(325h) Adaptive Large Eddy Simulation Of Subcritical Flow Past And Heat Transfer From Solid And Porous Spheres

Adaptive LES (large-eddy simulation) is used to compute the drag coefficient C_D and Nusselt number Nu for turbulent flow past a sphere with a constant surface temperature at Reynolds numbers in the range 400-20000, corresponding to the subcritical (laminar separation) regime. Both domain- and grid-independence are established for the flows. Comparisons are made between the computations and standard correlations for C_D and Nu representing experimental data from several sources. The results for the solid sphere agree well with the correlations, with discrepancies of the same order as the experimental precision found in the literature. The solid sphere results are used as a benchmark for evaluating our approach to incorporating flow around porous particles into CFD simulations of diffusion, reaction and heat transfer in assemblies of particles. Since both types of computation in turn serve as models for the development of grids and approaches for flow through random (or semi-ordered, at best) fixed beds of particles, no symmetry was assumed and all computations were carried out in 3D, integrating in time until statistical steady-state was attained.