## Research Abstracts Online

January
2008 - March 2009

### University of Minnesota Twin Cities

Institute of Technology

Department of Aerospace Engineering and Mechanics

## PI: Thomas E. Schwartzentruber

### Particle Simulation Methods for Non-equilibrium Gas Flows

Non-equilibrium gas flows occur when insufficient molecular collision rates cause the continuum fluid equations to become inaccurate. This is the situation at very high altitudes where the atmospheric density is low and also at very small length scales (MEMS flows) where insufficient collisions occur over the length scale of interest. Particle simulation methods such as the Direct Simulation Monte Carlo (DSMC) method are able to simulate the Boltzmann equation and provide accurate results in these regimes. Particle methods are more computationally expensive than continuum (computational fluid dynamics, CFD) methods, however, the continual increase in parallel computing capability is allowing for particle methods to simulate increasingly complex problems of real engineering interest.

This project focuses on simulating the aerothermodynamic environment experienced by hypersonic planetary entry vehicles (capsules) at high altitudes. The project involves large-scale parallel DSMC simulations at intermediate altitudes in order to directly compare with continuum simulation results. Research also focuses on coupling continuum-CFD and particle-DSMC methods for multi-scale hypersonic flows that are both highly accurate and computationally efficient. The parallel implementation of such a multi-scale method is also an important aspect of the project.

### Group Members

Da Gao, Research Associate

Daniel Poniatowski, Graduate Student