Simulations Of Hypersonic Rarefied Gas Flows Using Dsmc Mlg

Simulations of Hypersonic Rarefied Gas Flows Using DSMC-MLG.

The combined Direct Simulation Monte Carlo (DSMC) and Monotonic Lagrangian Grid (MLG) methodologies are used on the massively parallel Connection Machines CM-5 to solve for the properties of a low density hypersonic flow through a channel containing a wedge. Numerical issues related to grid generation around the obstacle, the effects of resolution in terms of the simulated to actual particle ratio, and the use of time-averaging to obtain a statistically converged solution are discussed. A method is presented for quantifying the effects of the grid on the solution. The flow field shows many important aerodynamic features, such as shock waves, boundary layers, expansion fan, and their interactions. Since the flow is so rarefied, these structures are diffuse compared to what is expected in a continuum flow. For example, the reattachment shock behind the trailing edge of the wedge degenerates into a diffuse viscous layer. Other low density effects include the velocity slip, which peaks near the leading edges where the density is low, and temperature jump of the gas adjacent to the solid surfaces, which is highest at the entrance of the channel and decreases further downstream. The calculated skin friction and heat transfer agree well with the Reynolds analogy for boundary layer flow. The computed pressure distributions along the wall are consistent with hypersonic viscous theory and other DSMC calculations.

AIAA Journal

30th AIAA Thermophysics Conference