Comparison of Various Pressure Based Boundary Conditions for Three-Dimensional Subsonic DSMC Simulation

Abstract

Three-dimensional (3D) direct simulation Monte Carlo (DSMC) has been used to simulate flow in a straight microchannel using an in-house parallelized code. In the present work, a comparative study of seven boundary conditions is carried out with respect to time required for achieving steady-state, accuracy in predicting the specified pressure at the boundaries, and the total simulation time required for attaining a statistical error within one percent. The effect of changing the Knudsen number, pressure ratio (PR), and cross aspect ratio (CAR) on these parameters is also studied. The presence of a boundary is seen to affect the simulated pressure in a cell when compared to the specified pressure, the difference being highest for corner cells and least for cells away from walls. All boundary conditions tested work well at the inlet boundary; however, similar results are not obtained at the outlet boundary. For the same cell size, the schemes that employ first- and second-order corrections lead to a smaller pressure difference compared to schemes applying no corrections. The best predictions can be obtained by using first-order corrections with finer cell size close to the boundary. For most of the simulated cases, the boundary condition employing the characteristic scheme with nonequilibrium effect leads to the minimum simulation time. Considering the nonequilibrium effect, prediction of inlet and outlet pressures and the speed of simulation, the characteristic scheme with nonequilibrium effect performs better than all the other schemes, at least over the range of parameters investigated herein.

Derivation of extended-OBurnett and super-OBurnett equations and their analytical solution to plane Poiseuille flow at non-zero Knudsen number

“…Additionally, a novel collision scheme, known as the simplified Bernoulli trial, has been introduced in Stefanov (2011). The DSMC technique has also been employed in Gavasane et al (2011Gavasane et al ( , 2017, Jadhav et al (2017), Shah, Agrawal & Bhandarkar (2018a, Shah et al (2018b) andJadhav, Gavasane & for different microchannel flow and shock wave problems. That is why we also resort to DSMC data to validate the analytical solution obtained above.…”

“…(2017), Shah, Agrawal & Bhandarkar (2018 a ), Shah et al. (2018 b ) and Jadhav, Gavasane & Agrawal (2021) for different microchannel flow and shock wave problems. That is why we also resort to DSMC data to validate the analytical solution obtained above.…”

Fluid flow and heat transfer in microchannel heat sinks: Modelling review and recent progress

“…Their results showed that the pressure distribution was related to the flow direction and the normal position of the wall, and obtained the distribution expression of gas flow pressure in the microchannel. Shah et al [91] used the DSMC method to simulate the nitrogen flow in the straight microchannel under seven different boundary conditions. Their results presented that the pressure, velocity and translation temperature of microchannels under different boundary conditions would have the same variation trend.…”

Low-Speed DSMC Simulations of Hotwire Anemometers at High-Altitude Conditions

“…where n f is the gas number density at [12,22,23,30,35,36]. A value of N ppc = 10 was used for results presented in the current study.…”