Incorporating vibrational excitation in a hybrid particle-continuum method

A modular particle-continuum (MPC) method is extended to model vibrational excitation to simulate hypersonic steady-state flows that exhibit regions of collisional non equilibrium in a mainly continuum flow field. This method loosely couples a DSMC code to an implicit Navier-Stokes solver. By limiting our study to steady-state flows, bot time-step and cell size are decoupled between methods. Control of statistical scatter and information transfer between modules is described. Hypersonic flow over a 2-D cylinder is simulated with different physical models.Results from DSMC, CFD, and the MPC method are presented and compared. The agreement in vibrational temperature between DSMC and the MPC method decreases as the size of the continuum domain increases,which may be due to the difference in macroscopic relaxation rates computed in DSMC and CFD. Other flow variables and surface properties remain in excellent agreement between DSMC and the MPC method. The MPC simulation results are obtained using less than half the computational time compared to full DSMC while also decreasing the memory requirements.