Abstract
During heating season, hydrodynamic behavior of the thermocline in lakes and reservoirs is predominantly affected by the combined action of the stabilizing buoyancy flux due to solar radiation and the mechanical stirring due to wind shear stress. The present paper examines the entrainment process in such a situation experimentally and theoretically. In a physical model, the oscillating-grid turbulence and the stabilizing buoyancy flux are simultaneously supplied to the upper surface of a two-layer thermal stratification system and the resultant entrainment process is investigated. The entrainment rate is related to an overall Richardson number. The turbulent structure is also analyzed by considering the energy balance in the present system. Applying the entrainment law, we get an analytical solution of the equilibrium condition where the mechanical disturbance energy just balances the stabilizing effect of the buoyancy flux.
