Investigation on subsonic to supersonic flow around a sphere at low Reynolds number of between 50 and 300 by direct numerical simulation

A computational code adopting immersed boundary methods for compressible gas-particle multiphase turbulent flows is developed and validated through two-dimensional numerical experiments. The turbulent flow region is modeled by a second-order pseudo skew-symmetric form with minimum dissipation, while the monotone upstream-centered scheme for conservation laws (MUSCL) scheme is employed in the shock region. The present scheme is applied to the flow around a two-dimensional cylinder under various freestream Mach numbers. Compared with the original MUSCL scheme, the minimum dissipation enabled by the pseudo skew-symmetric form significantly improves the resolution of the vortex generated in the wake while retaining the shock capturing ability. In addition, the resulting aerodynamic force is significantly improved. Also, the present scheme is successfully applied to moving two-cylinder problems.

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Abstract

Empirical formulas for the 14 MeV (n,p) and (n, a) cross sections given by Levkovskii were modified separately in three ranges of mass number, in each of which, coefficients modifying Levkovskii's formulas were determined by least-squares fitting to experimental cross sections. The resulting modified formulas yielded cross sections representing markedly smaller chi-square deviations from experimental values, and moreover gathered closer to unity, compared with calculation using Levkovskii's original formulas.