Studies on Gas Flow through Smooth Microchannel Surface – Fabrication, Characterization, Analysis, and Tangential Momentum Accommodation Coefficient Comparison

Abstract

In the present work, experimental and numerical findings of tangential momentum accommodation coefficient (TMAC) on smooth microchannel surface and comparison with rough surface was performed. A modified silicon micromachining technique was used to achieve smooth surface of the microchannel. About two orders of magnitude decrease in surface roughness was obtained when compared to previous studies. Second order slip model was derived, and a special procedure was developed to simulate the gas flow in microchannel from slip-to-transition regimes. The microchannel system with 20 parallel channels were fabricated on a surface modified silicon surface and flow characteristics were studied by generating accurate and high resolution experimental data with comparison of simulation results. TMAC values were found up to an outlet Knudsen number of 0.851 with nitrogen and the second order slip coefficients were found. When compared to previous TMAC values for rough surfaces, low values were obtained in the present case. This decrease is an indication of the increase in slip velocity due to the reduction of surface roughness.

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Notes on contributors

Kandaswamy Srinivasan

Kandaswamy Srinivasan is an Associate Professor in the Research and Development Centre at BMS College of Engineering, Bangalore, India. Earlier he was working as a lead scientist in a point-of-care medical diagnostics industry for more than 8 years and has extensive experience in microfluidic chip design, prototyping and manufacture. He received his Master’s degree in Thermal Engineering from University of Madras and Ph.D. degree in Microflows from Indian Institute of Technology Delhi, India in 2011. His research interests include modeling and experimental analysis of gas microflows and microfluidics microelectro mechanical systems device modeling.

Paruchuri M.V. Subbarao

Paruchuri M.V. Subbarao is a Professor of Thermal and Fluid Sciences at Indian Institute of Technology Delhi, India. He received his Ph.D. degree in 1994 from IIT Kanpur. His research interests include computational and experimental microfluidics study, computational analysis of high speed gas dynamics, computational analysis of turbulence enhancement, tomographic reconstruction of fluid mechanics and heat transfer. He is the author or coauthor of 4 books and more than 100 articles. He developed and currently leads the microfluid mechanics group in Mechanical Engineering Department at IIT Delhi. He is currently Ray W. Herrick chair professor in the Mechanical Engineering Department.

Sunil R. Kale

Sunil R. Kale is a Professor in Mechanical Engineering Department at Indian Institute of Technology Delhi, India. He received his Ph.D. degree from Stanford University. His research interests include heat transfer, micro-fluid mechanics, particle-laden flows, combustion and energy conversion. He has been working in this field for more than 25 years and performed various industrial and academic projects and served as Head of Mechanical Engineering Department for four years.