Numerical analysis of flows past two parallel flat plates in the free-molecular regime

2020 ◽  
Vol 34 (14n16) ◽  
pp. 2040120
Author(s):  
Xu-Hong Jin ◽  
Fei Huang ◽  
Xiao-Li Cheng ◽  
Qiang Wang ◽  
Bing Wang
Keyword(s):  
Monte Carlo ◽  
Numerical Analysis ◽  
Radius Ratio ◽  
Molecular Flow ◽  
Free Molecular Flow ◽  
Considerable Influence ◽  
Multiple Reflections ◽  
Flat Plates ◽  
Aerodynamic Forces ◽  
Pressure Distributions

A numerical investigation is presented for a free-molecular flow past two parallel circular flat plates using the test particle Monte Carlo (TPMC) method, with flow shadowing and multiple reflections analyzed. Flow shadowing and multiple reflections have a significant effect on aerodynamic forces, and the distance-to-radius ratio of the two plates has a considerable influence on flow shadowing and multiple reflections. As the distance-to-radius ratio increases, flow shadowing and multiple reflections become weaker. Different distance-to-radius ratios result in different surface pressure distributions.

Numerical simulation for flow shadowing and multiple reflections between two flat plates in the free-molecular regime

2018 ◽  
Vol 32 (12n13) ◽  
pp. 1840042 ◽  
Author(s):  
Xuhong Jin ◽  
Fei Huang ◽  
Xiaoli Cheng ◽  
Qiang Wang
Keyword(s):  
Pitch Angle ◽  
Dominant Role ◽  
Area Ratio ◽  
Molecular Flow ◽  
Back Side ◽  
Front Side ◽  
Aerodynamic Coefficients ◽  
Multiple Reflections ◽  
Flat Plates ◽  
Pressure Distributions

A free-molecular flow past two parallel circular flat plates is analyzed by the test particle Monte Carlo (TPMC) method. Flow shadowing and multiple reflections have a vital influence on aerodynamic coefficients of the two plates. At the pitch angle of 0[Formula: see text], lift coefficients of each plate do not equal to zero. Flow shadowing has a significant effect on the front side of the shaded plate while multiple reflections play a dominant role on the back side of the shading one. The area ratio of the two plates has an evident effect on flow shadowing and multiple reflections, and different area ratios lead to different pressure distributions on the front side of the shaded plate and the back side of the shading one.

Monte Carlo simulation of gas free molecular flow in turbo molecular pump’s inlet tube

2018 ◽  
Vol 44 (15) ◽  
pp. 1261-1269 ◽  
Author(s):  
Kun Sun ◽  
Shiwei Zhang ◽  
Yajie Li ◽  
Zhijun Zhang ◽  
Haitao Li ◽  
...  
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Molecular Flow ◽  
Free Molecular Flow ◽  
Inlet Tube

Coupling of Heat and Momentum Transfer Between Nanostructured Surfaces

2009 ◽  
Author(s):  
Alexander A. Donkov ◽  
Steffen Hardt ◽  
Sudarshan Tiwari ◽  
Axel Klar
Keyword(s):  
Heat Transfer ◽  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Numerical Solutions ◽  
Small Scale ◽  
Molecular Flow ◽  
Transition Regime ◽  
Free Molecular Flow ◽  
Direction Parallel ◽  
Nanostructured Surfaces

Heat transfer between nanostructured surfaces separated by a thin gas film is studied in the free-molecular flow and in the transition regime. Besides topographic features the surfaces are characterized by regions with different boundary conditions displaying either diffuse or specular reflection of the molecules. The thermal conductivity of the materials on both sides of the gas film is assumed to be very high such that isothermal conditions may be applied at both surfaces. We analyze the problem using a combination of analytical techniques in the free-molecular flow regime and Monte-Carlo simulations. Under certain conditions, when the surfaces are held at different temperatures heat transfer is accompanied by a transfer of momentum such that a force is created parallel to the surfaces. This force can be significant and vanishes in the classical regime when the continuum transport equations can be applied. It is only observed if the reflection symmetry in a direction parallel to the surfaces is broken. We derive an analytical expression for the thermally-induced force as a function of the geometric parameters characterizing the surface topography and compare the results to Monte-Carlo simulations. The latter provide numerical solutions of the Boltzmann equation both in the free-molecular flow and in the transition regime. The scenario studied points to a novel method for conversion of thermal into kinetic energy and may find applications in small-scale energy converters.

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