A parallelized hybrid N-S/DSMC-IP approach based on adaptive structured/unstructured overlapping grids for hypersonic transitional flows

A new hybrid N-S/DSMC-IP approach based on adaptive structured/unstructured overlapping grids is proposed and implemented to simulate hypersonic transitional flows. This approach uses the N-S method based on structured grids and the DSMC-IP method based on unstructured grids in the simulation of continuum and rarefied flow fields. The adaptive overlapping grid method is utilized and the interface between the continuum and rarefied regions is partitioned using KnGL number. The information in the different regions is strongly coupled to the continuum/rarefied interface, and the values in the coupling cells are interpolated with the weight coefficients. Finally, an adaptive parallel strategy is proposed to further improve computational efficiency. This hybrid approach combines the advantages of the structured grid and unstructured grid methods, meaning it can investigate the various characteristics of transitional flow fields with high efficiency and accuracy, while also enhancing the approach's fitness. This hybrid approach is implemented to simulate the continuum/rarefied hypersonic transitional flows around a cylinder and a nozzle; with the results indicating that the computational speed for this hybrid approach is much higher than for the DSMC-IP method and that it can be used to investigate variation in the characteristics of continuum/rarefied regions in transitional flows. Therefore, it is an efficient algorithm for the investigation of hypersonic transitional flows.