Large Eddy Simulation of Flow Over a Heated Sphere

This study investigates flow over a heated sphere at a Reynolds number of 19,300 using Large Eddy Simulation (LES) with the Wall-Adapting Local Eddy-Viscosity (WALE) sub-grid scale (SGS) model, chosen for its superior capability to capture near-wall turbulence without the need for additional wall functions. The analysis employs second-order temporal and spatial discretization schemes to ensure numerical accuracy while minimizing diffusion. A computational domain was designed to encompass the sphere and a sufficient surrounding flow field, with a fine grid resolution. The study integrates a detailed validation process, comparing simulation results against high-resolution Particle Image Velocimetry (PIV) data, which serves as a benchmark for velocity profiles. OpenFOAM’s pimpleFoam solver, a transient, pressure-based solver for incompressible turbulent flows, was modified and used for all the simulations. Boundary conditions for velocity included turbulent intensity specified at the inlet, fully developed flow at the outlet, and no-slip conditions at the sphere surface and walls, ensuring accurate representation of physical conditions. Boundary conditions for temperature included fixed value of 301 K specified at the inlet and pipe wall, fully developed conditions at the outlet, and a constant wall temperature (407 K) at the sphere surface. Grid independence was verified using the Grid Convergence Index (GCI), ensuring reliability of the results. The simulation outcomes align closely with experimental data that is present in the literature with a minimal relative error of 4.23% for velocity near the sphere wall, demonstrating the WALE model’s effectiveness in resolving turbulence characteristics.