MIXED CONTINUUM-RAREFIED FLOWS

by Dr. Roverto Roveda

Overview | Figures | Movies | Publications

Overview

This project involves creating a hybrid computational procedure to compute flows which are rarefied in some regions and fully continuum in others. Applications for such a computer code include both external and internal flows but particular emphasis is being placed on problems related to shuttle plume impingement on space stations. In the hybrid code the rarefied areas are modeled with Direct Simulation Monte Carlo technique which directly models the motions and collision of the molecules of the fluid. The continuum regions are modeled with a discrete velocity Euler solver. An important goal of the effort is to be able to handle unsteady flows with an adaptive approach which applies the two different methods to the appropriate regions.

Figures

Fig. 11 Shows adaptive regridding of multiple travelling shock waves.
The flow moves uniformly toward the specularly reflective, right wall at 400 m/s.
After 3000 time steps the wall acts as a piston moving to the left at 792.4 m/s.
Fig. 12 Shows adaptive regridding of traveling expansion wave .
Blue: Full DSMC calculation
Red: Adpative, hybrid, DSMC/ADV calculation
The flow is moving uniformly away from the wall at 400 m/s.
Fig. 13 Illustrates the nature of shear waves passing through a fixed ADV/DSMC interface.
Shown are tangential velocity profiles for the numerical simulation of the compressible Rayleigh problem,
a flat plate suddenly moved in its own plane.
Fig. 14 Shows a 2-D hybrid ADV/DSMC calculation consisting of supersonic jet flow
impinging on a vertical flat plate
The jet is created by pressure driven flow through a narrow slit.
Fig. 15 Shows temperature contour and initial placement of ADV and DSMC regions for simulation in Fig. 14.

Movies

Evolution of unsteady 2-D plume impinging on a small flate plate (266kB Mpeg)

Hybrid ADV-DSMC simulation of 1-D shocktube (1.12MB Mpeg)

Publications

R. Roveda, D. B. Goldstein, and P. L. Varghese
"A Combined Discrete Velocity/Particle Based Numerical Approach for Continuum/Rarefied Flows"
AIAA Paper 97-1006, Reno, NV, January 1997.: Text: postcript (125Kb); Figures: postcript (7.6Mb)
This work has been funded though the Regional/University Grant program of NASA Johnson Space Center. Last modified: February 28, 1997