With the aid of direct simulation Monte Carlo (DSMC), a detailed investigation is reported considering the fluid and thermal characteristics of rarefied gas flow with regard to various arrangements for radiometric pumps featuring vane and ratchet structures. For the same, we consider three geometries of radiometric pumps consisting of channels with their bottom or top surfaces periodically patterned with different structures. The structures in the design of the first geometry are assumed to be on the bottom wall and consist of a simple vane. The second and third geometries contain either a channel with double isosceles triangular fins on its lowermost surface or a zigzag channel with double isosceles triangular fins on both walls. The temperature is kept steady on the horizontal walls of the channel; thus, radiometric flow is produced by subjecting the adjacent sides of the vane/ratchet to constant but unequal temperatures. The DSMC simulations are performed at a Knudsen number based on the vane/ratchet height of around one. The dominant mechanism in the production of radiometric force is clarified for the examined configurations. Our results demonstrate that at the investigated Knudsen number the zigzag channel experiences maximum induced velocity with a parabolic velocity profile, whereas its net radiometric force vanishes. In the case of all other configurations, the flow pattern resembles a Couette flow in the open section of the channel situated above the vane/ratchet. For binary mixtures, we demonstrate that the arrangement with the double isosceles teeth embedded just on the bottom wall performs a measurable gas separation with a linear species variation along the pump height.

Biographical Sketch:

    Ehsan Roohi is an Associate Prof. at the School of Aerospace Engineering, International Center for Applied Mechanics, Xi’an Jiaotong University, Xi'an, China. Dr. Roohi took his Ph.D. (Cum laude) in Aerospace Eng. from Sharif University of Technology, Tehran, Iran, in 2010. Part of his Ph.D. thesis was performed at the University of Strathclyde, UK, under the supervision of late Prof. Jason Reese. During the last decade, Dr. Roohi has been known internationally. He has been elected as the Distinguished Young Researcher in Mechanical Engineering in the country by Iranian Academy of Science (IAS) in 2019, which is the highest academic award for young (under 40) researchers given to just one researcher in the selected fields per year. At the international level, Dr. Roohi is among the top 1% journal reviewers in the field of Engineering since 2016 for three successive years, according to Publon report. This success reflects significant contributions that Dr. Roohi made in the rarefied gas dynamics field (RGD) and cavitating flow to the aerospace and mechanical engineering communities, mainly.

    Dr. Roohi research could be categorized in the following three subjects: 1) rarefied gas dynamics; 2) cavitating flows, and 3) large eddy simulations (LES). Overall, the work published by Dr. Roohi in international, peer-review top journal papers received around 1400 citations (Scopus), gaining an h-index of 22 in Scopus. He has a robust developing record with relevant research publications in top-tier journals, i.e., by publishing more than 80 journal papers in high-rank international journals in engineering physics, fluid dynamics, and heat transfer, i.e., Physics Reports (IF=28), JFM, Applied Mathematical Modelling, Physics of Fluids, Physical Review E, JCP, International Journal of Heat and Mass Transfer, International Journal of Thermal Science, Computers & Fluids, and Scientific Reports.