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| RGS3D |
RGS3D(3D Rarefied Gas dynamics Simulation software) is a DSMC simulation software to compute spatial distribution of density, temperature and pressure of neutral gas in two or three dimensional arbitrary geometry shape under from viscous flow to free molecule flow by new collision method.
Description of method
RGS3D is based on DSMC(Direct Simulation Monte Carlo) method which is a probabilistic method to solve Boltzmann equation in gas theory. RGS3D is a simulation software to compute the flow field of rarefied gas in various vacuum chambers. This module is applied to from viscous flow field to free molecule flow field by using the new collision method(U-system)[1][2]. The new collision method has been implemented to RGS3D. There are no restriction of mesh width depending on mean free path length by using this method. Weight algorithm is adopted to avoid statistical fluctuation in the case that the difference of densities between species would be very large.
[1] Usami, M. and Nakayama T., Intermolecular Collision Scheme of DSMC Taking Molecular Locations within a Cell into Account, Rarefied Gas Dynamics, AIP Conference Proceedings, Vol.663 (2003), pp.374-381.
[2] Usami, M. and Mizuguchi, K., DSMC Calculation of Vortex Shedding behind a Flat Plate with a New Intermolecular Collision Scheme, Rarefied Gas Dynamics, AIP Conference Proceedings, Vol.762 (2005), pp.686-691.
Input data
- Mesh data,grids and elements data, of Nastran fromat for two or three dimensional arbitrary mesh.
- Specify mass number and diameter of each gas species.
- Specify various boundary conditions for in/outflow boundaries and reflective wall.
- Specify chemical reactions in gas phase or on walls.
Output data
- Spatial distribution of density, temperature, pressure and velocity of each species
- Particle and energy fluxes of each species to the walls
Main specification
| Item | General description | |
| Numerical method | Direct Simulation Monte Carlo (DSMC) method | |
| Computational dimension | 2 dimension or 3 dimension | |
| Shape of computational mesh | triangle or quadrangle in 2 dimension. tetrahedron,pentahedron or hexahedron in 3 dimension | |
| Number of species | Unlimited (depends on capacity of memory) | |
| Number of sample particles | Unlimited (depends on capacity of memory) | |
| Shape of inlet | surface or hole | |
| Inflow condition | whether particle flux or pressure and temperature | |
| Shape of outlet | surface or hole | |
| Reflective condition on walls | specular, cos dist. or diffusive reflection | |
| Input | mass number, diameter of each species. in/outflow boundaries(flow rate, flow-in velocity dist.,reflective condition) | |
| Input by preprocessor | geometry data of spacial mesh, in/outflow boundary, wall temperature | |
| Output | time history of number of sample particles, density, temperature and pressure
of monitoring elements. spacial distribution of density, temperature, velocity and pressure for each species. incident particle and energy flux onto walls for each species. |
|
| Pre/Post processor | built-in(GUIM/PERSEUS) or other commercial Pre/Post software | |
| Interface | Universal file or NASTRAN format | |
| Input | grids, elements and boundary conditions | |
| Output | phisical quantities of each elements | |
| Environment | OS | UNIX、Linux、Windows98/NT/2000/XP |
| Capacity of memory | recomended over 512MB | |
| Capacity of HDD | recommended over 1GB | |
| Other function | + restart function + reflective condition for each species on walls + gas-phase reactions by using rate constants or activate energy + reactions on walls by using probability of reactions |
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Example
