Development of Particle Methods for Computing MEMS Gas Flows

2000 ◽  
Author(s):  
Quanhua Sun ◽  
Iain D. Boyd ◽  
Jing Fan
Keyword(s):  
Rarefied Gas ◽  
Particle Methods ◽  
Large Temperature ◽  
Gas Flows ◽  
Micro Electro Mechanical Systems ◽  
Design And Optimization ◽  
Information Preservation ◽  
Preservation Method ◽  
Domain Boundaries ◽  
Low Levels

Abstract The development of particle methods to simulate flows related to micro-electro-mechanical systems is described. This effort is aimed at increasing our understanding of rarefied gas behavior to facilitate the design and optimization of micro-devices. The proposed information preservation method preserves macroscopic information of the flow as the particles move and interact with each other and the domain boundaries. The results exhibit very low levels of statistical scatter, which helps apply the method to low speed MEMS flows. In the implementation, specific consideration is needed for flows with large temperature variation.

scholarly journals Development of an Efficient Particle Approach for Micro-Scale Gas Flow Simulations

2009 ◽  
Author(s):  
Quanhua Sun ◽  
Feng Li ◽  
Jing Fan ◽  
Chunpei Cai
Keyword(s):  
Cell Size ◽  
Gas Flow ◽  
Rarefied Gas ◽  
Direct Simulation Monte Carlo ◽  
Gas Flows ◽  
Dsmc Method ◽  
Low Speed ◽  
Micro Scale ◽  
Information Preservation ◽  
Cfd Method

The micro-scale gas flows are usually low-speed flows and exhibit rarefied gas effects. It is challenging to simulate these flows because traditional CFD method is unable to capture the rarefied gas effects and the direct simulation Monte Carlo (DSMC) method is very inefficient for low-speed flows. In this study we combine two techniques to improve the efficiency of the DSMC method. The information preservation technique is used to reduce the statistical noise and the cell-size relaxed technique is employed to increase the effective cell size. The new cell-size relaxed IP method is found capable of simulating micro-scale gas flows as shown by the 2D lid-driven cavity flows.

A High Order Theory for an Isothermal Rarefied Gas Flow in Micro Channels

2003 ◽  
Author(s):  
Nevena D. Stevanovic
Keyword(s):  
Small Parameter ◽  
Gas Flow ◽  
Rarefied Gas ◽  
Reynolds Numbers ◽  
Order Theory ◽  
Gas Flows ◽  
Regular Perturbation ◽  
Micro Electro Mechanical Systems ◽  
Slip Boundary ◽  
Micro Channels

Gas flows take place in a number of micro-electro-mechanical systems (MEMS). Since the dimensions of the MEMS are within μm range, it is necessary to take into account the gas rarefaction effects in investigations of these flows. This paper presents the solution and analysis of isothermal compressible gas flow through micro channels with slow varying cross section under low Mach number conditions. The problem is solved by the introduction of the small parameter ε that presents the square of the Mach and Reynolds numbers ratio. Small parameter ε is used in a regular perturbation analysis of the problem. The exact dependence among Mach, Reynolds and Knudsen number is utilized, which leads to accurate prediction of the influence of the inertia forces and the slip boundary conditions.

scholarly journals Examination of the LBM in Simulation of Microchannel Flow in Transitional Regime

2003 ◽  
Author(s):  
Ching Shen ◽  
Dong-Bo Tian ◽  
Chong Xie ◽  
Jing Fan
Keyword(s):  
Direct Simulation Monte Carlo ◽  
Channel Flows ◽  
Transitional Flow ◽  
Gas Flows ◽  
Micro Channel ◽  
Transitional Regime ◽  
Micro Electro Mechanical Systems ◽  
Information Preservation ◽  
Simulation Monte Carlo ◽  
Boltzmann Method

Gas flows in micro-electro-mechanical systems (MEMS) owing to the small size of the systems possess a relatively large Knuden number and usually belong to the slip and transitional flow regimes. This paper employs three schemes, namely the direct simulation Monte Carlo (DSMC) method, information preservation (IP) method, and the lattice Boltzmann method (LBM), to simulation micro-channel flows at three Knudsen numbers (Kn) of 0.0194, 0.194 and 0.388. The present LBM results are in agreement with those given by Nie et al. (2002), whereas they significantly differ from the DSMC (and IP) results as Kn increases. This suggests that the present version of LBM is not feasible to simulate the micro-channel flows in transition regime.

Particle Methods for the Boltzmann Equation

Acta Numerica ◽  
1995 ◽  
Vol 4 ◽  
pp. 417-457 ◽  
Author(s):  
Helmut Neunzert ◽  
Jens Struckmeier
Keyword(s):  
Semiconductor Device ◽  
Rarefied Gas ◽  
Hard Spheres ◽  
Kinetic Equations ◽  
Device Simulation ◽  
Particle Methods ◽  
Gas Flows ◽  
Real Gas ◽  
Rarefied Gas Flows ◽  
Real Gas Effects

In the following chapters we will discuss particle methods for the numerical simulation of rarefied gas flows.We will mainly treat a billiard game, that is, our particles will be hard spheres. But we will also touch upon cases where particles have internal energies due to rotation or vibration, which they exchange in a collision, and we will talk about chemical reactions happening during a collision.Due to the limited size of this paper, we are only able to mention the principles of these real-gas effects. On the other hand, the general concepts of particle methods to be presented may be used for other kinds of kinetic equations, such as the semiconductor device simulation. We leave this part of the research to subsequent papers.

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