Parametric Analysis of Energy Absorption in Micro-particle Photophoresis in Absorbing Gaseous Media

W.K. Li; C.Y. Soong; C.H. Liu; P.Y. Tzeng

doi:10.14429/dsj.60.347

W.K. Li National Defense University, Tahsi
C.Y. Soong Feng Chia University, Seatwen
C.H. Liu Yuanpei University, Hsinchu
P.Y. Tzeng National Defense University, Tahsi

DOI: https://doi.org/10.14429/dsj.60.347

Keywords: Heat source function, size parameter, absorptivity, refractivity, particle photophoresis

Abstract

The study deals with photophoresis of a spherical micro-particle suspended in absorbing gaseous media. Photophoretic motion of the particle stems from the asymmetric distribution of absorbed energy within the particle. By evaluating the so-called heat source function at various conditions, the study focuses on the effects of governing parameters on the energy distribution within the particle and their potential influences to the photophoresis. The results reveal that the increase in either particle size or absorptivity enhances the energy intensity on the illuminated (leading) side and tends to generate positive photophoresis. For a particle of low absorptivity, the energy distribution is dominated by particle refraction. Enhancing particle refractivity, the energy tends to be focused onto a certain spot area on the shaded (trailing) side and leads to a tendency of negative photophoresis. Increasing medium absorptivity significantly degrades the level of energy absorbed by the particle and in turn weakens the driving force of the particle photophoresis.

Defence Science Journal, 2010, 60(3), pp.233-237, DOI:http://dx.doi.org/10.14429/dsj.60.347

Author Biographies

W.K. Li, National Defense University, Tahsi

PhD student at Chung-Cheng Institute of Technology, National Defense University. He has worked on light scattering, optofluidics, multi-physics interfacial phenomena, etc.

C.Y. Soong, Feng Chia University, Seatwen

FCU Distinguished Professor affiliated to the Department of Aerospace and Systems Engineering. His research areas include: Transport and interfacial phenomena in micro/nanofluidics, optofluidics, transport phenomena in energy systems, nonlinear dynamics and chaos control, unmanned micro/mini air vehicles, bio-flapping flight, thermofluids in rotating systems, etc.

C.H. Liu, Yuanpei University, Hsinchu

Dean of the College of Biomedical Science and Technology. His research areas include: haemodynamic simulation of aneurysm coiling, transport phenomena in microfluidics, optofluidics, numerical simulation of annual reverse-flow gas turbine combustor, transport phenomena in wind energy systems, and vortex method and its applications.

P.Y. Tzeng, National Defense University, Tahsi

Professor affiliated to the Department of Mechatronic, Energy and Aerospace Engineering, National Defense University, Taiwan, ROC. His research areas include: DSMC modelling of rarefied gas flow and heat transfer in micro/nano systems, optofluidics, computational gas dynamics in propulsion systems, turbulence modelling, etc.