Parallel Computation of Fully Coupled Hypersonic Radiating Flowfield Using Multiband Model

摘要

Parallel computation of a fully coupled, strongly radiating hypersonic flow field is carried out. A detailed multi-band model is used in the radiation calculation. The radiative heat flux is calculated using one- (tangent-slab) or two-dimensional approximations in radiative transfer, or by considering three-dimensional radiative transfer directly. To reduce the vast computing time due to a spectrally detailed and multidimensional radiation calculation, a parallel computation is employed. The strategy in the parallel implementation of the code is to divide the wavelength range in the multiband model into groups of the same number of available processors, instead of dividing the computational domain. Calculations are carried out for the flowfield over hemispheres at a speed of 15.24 km/s and an altitude of 57.9 km. The computed results are compared with those obtained in previous studies. A fair agreement of the shock standoff distance with the existing results is shown for several different radii. However, the present result gives a substantially larger radiative heat flux value at the stagnation point for smaller radius cases. This is because the radiative heat transfer from the wavelength region shorter than 1400 A is found to be optically thick in the shock layer and becomes dominant in these smaller radius cases. The parallel code developed in the present study achieves a computational speed of approximately 20 giga-floating point operations per second using 128 processors on the SGI ORIGIN 2000. The converged solutions for strongly radiating flowfield can be obtained within a feasible computing time.