A Study of Wall Temperature Jump Using UGKS Simulation With Diffuse-Specular Maxwell-Type Boundary

2021 ◽  
Author(s):  
Lianfu Dai ◽  
Huiying Wu
Keyword(s):  
Knudsen Number ◽  
Wall Temperature ◽  
Gas Flow ◽  
Temperature Jump ◽  
Rarefied Gas ◽  
Flow Simulation ◽  
Unsteady State ◽  
Relative Temperature ◽  
Boundary Treatment ◽  
Type Boundary

Abstract As the Maxwell-type boundary treatment can automatically capture temperature jump on boundary, it is widely used in gas flow simulation like Lattice Boltzmann method and Direct simulation Monte Carlo method. In present study, diffuse-specular Maxwell-type boundary with a diffusive fraction (a), which decides the mechanism of interaction between gas molecules and boundary, is realized in UGKS simulation. This diffuse-specular boundary can recover diffuse Maxwell boundary when a = 1.0, which proves the reliability of present boundary treatment. The influence of diffusive fraction on wall temperature jump under Knudsen number ranging from 0.001 to 1.0 is tested. The test cases are steady and unsteady state conditions of heat conduction and Couette flow between two infinite plates setting at specified temperatures. It is found that: 1) for cases of Knudsen number ranging from 0.01 to 1.0, owing to the loss of influence from equilibrium part on evolution of boundary gas distribution, the relative temperature jump increases when diffusive fraction varies from 1.0 to 0.25, this phenomenon is especially obvious on extreme point part in unsteady state cases; 2) for cases of Knudsen number equaling to 0.001, diffusive fraction has no significance influence on temperature jump as the temperature jump is less noticeable for such condition. Present study will help the further researches of heat transfer in rarefied gas.

On the Rarefied Gas Flow in Pipes

2005 ◽  
Author(s):  
Vladan D. Djordjevic
Keyword(s):  
Knudsen Number ◽  
Gas Flow ◽  
Rarefied Gas ◽  
Natural Extension ◽  
Slip Boundary Condition ◽  
Molecular Flow ◽  
Rarefied Gas Flow ◽  
Number Range ◽  
Average Value ◽  
Linearized Boltzmann Equation

Rarefied gas flow in a pipe is treated in the paper by modeling the slip boundary condition by means of a fractional derivative. At that the order of the derivative is conveniently chosen to be a function of the average value of the Knudsen number so that the entire Knudsen number range, from continuum flow to free molecular flow, is covered. Very good agreement with the solutions of linearized Boltzmann equation is achieved. The paper represents a natural extension of the work of the same author on the rarefied micro channel flow, published earlier.

Experimental study of heat transfer in rarefied gas flow in a circular tube with constant wall temperature

2018 ◽  
Vol 93 ◽  
pp. 326-333 ◽  
Author(s):  
Vadiraj Hemadri ◽  
G.S. Biradar ◽  
Nishant Shah ◽  
Richie Garg ◽  
U.V. Bhandarkar ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Wall Temperature ◽  
Gas Flow ◽  
Rarefied Gas ◽  
Circular Tube ◽  
Rarefied Gas Flow ◽  
Constant Wall Temperature

DSMC simulation of rarefied gas flow over a 2D backward-facing step in the transitional flow regime: Effect of Mach number and wall temperature

2020 ◽  
pp. 095441002095987
Author(s):  
Deepak Nabapure ◽  
Ram Chandra Murthy K
Keyword(s):  
Mach Number ◽  
Flow Regime ◽  
Surface Properties ◽  
Wall Temperature ◽  
Gas Flow ◽  
Rarefied Gas ◽  
Transitional Flow ◽  
Flow Properties ◽  
Rarefied Gas Flow ◽  
Backward Facing Step

Rarefied gas flow over a backward-facing step (BFS) is often encountered in separating flows prevalent in aerodynamic flows, engine flows, condensers, space vehicles, heat transfer systems, and microflows. Direct Simulation Monte Carlo (DSMC) is a powerful tool to investigate such flows. The purpose of this research is to assess the impact of Mach number and wall temperature on the flow and surface properties in the transitional flow regime. The Mach numbers considered are 5, 10, 25, 30, and the ratio of the temperature of the wall to that of freestream considered are 1, 2, 4, 8. The Reynolds number for the cases studied is 8.6, 17.2, 43, and 51.7, respectively. Typically the flow properties near the wall are found to increase with both Mach number and wall temperature owing to compressibility and viscous dissipation effects. The variation in flow properties is more sensitive to Mach number than the wall temperature. The surface properties are found to decrease with Mach number and increase with wall temperature. Moreover, in the wake of the step, the vortex’s recirculation length is reasonably independent of both free stream Mach number and wall temperature, whereas it decreases with Knudsen number.

Rarefied Gas Flow Through a Circular Orifice and Short Tubes

1984 ◽  
Vol 106 (4) ◽  
pp. 367-373 ◽  
Author(s):  
Tetsuo Fujimoto ◽  
Masaru Usami
Keyword(s):  
Knudsen Number ◽  
Gas Flow ◽  
Rarefied Gas ◽  
Pressure Ratio ◽  
Diameter Ratio ◽  
Empirical Equations ◽  
Rarefied Gas Flow ◽  
High Pressure Ratio ◽  
Circular Orifice ◽  
Flow Through

Rarefied gas flow through a circular orifice and short tubes has been investigated experimentally, and the conductance of the aperture has been calculated for Knudsen number between 2 × 10−4 and 50. The unsteady approach was adopted, in which the decay of pressure in an upstream chamber was measured as a function of time. For flow with high pressure ratio, empirical equations of the conductance are proposed as a function of Reynolds number, or Knudsen number, and length-to-diameter ratio of the apertures.

scholarly journals Erratum: “A rarefied gas flow caused by a discontinuous wall temperature” [Phys. Fluids 13, 2645 (2001)]

2001 ◽  
Vol 13 (12) ◽  
pp. 3843-3843 ◽  
Author(s):  
Kazuo Aoki ◽  
Shigeru Takata ◽  
Hidefumi Aikawa ◽  
François Golse
Keyword(s):  
Wall Temperature ◽  
Gas Flow ◽  
Rarefied Gas ◽  
Rarefied Gas Flow

scholarly journals Rarefied gas flow around a sharp edge induced by a temperature field

2012 ◽  
Vol 694 ◽  
pp. 191-224 ◽  
Author(s):  
Satoshi Taguchi ◽  
Kazuo Aoki
Keyword(s):  
Knudsen Number ◽  
Gas Flow ◽  
Rarefied Gas ◽  
Structural Similarity ◽  
Rarefied Gas Flow ◽  
Bgk Model ◽  
Thermally Induced ◽  
Wide Range ◽  
Flow Features ◽  
Limiting Behaviour

AbstractA rarefied gas flow thermally induced around a heated (or cooled) flat plate, contained in a vessel, is considered in two different situations: (i) both sides of the plate are simultaneously and uniformly heated (or cooled); and (ii) only one side of the plate is uniformly heated. The former is known as the thermal edge flow and the latter, typically observed in the Crookes radiometer, may be called the radiometric flow. The steady behaviour of the gas induced in the container is investigated on the basis of the Bhatnagar–Gross–Krook (BGK) model of the Boltzmann equation and the diffuse reflection boundary condition by means of an accurate finite-difference method. The flow features are clarified for a wide range of the Knudsen number, with a particular emphasis placed on the structural similarity between the two flows. The limiting behaviour of the flow as the Knudsen number tends to zero (and thus the system approaches the continuum limit) is investigated for both flows. The detailed structure of the normal stress on the plate as well as the cause of the radiometric force (the force acting on the plate from the hotter to the colder side) is also clarified for the present infinitely thin plate.

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