Numerical simulation of rarefied flow through a slit. Part I: Direct simulation Monte Carlo results

1993 ◽  
Vol 5 (1) ◽  
pp. 235-242 ◽  
Author(s):  
D. C. Wadsworth ◽  
D. A. Erwin
Keyword(s):  
Numerical Simulation ◽  
Monte Carlo ◽  
Direct Simulation Monte Carlo ◽  
Direct Simulation ◽  
Rarefied Flow ◽  
Flow Through ◽  
Simulation Monte Carlo

Modelling of chemical reactions in hypersonic rarefied flow with the direct simulation Monte Carlo method

1996 ◽  
Vol 312 ◽  
pp. 149-172 ◽  
Author(s):  
Michael A. Gallis ◽  
John K. Harvey
Keyword(s):  
Monte Carlo ◽  
Chemical Reactions ◽  
Energy Exchange ◽  
Chemical Reactivity ◽  
Direct Simulation Monte Carlo ◽  
Direct Simulation ◽  
Rarefied Flow ◽  
Rarefied Flows ◽  
Exchange Processes ◽  
Simulation Monte Carlo

In this paper the phenomenon of chemical reactivity in hypersonic rarefied flows is examined. A new model is developed to describe the reactions and post-collision energy exchange processes that take place under conditions of molecular non-equilibrium. The new scheme, which is applied within the framework of the direct simulation Monte Carlo (DSMC) method, draws its inspiration from the principles of maximum entropy which were developed by Levine & Bernstein. Sample hypersonic flow fields, typical of spacecraft re-entry conditions in which reactions play an important role, are presented and compared with results from experiments and other DSMC calculations. The latter use traditional methods for the modelling of chemical reactions and energy exchange. The differences are discussed and evaluated.

Gas Properties Effects in Microchannel Studies Using Direct Simulation Monte Carlo

2010 ◽  
Author(s):  
Masoud Darbandi ◽  
Abolfazl Karchani ◽  
Hassan Akhlaghi ◽  
Gerry Schneider
Keyword(s):  
Heat Transfer ◽  
Monte Carlo ◽  
Slip Flow ◽  
Direct Simulation Monte Carlo ◽  
Direct Simulation ◽  
Polyatomic Gases ◽  
Flow And Heat Transfer ◽  
Flow Through ◽  
Simulation Monte Carlo ◽  
Gas Properties

This paper concern is to study the gas properties effect in flow and heat transfer behaviors through microchannels using the direct simulation Monte Carlo method. The flow is rarefied and supersonic. The channels are investigated at two different inlet boundary conditions. The collision process is modeled using the NTC (no-time-counter) scheme. The VHS model is chosen to simulate collision between particle pairs. The study is provided for many different gases including nitrogen, helium, and oxygen. The Knudsen number is chosen in a manner to provide slip flow through the channel. The results show that the heat transfer from the wall is lower for heavier gases. A comparative study among the monatomic, diatomic, polyatomic gases shows that the heat transfer rate is lower for the polyatomic gases. The result shows that, the heat transfer from the wall is lower for the heavier gases than that for the lighter gas. For a fixed Mach number, the heat transfer from the wall decreases as the molecular diameter increases.

Development of Object-Oriented Direct Simulation Monte Carlo Code for Modeling of Rarefied Flow around Geometries of Arbitrary Shapes

2011 ◽  
Vol 110-116 ◽  
pp. 2491-2496
Author(s):  
Sourabh Jain ◽  
Prabhu Ramachandran
Keyword(s):  
Monte Carlo ◽  
Heat Conduction Problem ◽  
Direct Simulation Monte Carlo ◽  
Object Oriented ◽  
Navier Stokes ◽  
Monte Carlo Code ◽  
Direct Simulation ◽  
Rarefied Flow ◽  
Simulation Monte Carlo ◽  
Arbitrary Shapes

Rarefied flows cannot be accurately simulated using Navier-Stokes (N-S) equations. The Direct Simulation Monte-Carlo (DSMC) technique is a particle based method for accurate simulation of flows under such conditions. A DSMC code is developed using an object-oriented (OO) approach which can simulate flows around arbitrary shapes. Hence, the flux from such boundaries can be correctly predicted. The object-oriented approach enables for easy modification of the code. For example, it is easy to use different collision models to implement different relaxation algorithm. The code is validated for the one-dimensional Fourier heat conduction problem. Results for the development of a shock due to supersonic flow over a 15 degree wedge are also presented. Inclined boundary of the wedge is correctly captured as the particles interact with the the exact shape of the boundary. Shock angle is found more than expected due to rarefaction effects.

Various Boundary Condition Implementation to Study Microfilters Using DSMC Simulation

2010 ◽  
Author(s):  
Masoud Darbandi ◽  
Hassan Akhlaghi ◽  
Abolfazl Karchani ◽  
Soheyl Vakili
Keyword(s):  
Boundary Condition ◽  
Monte Carlo ◽  
Gas Flow ◽  
Direct Simulation Monte Carlo ◽  
Direct Simulation ◽  
Dsmc Method ◽  
Uniform Distributions ◽  
Dsmc Simulation ◽  
Flow Through ◽  
Simulation Monte Carlo

In this study, we present a vast boundary condition treatment to simulate gas flow through microfilters using direct simulation Monte Carlo (DSMC) method. We examine the effects of different boundary condition treatments on the density, pressure, and velocity distributions and suggest the best conditions to simulate gas flow through microfilters. We also refine the effects of upstream and downstream locations on the solution. The results show that uniform distributions can be achieved if we apply the inlet/outlet boundary condition at appropriate upstream and downstream distances. We also show that all the suggested boundary conditions suitably predict the pressure drop coefficient factor across the filter. To evaluate the current results they are compared with some available empirical formulations.

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