Evaluation Of M-Y Closure Model In Tidal Estuary With TurbulenceData From High-resolution Current Profiler

Abstract

A high-resolution current profiler (HRCP), which belongs to a pulse-topulse coherent Doppler sonar, has been used to measure accurate vertical profiles of turbulence parameters, such as the Reynolds stresses, eddy viscosity, production and dissipation rates, etc., and to test the parameterization of dissipation rate and eddy viscosity. The HRCP and automatic ascendingldescending CTD are deployed in a tidal shallow estuary. The current near the bed during the ebb tide is smaller than during the flood tide. Thus, the bed-generated turbulence during the ebb is weak compared with that during the flood. The velocity profiles are almost linear during the ebb, whereas the profiles fit to a logarithmic form during the flood. The rate of TKE production is not balanced by dissipation even near the bottom. The constant of proportionality B1 in the dissipation model is much larger than 16.6 used in M-Y model. The results of numerical simulation using M-Y model are compared with the mean and turbulence data deduced by HRCP. l Introduction Many industrial or domestic wastes are discharged to coastal waters. Since estuaries often lie within regions of high population and industrial activity, the effect of discharged waste on the water quality, biological productivity, and species diversity in estuaries have become a topic of increasing concern. The flow in tidal estuaries is very complex, particularly due to tidal oscillations associated with changes in depth, mean velocity, direction of flow and density gradients affected by salt, heat and suspended particles. Moreover, the flow is very sensitive to the vertical mixing by turbulence. Therefore, it Transactions on the Built Environment vol 70, © 2003 WIT Press, www.witpress.com, ISSN 1743-3509