Sheared convection

Using direct numerical simulations, we have studied how increasing shear reorganizes the convective flow and changes the efficiency of heat and momentum transport [1]. As the shear strength grows relative to the buoyancy forcing, the large-scale convection rolls that dominate unsheared Rayleigh-Bénard convection are progressively broken down and replaced by more streak-like, shear-aligned structures, with a corresponding change in how heat is carried between the plates. We subsequently examined how this shear-buoyancy interplay depends on the Prandtl number [2], and how small-scale flow structures — not just the large-scale flow organization — contribute to the heat transport in sheared convection [3]. Bringing these results together, we derived normalized scaling relations for heat transport and wall friction in sheared Rayleigh-Bénard convection [4]. Within the tested periodic DNS, the ratio of imposed-shear strength to the unsheared convection-wind strength organizes the crossover from buoyancy-dominated to shear-dominated response; the framework requires the unsheared reference values and has not been validated outside the sampled parameter range.