Numerical study on temporal evolution of velocity in paddlewheel-induced pond circulation

Based on the finite volume method of computational fluid dynamics and k-e turbulence model equations, combines the volume of fluid method with the moving mesh method to deal with air-water interface, a 3d unsteady paddlewheel-induced pond circulation while running and shutting off the paddlewheel machineries across the air-water interface is simulated in this paper. In this simulation, some monitory points are arranged at the section far ahead and near the front of the aerator to monitor the evolution of velocity in the pond circulation. Growing and decaying characteristics of velocity are analyzed. Analysis result shows that: At the location near the front of the aerator, growing characteristics of velocity are significantly different between upper layer and lower layer; the main decaying characteristic of velocity is that velocity decays rapidly after the moment when machineries shut off. At the location far ahead the aerator, the growing characteristic curves of velocity fit for the quadratic polynomial function, and the decaying characteristic curves of velocity fit for the exponential function.