Thermal convection in a closed water body with aquatic plants

In some closed water bodies with little inflow and outflow, because the flow is gentle, hydraulic characteristics are different from a river or an irrigation canal. When there is no disturbance, fluid is stratified based on vertical density distribution. In these bodies, the main dynamics of the water environmental substance depends on the wind current on a water surface induced by the mechanical disturbance and a convective flow induced by a thermal disturbance. We focused on a convective flow induced by the thermal disturbance. The mechanism of the generation and development processes of the gravity convection by surface cooling was investigated through the numerical experiment and the hydraulic experiment for the closed water body covered with aquatic plants. As the results, a density difference was generated horizontally because of the coverage of the water surface, and the horizontal convection was caused. This effect influenced the development speed of convection cells in a vertical direction, and the development speed of a mixture layer has increased.