Heat Loss from Sidearms of Cooling Lakes

Gravity currents arising from thermally-induced buoyancy in sidearms of cooling lakes are analyzed with a numerical model that is based in part on experimental observations. The boundary layer forms of the momentum and thermal energy equations are solved by a variation of the Karman-Pohlhausen technique. The numerical model incorporates the coupling between the momentum and thermal energy equations that results from thermally-induced buoyancy forces that diminish as cooling of the water surface occurs through natural heat transfer processes. The numerical model results for surface heat-loss rate from the sidearm, entrance discharge, and surface temperature drop along the sidearm are shown ultimately to depend on the Grashof number and modified Prandtl number, and the results are compared with experimental data. Application of the numerical results demonstrates the significant heat loss that can occur from a sidearm in a cooling lake.