Computation of the details of energy losses in non-homogeneous turbulent flows in open-channel transitions

In the most cases of the transitions, the energy losses are so complex that it is not easy to define specific relationships for them, and the energy losses are usually determined empirically or experimentally. In this study, explicit relationships for the total mechanical energy loss and the roughness coefficient in non-homogeneous turbulent flows in open-channel transitions are developed through theoretical analysis and numerical simulation. Before applying the analytical relationships in the expansive transitions, the distributions of the mean velocity are investigated, which indicates that the asymmetric flow pattern occurs for the expansion ratios greater than ۱.۵, and the flow separates along either of two sidewalls, so it can result in significant loss due to eddy formation. Then, the mechanical energy losses are obtained and the effect of the various parameters is studied. Finally, a better understanding of the details of the mechanical energy loss mechanism in the irregular open channels is achieved. In such a way that the energy losses can be predicted independently of the laboratory measurements, with the help of the proposed analytical model and numerical tools.

Keywords:

energy loss , roughness coefficient , non-homogeneous turbulent flows , analytical model , open-channel transitions , numerical simulation