Turbulence Modelling of Three Dimensional Flow in Rectangular Harbours

Details of the numerical model results of the layer integrated model for rectangular harbours with Large aspect ratios (i.e.L/B=1/4 to 4/1),using the two equation and zero equation turbulence models are discussed. For the zero equation turbulence model, the simple mixing length model was deployed to calculate the horizontal eddy viscosity coefficient in the numerical test whereas for the two equation turbulence model, the depth integrated k-ε turbulence model was used for this purpose. Likewise, the mixing length and the layer intergrated k-ε model were used to determine the vertical eddy viscosity. The model was first applayed for the channel flow and a reasonable areement between the predicted values and experimental data was achieved. The model was then applied for the model harbunes. The no-slip and partial -slip closed boundary representation were considered to evaluate the socond derivative for the horizontal turbulance diffusion term adjacent to walls. The numerical model results have been shown that, firstly the predicted flow patterns of the k-ε model were almost similar to those of the mixing length turbulance model. Secondly, the flow patterns in different layers were similar and the horizontal velocity distribution showede very small variations through the water colimn. Finally, it has generally been found that the numerical model results of the k-ε turbulence model were in very good agreement with the experimental results.

Keywords:

numerical model , turbulence modelling , tidal flow , rectangular harbours , layer integrated equations , closed boundary conditions , secondary circulation