Natural Convection in Near Shore Waters Subject to Periodic Thermal Forcing

The variation of water depth across shore in nearshore waters results in differential heating which generates natural convection. Field observations have demonstrated the significance of this buoyancy-driven flow in promoting exchanges across shore. The present investigation is concerned with natural convection in nearshore waters subject to periodic thermal forcing at the water surface. Flow response at different stages of the periodic forcing has been illustrated by isotherms and streamlines from numerical simulations, and an evident effect of phase delay is observed. Analysis on the time series of horizontal exchange rate reveals that the phase delay of flow response decreases with increasing period. For sufficiently large period, the heating and cooling phase is characterized by low and high values of horizontal exchange rate respectively.