PREDICTION OF TURBULENT FLOWS IN DREDGED TRENCHES

Data from turbulent flows over steep-sided trapezoidal trenches and a backward-facing step in an open channel were used to assess the perfor mance of three alternative models of turbulence viz. the industry-stan dard kappa-epsilon model, a second-order closure which is linear in th e Reynolds stresses and another which is quadratic in the same quantit ies. The computations were carried out on body-fitted coordinates and were carefully checked for numerical accuracy. It is demonstrated that the mean-flow parameters are predicted equally well by all models but that the details of the turbulence structure are best captured by the second-order closures, The significance of these results to the pract ical prediction of trench flows is discussed.