in order to estimate experimental errors. Correction factors for pressure and temperature, to account for non ideal compressible gas flow are presented and the results obtained on the water table are modified and compared with gas dynamic solution. Within the experimental errors, it is shown that the hydraulic analogy can be used as an effective tool for the study of two dimensional isentropic flows of gases.
	Hydromagnetic Couette Flow with Time Dependent Suction or Injection Author : Srivastava, R.B. Source : Defence Science Journal ; Vol:21(4) ; 1971 ; pp 249-252 Subject : 532 Fluid Mechanics;532.542 Fluid Dynamics Keywords : Prandtl Number ;Hydromagnetic Parameter Abstract : Hydromagnetic couette flow of an electrically conducting viscous and incompressible fluid in a transverse magnetic field is studied when the plates are non magnetic and non conducting. The suction velocity is assumed to be varying as [(time)- Sup 1/2] . The analysis is valid for small values of hydromagnetic parameter[(Mt)/Sup1/2 ]and for magnetic Prandtl number unity.
	Magneto Hydrodynamic Flow of a Viscous Incompressible Fluid Between a Parallel Flat Wall and a Long Wavy Wall Author : Bathaiah, D. ;Reddy, N. Bhaskara Source : Defence Science Journal ; Vol:31(4) ; 1981 ; pp 315-322 Subject : 532.542 Fluid Dynamics;532 Fluid Mechanics Keywords : Temperature distribution ;Frequency parameters;Coefficient of skin friction;Velocity distribution Abstract : Magneto-hydrodynamic flow of a viscous incompressible slightly conducting fluid between a parallel flat wall and a long wavy wall has been studied. The velocity distribution, the coefficient of skin friction and temperature distribution has been evaluated. The effects of magnetic, suction and frequency parameters are investigated on velocity, the coefficient of skin friction and temperature distribution.
	The non-uniform rotation of a non-Newtonian liquid filled in between two coaxial cylinders of infinite length Author : Mithal, K.G. Source : Defence Science Journal ; Vol:10(3) ; 1960 ; pp 228-236 Subject : 532 Fluid Mechanics;53 Applied Physics Keywords : Non-uniform rotation ;Non-Newtonian liquid filled ;Co-axial cylinders Abstract : The non-uniform rotation of a non-Newtonian, incompressible liquid contained between two co-axial cylinders of infinite length is considered. Initially, the outer cylinder is rotating with constant angular velocity. When the inner cylinder is at rest, the liquid is supposed to be on steady motion but, when it is given an impulsive twist, it also begins to rotate with a constant angular velocity and the motion of the liquid becomes unsteady. The various states of motion of the liquid are discussed.
	On the Class of Exact Solutions of an Incompressible Second-order Fluid Flow by Creating Sinusoidal Disturbances Author : Ramana Murthy, Ch. V. ;Kulkarni, S. B. Source : Defence Science Journal ; Vol:56(5) ; 2006 ; pp 733-742 Subject : 53 Applied Physics;532 Fluid Mechanics Keywords : Elasticoviscous fluid;Second-order fluid;Retarded history;Porous media;Fluid flow;Heat transfer Abstract : Exact solution of an incompressible fluid of second-order by causing disturbances in the liquid, which is initially at rest due to bottom oscillating sinusoidally, has been obtained in this study. The results presented are in terms of nondimensional elasticoviscosity parameter (b) which depends on the non-Newtonian coefficient and the frequency of excitation of the external disturbance while considering the porosity (K) of the medium. The flow parameters are found to be identical with that of Newtonian case as b ® 0 and K ® ¥.
	Steady Flow of Micropolar Incompressible Fluid between Two Parallel Porous Plants Author : Moizuddin ;Rao, G.Teeka Source : Defence Science Journal ; Vol:30(3) ; 1980 ; pp 105-112 Subject : 532 Fluid Mechanics;532.542 Fluid Dynamics Keywords : Micropolarity parameter ;Perturbation method ;Micropolar incompressible fluid Abstract : Steady flow of a micropolar incompressible fluid between two parallel porous plates y=0 and y=h is studied by perturbation method. Injection velocity at y=0 is V/sub 1/ and at y=h the suction velocity is V/sub 2/. The behaviour of the various flow various is investigation for varying values of the micropolarity parameter k/mu. It is observed that the longitudinal velocity is more at the lower plate and less at the upper plate than in the non-polar case. It is also observed the wall friction is more at both plate when compared to the non-polar case.
	Dusty Viscous Flow Through a Cylinder of Rectangular Cross Section Under Time Dependent Pressure Gradient Author : Rukmangadachari, E. Source : Defence Science Journal ; Vol:31(2) ; 1981 ; pp 143-153 Subject : 532 Fluid Mechanics Keywords : Incompressible fluid ;Drag;Flux Abstract : Unsteady laminar flow of a dusty, viscous, incompressible fluid through a cylindrical tube of rectangular cross-section is studied when the pressure gradient varies (i) exponentially and (ii) harmonically w.r.t. time. The velocity fields for the fluid and the dust particles have been obtained. Results in limiting cases are derived. Flux and drag have been calculated. Flow through a tube of square section and flow between parallel plates have been obtained as special cases.
	Propagation of Strong Magneto-radiative Plane Shock Wave in a Self-gravitating Exponentially-decreasing Medium Author : Ganguly, Ashok;Sharma, Pankaj Source : Defence Science Journal ; Vol:57(1) ; 2007 ; pp 123-131 Subject : 53 Applied Physics;532 Fluid Mechanics Keywords : Plane shock wave;Gravitation, Radiation flux;Magneto-radiative shock waves;Exponentially decreasing medium;Wave propagation;Fluid flow Abstract : A self-similar theoretical model of propagation of strong plane shock waves in an inhomogeneous, magneto-radiative, self-gravitating atmosphere in the direction of decreasing density is considered. The results discussed depend upon the variations of the flow variables which are displayed graphically and the influences of the gravitation and radiation flux have been studied.
	On the constitutive relation for a class of reinerrivlin fluids Author : Kapur, J. N.;Gupta, R. C. Source : Defence Science Journal ; Vol:16(1) ; 1966 ; pp 21-24 Subject : 532 Fluid Mechanics Keywords : Fluid mechanics;Reiner-Rivlin fluids;Viscosity;Stress;Strain Abstract : For a class of Reiner-Rivlin fluids characterised by the relation T =µ0I+µ1 D+µ2D2 ……µnDn where T, D and I are the stress, rats of strain and unit matrices respectively, restrictions on the phenomenological coefficients µ0, µ1, µ2, µn ……. where they (i) are constants and (ii) accept power-series expansions, have been obtained so that the dissipation function is non-negative for all possible rates of deformation.
	Flow of a Dusty Gas Between Two Parallel Plates One Stationary and Other Oscillating Author : Bhattacharyya, P. ;Mitra, P. Source : Defence Science Journal ; Vol:31(3) ; 1981 ; pp 211-223 Subject : 532 Fluid Mechanics Keywords : Velocities of dusty gas ;Mass concentration;Incompressible viscous dusty gas Abstract : The solution for the flow of an incompressible viscous dusty gas, induced by two infinitely extended parallel plates when the lower plate is at rest and the upper plate begins to oscillate harmonically in its own plane, is obtained, It is found that (i) with the increase in the mass concentration both the velocities of the dusty gas and the particle decreases, (ii) the velocity of the dusty gas increases and that of the particle decreases with the increase in neta.
	Flow of Power Law Fluids between Two Rotating Co Axial Cones Author : Dikshit, R.R. Source : Defence Science Journal ; Vol:16(2) ; 1966 ; pp 89-96 Subject : 532 Fluid Mechanics Keywords : Fluids flow;Newtonian fluid Abstract : The problem of fluids flow between two coaxial cones has important applications in the theory of hydrodynamic lubrications and in the measurement of viscosity coefficients. In a recent paper Rathy has discussed the flow of a Newtonian fluid between two coaxial rotating cones with a common vertex under a radial force. In the present paper an exact analytical solution of the flow behaviour of power-law fluids between two coaxial rotating cones under the action of a radial force, has been obtained.
	Oscillating plate temperature effects on mixed convection Flow past a semi infinite vertical Porous Plate Author : Vighnesam, N. V.;Ray, S. N. ;Soundalgekar, V. M. Source : Defence Science Journal ; Vol:51(4) ; 2001 ; pp 415-418 Subject : 532 Fluid Mechanics Keywords : Semi infinite verticle plate;Oscillating plate;Steady mixed convection flow;Fluid flow Abstract : "The effects on mixed convection flow past a semi-infinite vertical porous plate have been studied when the plate temperature oscillates about a non-zero mean. Only out-of-phase component of unsteady part of the temperature is shown graphically. The results show that there is always a phase-lead in the rate of heat transfer at small values of w. "
	Finite Element Analysis of Collapse of Metallic Tubes Author : Gupta, P. K.;Gupta, N. K.;Sekhon, G. S. Source : Defence Science Journal ; Vol:58(1) ; 2008 ; pp 34-45 Subject : 53 Applied Physics;532 Fluid Mechanics Keywords : Metallic tubes;Quasi-static loading;Mode of deformation;FORGE2;Energy-absorbing devices Abstract : Quasi-static axial and lateral compression tests were conducted on aluminium tubes of circular, rectangular, and square cross sections on a universal testing machine (Instron model 1197). During the compression process, different tubes were collapsed in different modes of collapse. These compression processes were also modelled using FORGE2 finite element code. The code has the capabilities of automatic mesh generation, modelling of die, creation of material data file, carrying out the finite element computations, and post-processing of results. The deforming tube material was modelled as rigid-visco-plastic. Development of different modes of collapse was investigated experimentally and computationally. The experimental load-compression curves and deformed shapes are compared with the computed results and found in good agreement. It is found that the proposed finite element models of the different compression processes are capable of predicting the modes of collapse.
	Flow of a Dusty Viscous Liquid Through Rectangular Channel Author : Singh, B.M. Source : Defence Science Journal ; Vol:22(3) ; 1972 ; pp 153-158 Subject : 532.542 Fluid Dynamics;532 Fluid Mechanics Keywords : Hilbert transform technique ;Mellin transforms Abstract : An exact solution of triple integral equations involving inverse Mellin transforms has been obtained by finite Hilbert transform technique in this paper. The advantage of the above mentioned technique is that the solution obtained is simple than that given by Srivastav & Parihar. Finally the application of triple integral equations to two dimensional electrostatic problem has also been discussed.
	Convective MHD Oscillatory Flow past a Uniformly Moving Infinite Vertical Plate Author : Ahmed, N.;Das, U.N. Source : Defence Science Journal ; Vol:42(1) ; 1992 ; pp 53-57 Subject : 532 Fluid Mechanics;53 Applied Physics Keywords : Magnetohydrodynamic flow;Infinite vertical plate;Suction velocity Abstract : The convective magnetohydrodynamic flow past a uniformly moving infinite vertical plate, with the magnetic field and the suction velocity applied normal to the plate has been analysed. Presence of heat source or sink has also been considered. The findings are expected to throw light on some problems of defence applications in the areas of aeronautical designs and also flow and heat transfer problems of a chemically reacting fluid.
	Free Convection Plow of Old royd Liquid Past A Hot Vertical Porous Plate Author : Mishra, Shankar Prasad Source : Defence Science Journal ; Vol:16(1) ; 1966 ; pp 17-20 Subject : 532 Fluid Mechanics Keywords : Fluid mechanics;Oldroyd elastico-viscous liquid;Fluid velocity Abstract : The problem of flow of an elaatico-viscous liquid past a hot vertical porous flat plate has been considered by taking into account the effect of free convection when a body force 'g' acts in a direction opposite to that in which flow takes place. Numerical calculations have been made to study the effect of free convection and elasticity of the fluid on the fluid velocity. The fluid velocity and the skin-friction both increase with the Grashof number. The skin-friction is not affected by the elastic elements. The fluid velocity increases with the relaxation time but decreases with the increase in retardation time.
	Two Dimensional unsteady Free Convective Flow of a Viscous Incompressible Fluid through a Rotating Porous Medium Author : Baghel, R.C.;Kumar, G.;Sharma, R.G. Source : Defence Science Journal ; Vol:42(1) ; 1992 ; pp 59-62 Subject : 53 Applied Physics;532 Fluid Mechanics Keywords : Two dimensional free convective flow;Vertical plane surface Abstract : An exact analysis of the effects of unsteady two-dimensional free convective flow during the motion of a viscous incompressible through a highly porous medium was undertaken. The porous medium is bounded by a vertical plane surface of constant temperature. The surface absorbs the fluid with a constant velocity and the free stream velocity of the fluid vibrates at a mean constant value. The analytical expressions for the velocity of the fluid are presented in the paper. The effects of rotation and permeability parameters on the axial and transverse components of velocity are discussed with the help of graphs.
	Steady Flow of Two Conducting Incompressible and Immiscible Fluids Between Two Conducting Plates under Closed Circuit Conditions Author : Prasad, R. ;Shukla, J.B. Source : Defence Science Journal ; Vol:19(1) ; 1969 ; pp 13-20 Subject : 532 Fluid Mechanics Keywords : Skin friction ;Parallel plates;Immiscible fluids Abstract : This paper discusses the flow of two conducting, viscous, incompressible and immiscible fluids between two conducting parallel plates in presence of an applied transverse magnetic field under general electrical loading conditions. It has been shown that the flow fluxes of the two fluids, the interface velocity and the skin friction on the two plates with the increase of the total current.
	Effect of boundary conditions on freezing in porous media Author : Basu, Rahul Source : Defence Science Journal ; Vol:54(3) ; 2004 ; pp 317-328 Subject : 532 Fluid Mechanics Keywords : Heat and mass transfer;Boundary conditions;Phase interface;Advanced nimonics;Boundary functions Abstract : "This paper examines a model for coupled heat and mass transfer for freezing in a porous media with Dirichlet and convective boundary conditions. Variables include porosity, heat transfer coefficients, thermal and mass diffusivity, density, latent heat, and boundary temperatures. A simulation for the slab illustrates the appearance of undercooling. A stability criterion for the phase interface is linked with well-known metallurgical parameters like undercooling and freezing rate. A possible mechanism for freckling in ingots of niobium-rich superalloys is examined. It has been shown that heat and mass transfer balance at the interface can affect stability. The effect of boundary conditions on the velocity of freezing is computed for some cases, including the self-freezing process. "
	Tensile Strength of Snow using Centrifugal Technique Author : Upadhyay, Agraj;Chandel, Chaman;Joshi, S. K. Source : Defence Science Journal ; Vol:57(6) ; 2007 ; pp 787-795 Subject : 53 Applied Physics;532 Fluid Mechanics Keywords : Tensile strength;Centrifugal machine;Microstructural parameters;Failure stress;Probability distribution;Snow studies Abstract : Tensile strength of snow was determined using indigenously developed automated centrifugal machine. Processed snow (sintered at -20 °C for 4 days) samples of dia: 65 mm and height:130 mm were tested using this machine.The experiments were conducted on sieved snow at four temperature levels of 0 °C, -3 °C, -6 °C and -9 °C at density ranging from 200-460 kg/m3. Results of these experiments have been compared with the earlier suggested models. Probability distribution of snow strength on the basis of current experimental data has also been presented.
	Oscillatory Free Convection from a Rotating Disk Author : Bhattacharjee, R.C. Source : Defence Science Journal ; Vol:27(3) ; 1977 ; pp 129-134 Subject : 532 Fluid Mechanics Keywords : Kraman Pohlhaulsen;Rossby number;Angular velocity ;Rotating Disk Abstract : Free convection flow from an infinite disk, when both the disk and the surrounding fluid rotate with the same angular velocity about the same vertical axis has been considered. The disk is maintained at an axisymmetric nonuniform temperature distribution which oscillates about a steady nonzero mean. The temperature of the fluid at large distance from the disk is taken to be constant. The problem is formulated for small values of the reduced frequency which is the ratio of the frequency of oscillations of the temperature of the disk to the angular velocity of the fluid. The equations are integrated by Kraman-Pohlhaulsen method for a fluid of Prandt1 number unity. The solution holds good when the Rossby number and the reduced frequency are of the same order.
	Creep Transition in a Thin Rotating Disc with Rigid Inclusion Author : Gupta, S. K.;Pankaj Source : Defence Science Journal ; Vol:57(2) ; 2007 ; pp 185-195 Subject : 53 Applied Physics;532 Fluid Mechanics Keywords : Creep stress;Thin rotating disc ;Stress ;Strain ;Rotors ;Turbines ;Creep transition ;Solid mechanics Abstract : Creep stresses and strain rates have been obtained for a thin rotating disc with inclusion using Seth’s transition theory. Results have been discussed numerically and depicted graphically. It has been observed that radial stress has maximum value at the internal surface of the rotating disc made of incompressible material as compared to circumferential stress and this value of radial stress further increases with the increase in angular speed. Strain rates have maximum values at the internal surface for compressible material. Rotating disc is likely to fracture by cleavage close to the inclusion at the bore.
	Viscous Liquid Layer Sandwiched Between Two Generalized Thermoelastic Halfspaces Author : Harinath, K.S. Source : Defence Science Journal ; Vol:31(3) ; 1981 ; pp 245-250 Subject : 532 Fluid Mechanics Keywords : Liquid layer ;Effect of gravity Abstract : A detailed investigation of waves in a viscous liquid layer of finite thickness sandwiched between two generalized thermoelastic halfspaces reveals the fact that for realistic situations one has to consider the effect of gravity at least in the liquid layer.
	Secondary Flow and Heat Transfer of Two Incompressible Immiscible Fluids Between Two Parallel Plates in a Rotating System Author : Narayana, N. Venkata ;Rao, V.V.Ramana Source : Defence Science Journal ; Vol:31(3) ; 1981 ; pp 181-198 Subject : 532 Fluid Mechanics Keywords : Ratio of viscosities ;Secondary motion;Constant pressure gradients Abstract : When a straight channel formed by two parallel plates, through which two immiscible fluids are flowing under constant pressure gradients is rotated about an axis perpendicular to the plates, secondary motion is set up. The secondary motion is analysed in detail for constant angular velocity ohm', lambda the ratio of their viscosities. The associated heat transfer problems, when the plate temperatures are equal and different, have also been studied.
	Flow of a Dusty Viscous Liquid Through Rectangular Channel Author : Reddy, Y.B. Source : Defence Science Journal ; Vol:22(3) ; 1972 ; pp 149-152 Subject : 532.542 Fluid Dynamics;532 Fluid Mechanics Keywords : Fluid particles ;Dust particles Abstract : The Laminar flow of an unsteady liquid with uniform distribution of dust particles through a rectangular channel under the influence of exponential pressure gradient with respect to time has been investigated. The influence of the presence of the dust particles on fluid particles is discussed and graphs of velocity profile are drawn.
	Couttete Flow of a Dusty Incompressible Fluid with One of the Horizontal Moving Boundaries Suddenly Stopped Author : Ramacharyulu, N. Ch. Pattabhi ;Prasad, V.V. Ramana Source : Defence Science Journal ; Vol:31(3) ; 1981 ; pp 231-240 Subject : 532 Fluid Mechanics Keywords : Relaxation time ;Slip velocity;Skin friction;Flux;Impulsive motion;Dusty fluid Abstract : The unsteady flow of an incompressible viscous fluid with a uniform distribution of dust particles between two parallel plates when one of which is impulsively stopped from the state of uniform motion is studied. Analytical expressions for velocities of the fluid and dust particles have been obtained. It is found that the dust particles slip on the wall which is brought to rest impulsively instead of sticking to it; on the other hand, they stick to the stationary plate. The slip-velocity of the dust is noticed to be decreasing as the physical time increases and the relaxation time of the dust particles decrease.
	Start up Flow with Velocity slip in the Entrance Region of a Porous Circular Tube Start up Flow with Velocity slip in the Entrance Region of a Porous Circular Tube Author : Rajvanshi, S.C. ;Prakash, Om Source : Defence Science Journal ; Vol:30(1) ; 1980 ; pp 1-8 Subject : 532 Fluid Mechanics;532.542 Fluid Dynamics Keywords : Fluid injection ;Velocity profile;Viscous fluid Abstract : Suddenly started laminar flow of an incompressible viscous fluid in the entrance region of a porous circular tube is studied analytically, taking into account the tangential velocity slip at its surface. Adopting a similarity velocity profile of the form of nth.degree parabola in the boundary layer, the integrated forms of the equations of continuity, momentum and energy are solved by the method of characteristics. The entry length is seen reduced by the fluid injection across the wall of the tube and increased by the tangential velocity slip at it. Both these factors are found increasing the start-up time required for the full development of the flow.
	Fluid Rotating in the Presence of a Magnetic Field Author : Govindarajulu, T. Source : Defence Science Journal ; Vol:21(3) ; 1971 ; pp 171-174 Subject : 532 Fluid Mechanics;532.542 Fluid Dynamics Keywords : Rotating Fluid ;Thornley Abstract : The problem of rotating fluid recently considered by Thornley has been extended to electrically conducting fluids. It is found that the resonance effect encountered in the non magnetic case is eliminated by the presence of a magnetic field.
	Unsteady Flow of a Dusty Incompressible Fluid between Two Parallel Plates under an Impulsive Pressure Gradient Author : Ramacharyulu, Pattabhi ;Prasad, V.V. Ramana Source : Defence Science Journal ; Vol:30(3) ; 1980 ; pp 125-130 Subject : 532 Fluid Mechanics;532.542 Fluid Dynamics Keywords : Dust particles ;Viscous fluid Abstract : In the present investigation, an attempt is made to study the unsteady flow or an incompressible viscous fluid with uniform distribution of dust particles between two parallel plates under an impulsive pressure gradient. Analytical expressions for velocities of the fluid and the dust particles have been obtained. The variation of total fluxes for fluid and dust particles has been discussed. The influence on skin friction has been noticed.
	Two Dimensional Boundary Layer Growth with Suction Author : Lal, Krishna Source : Defence Science Journal ; Vol:20(3) ; 1970 ; pp 155-162 Subject : 532 Fluid Mechanics Keywords : Oscillatory motion ;Constant suction velocity;Fluid flow;Boundary layer equations Abstract : The boundary layer equations for the unsteady fluid flow with constant suction velocity have been worked out for the impulsive motion of a circular cylinder in the form V(t)=A exp (Ct) where A and C are certain constants. The stream function has been expanded in terms of some functions X/sub 0/(s) where s is a function of y coordinate. The phase angles for various terms have been calculated, and variations shown graphically for large and small frequency of oscillations, where the oscillatory motion is obtained on replacing C by iw.
	Slow Unsteady Flow of a Viscous Incompressible Fluid Between Two Wavy Walls Author : Gaur, Y.N. Source : Defence Science Journal ; Vol:21(1) ; 1971 ; pp 1-12 Subject : 532.542 Fluid Dynamics;532 Fluid Mechanics Keywords : Radiation Pressure Number ;Curved Shock Abstract : The jump conditions across a three dimensional curved shock in radiation gas dynamics have been derived. The successive approximations have been used for different cases depending upon the value of radiation pressure number. The results are obtained in a form very convenient to treat the further problems in the subject.
	Stability of Dusty Flow Between Two Rotating Coaxial Cylinders Author : Upadhyay, B.N. ;Pathak, R.S. Source : Defence Science Journal ; Vol:31(2) ; 1981 ; pp 155-165 Subject : 532 Fluid Mechanics Keywords : Principle of exchange of stabilities ;Rayleigh criterion;Relaxation time;Perturbations Abstract : The criterion for stability of dusty fluid flow between two coaxially rotating cylinders is derived by an examination of the stability of the basic flow to arbitrary perturbations. The perturbation equations are explored under the assumption that the relaxation time tarque (= m/k) of the dust particles is small. It is observed that the flow is always stable if Rayleigh's criterion meu>eta/sup 2/ is satisfied. The principle of exchange of stabilities is discussed and the characteristic value problem is solved under the narrow-gap approximations.
	Unsteady Flow Between Two Oscillating Plates Author : Khan, Abdul Aleem Source : Defence Science Journal ; Vol:19(2) ; 1969 ; pp 139-142 Subject : 532 Fluid Mechanics Keywords : Laplace transform technique ;Infinite plates Abstract : The flow of a viscous liquid between two harmonically oscillating infinite plates has been analysed when a body forces is applied at t=0, in the direction of motion of the plates. An expression for the velocity distribution has been obtained by the use of Laplace-transform technique.
	The Origin of Blue-Green Window and the Propagation of Radiation in Ocean Waters Author : Reghunath, A.T. ;Venkataramanan, V. ;Suviseshamuthu, D. Victor ;Krishnamohan, R. ;Prasad, B.Raghavendra ;Subramanian, C.K. ;Chandrasekhar, P. ;Narayanan, P.S. ;Ravisankar, M. ;Nampoori, V.P.N. ;Sathianandan, K. ;Raghuveer, S. Source : Defence Science Journal ; Vol:41(1) ; 1991 ; pp 1-20 Subject : 532 Fluid Mechanics Keywords : Attenuation spectrum ;Beam attenuation coefficient Abstract : A review of the present knowledge about the origin of blue-green window in the attenuation spectrum of ocean waters is presented. The various physical mechanisms which contribute to the formation of the window are dealt separately and discussed. The typical values of attenuation coefficient arising out of the various processes are compiled to obtain the total beam attenuation coefficient. These values are then compared with measured values of attenuation coefficient for ocean waters collected form Arabian sea and Bay of Bengal. The region of minimum attenuation in pure particle-free sea water is found to be at 450 to 500nm. It is shown that in the presence of suspended particles and chlorophy11,the window shifts to longer wavelength side. Some suggestions for future work in this area are also given in the concluding section.
	Arabian Sea Mini Warm Pool and its Influence on Acoustic Propagation Author : Hareesh Kumar, P. V.;Sanilkumar, K. V.;Prasada Rao, C. V. K. Source : Defence Science Journal ; Vol:57(1) ; 2007 ; pp 115-121 Subject : 53 Applied Physics;532 Fluid Mechanics Keywords : Arabian Sea mini warm pool;Acoustic propagation model;Transmission loss;Acoustic propagation Abstract : A systematic experiment was conducted in the eastern Arabian Sea for the first time exclusively to study the characteristics of the Arabian Sea mini warm pool1. The analysis revealed complex nature of the thermohaline and sonic layer distributions across the Arabian Sea mini warm pool. This mini warm pool was identified between 67.5 oE and 75 oE, where the sea surface temperature was in excess of 30.25 oC. At the core of this mini warm pool, warmer (>31.2 oC) and low saline (<34.6 PSU) waters were noticed. Further, very thin sonic layer (< 5 m) was noticed at the mini warm pool core, which increased eastward and westward. In this study, the acoustic propagation characteristics across and outside of the core, i.e., (i) within the mini warm pool core, (ii) eastern side of the mini warm pool core, and (iii) western side of the mini warm pool core, were assessed based on the output of a range-dependant acoustic model. In general, the occurrence of this mini warm pool was found to alter the propagation characteristics. Better propagation was obtained when the simulation was carried out on the eastern side of this mini warm pool, with source near the coast (i.e., downslope condition).
	Laminar Flow of an Electrically Conducting Incompressible Fluid Between Walls in the Presence of a Transverse Magnetic Field Author : Mathur, A.K. ;Verma, P.D. Source : Defence Science Journal ; Vol:19(1) ; 1969 ; pp 1-12 Subject : 532 Fluid Mechanics Keywords : Stream function ;Reyond's number;Magnetohydrodynamic laminar Abstract : Magnetohydrodynamic laminar flow of an electrically conducting, viscous, incompressible fluid between two wavy walls, whose equations are taken in the form of Fourier Series, has been investigated under the assumptions that epsional, the coefficient of roughness and R, the Reyond's number of the flow, are small. The stream function has been determined to the first order in epsional. For numerical investigation, the walls are considered to have the sinusoidal deformation. The velocity profiles for the longitudinal and the transverse velocities are drawn at various cross sections for M=0,1,2,epsional=0.5, R=0.1 and P/sub c,x/ R/sup 2/=0.1.
	Steady Radial Flow of Second Order Fluids between Two Infinite Parallel Discs One Rotating and the Other at Rest Author : Rajvanshi, S.C. Source : Defence Science Journal ; Vol:19(1) ; 1969 ; pp 39-48 Subject : 532 Fluid Mechanics Keywords : Reynolds number ;Radial flow;Fluids Abstract : The laminar radial flow of second order fluids between two infinite parallel discs (one rotating and the other at rest) has been discussed. A source of strength M is assumed to be present on the axis of rotation, which induces the radial flow. The solution is obtained in powers of the radius vector, for small values of the Reynolds number R (=pwd/sup 2/fi/sub 1/).
	Shear Flow of an Elastico-Viscous Fluid Past a Porous Flat Plate Author : Mishra, Shankar Prasad Source : Defence Science Journal ; Vol:15(2) ; 1965 ; pp 61-64 Subject : 532 Fluid Mechanics Keywords : Retardation Time;Skin-Fraction;Fluid Injection Abstract : Considering shear flow of an elastico-viscous fluid past a porous flat plate, it has been found that a steady solution for the velocity field is not possible if there is fluid injection at the plate and that the velocity in the shear flow increases the skin-fraction at the plate. if the wall is impermeable, the elastic elements do not affect the velocity field. The thickness of the boundary layer on the plate decreases with the increases of relaxation time, but it increases with the increase of retardation time.
	Couette Flow of a Viscous Electrically Conducting Fluid in a Porous Annulus Author : Jain, P.C. ;Gupta, S.C. Source : Defence Science Journal ; Vol:31(1) ; 1981 ; pp 53-61 Subject : 532.542 Fluid Dynamics;532 Fluid Mechanics Keywords : Viscous incompressible fluid ;Porous coaxial cylinders;Transverse magnetic field Abstract : In the present paper the author has studied the Couette flow of a viscous incompressible fluid under a transverse magnetic field in an annular space bounded by two porous coaxial cylinders which are moving with arbitrary time dependent velocities parallel to the axis.
	Converging Cylindrical Shock Waves in a Nonideal Gas With an Axial Magnetic Field Author : Vishwakarma, J. P. ;Pandey, Sateesh N. Source : Defence Science Journal ; Vol:56(5) ; 2006 ; pp 721-732 Subject : 53 Applied Physics;532 Fluid Mechanics Keywords : Converging shock waves;Axial magnetic field;CCW method;Nonideal gas Abstract : This paper analyses the propagation of converging cylindrical shock waves in a nonideal gas, in the presence of an axial magnetic field. Chester-Chisnell-Whitham’s method has been employed to determine the shock velocity and the other flow-variables just behind the shock in the cases, when (i) the gas is weakly ionised before and behind the shock front, (ii) the gas is strongly ionised before and behind the shock front, and (iii) nonionised gas undergoes intense ionisation as a result of the passage of the shock. The effects of the nonidealness of the gas, the conductivity of the gas, and the axial magnetic field have been investigated. It is found that in the case (i), an increase in the value of parameter (d) characterising the nonidealness of the gas accelerates the convergence of the shock. In the case (ii), the shock speed and pressure behind the shock increase very fast as the axis is approached; and this increase occurs earlier if the strength of the initial magnetic field is increased. In the case (iii), for smaller values of the initial magnetic field, the shock speed, and pressure behind the shock decrease very fast after attaining a maximum; and for higher values of the initial magnetic field, the tendency of decrease appears from the beginning. This shows that the magnetic field has damping effect on the shock propagation. In the case (iii), it was also found that the growth of the shock in the initial phase and decay in the last phase were faster when it was converging in a nonideal gas in comparison with that in a perfect gas. Further, it has been shown that the gas-ionising nature of the shock has damping effect on its convergence.
	Reliability, Availability, and Maintainability of Intermittently-used Repairable Systems Author : Rajpal, P. S.;Shishodia, K. S.;Sekhon, G. S. Source : Defence Science Journal ; Vol:57(2) ; 2007 ; pp 211-222 Subject : 532 Fluid Mechanics;53 Applied Physics Keywords : Repairable system;Reliability;Weibull distribution;CMRAM;Transport helicopter;Simulation model;System reliability;System maintainability;Monte-Carlo simulation Abstract : A composite measure comprising linear combination of reliability, availability, and maintainability (CMRAM) is proposed for an intermittently-used complex repairable system, namely a transport helicopter. The failure data are fitted in Weibull distribution for overlapping intervals of operating time to capture the effect of recent maintenance and other actions. Evaluation of CMRAM is helpful in formulating future operational and maintenance strategies.
	Estimation of Rheological Properties of Snow Subjected to Creep Author : Chandel, Chaman;Srivastava, P. K. ;Upadhyay, Agraj Source : Defence Science Journal ; Vol:57(4) ; 2007 ; pp 393-401 Subject : 53 Applied Physics;532 Fluid Mechanics Keywords : Snow;Snowpack;Creep;Rheological model creep behaviour;Visco-elastic model;Rheological properties;Snow mechanics;Creep deformation behaviour;Maxwell model;Burger’s model Abstract : Creep is one of the most important phenomenons to determine the settlement of snow. Snow, in natural conditions, exists at temperature quite close to its melting point and deforms very fast. The settlement of snow is the result of creep phenomenon under the action of overburden pressure as well as due to metamorphic processes going on within the snowpack. In this communication, creep behaviour of snow is simulated with four-parameter viscoelastic fluid model. This viscoelastic character is basically controlled or monitored by various rheological constants. Estimation of all the rheological constants in the four-parameter viscoelastic fluid model appropriate for the creep properties of snow is done. Total 91 uniaxial unconfined constant stress experiments on sieved snow were conducted at controlled temperature conditions. The effect of density and varying temperature on these constants is found to be remarkable.