Stratified flow past a sphere at moderate Reynolds numbers

A numerical study of stably stratified flows past spheres at Reynolds numbers Re=200 and Re=300 is reported. In these flow regimes, a neutrally laminar induces distinctly different near-wake features. However, the behaviour changes significantly as stratification increases suppresses scale vertical displacements fluid parcels. Computations for range Froude Fr∈[0.1,∞] show that number decreases, patterns both become similar. The representative simulations lee-wave instability Fr=0.625 two-dimensional vortex shedding Fr=0.25 regimes are illustrated single tandem spheres, thereby providing further insight into dynamics bluff bodies. particular, reported examines relative influence viscosity on dividing streamline elevation, wake structure separation. solutions Navier-Stokes equations in incompressible Boussinesq limit obtained unstructured meshes suitable involving multiple accomplished using finite volume, non-oscillatory forward-in-time (NFT) Multidimensional Positive Definite Transport Algorithm (MPDATA) based solver. impact validity approximations, especially cases exhibiting strong stratification, also discussed. Qualitative quantitative comparisons with available laboratory experiments prior studies confirm approach.