2-D Numerical Investigation Of Micro-Scale Flow Based On The Theory Of Molecular Dynamics

Two dimension flow simulation based on molecule movement (FSMM2D) is presented in this paper, which is developed from DSMC method.Firstly the basic concepts and theories of DSMC have been introduced. Then a general description of FSMM2D is provided. With the flowchart the program can be divided into six parts and it includes initial flow field, computation of molecular motion, boundary treatment, re-sort of molecular, sample and computation of molecular collision. Several cases have been simulated to certify the correctness of the program.DSMC method is improved using method of characteristics to modify the boundary condition and gets the goal as expected. Investigations on the selection of three key parameters are carried out. Results show that the best values for the number of sampling loop,the number of simulated particle per cell and the number of sub-cell are about eight,five and four respectively. Micro-plate layer, and flow through micro vertical plate are simulated and it is clear that the improved program with the optimal parameters can not only get the same results as those of other researchers but can greatly enhance the computational accuracy and efficiency.DSMC method inherently involves the restriction of statistical noise problem and IP method is an improvement algorithm of DSMC method. Descriptions of suppression of statistical noise and algorithm realization of IP method are provided. DSMC-IP method is a reasonable and reliable tool for simulation of low velocity micro flow through comparing and verifying several cases. Moreover, the advantage of this method is obvious and outstanding in computational resolution and efficiency.At the end of this paper the feasibility and possibility to enlarge the range of application of DSMC-IP method to structural grid with curvature geometry are discussed.