An extended depth-averaged turbulence model for flow constricted by cofferdams

An extended depth-averaged k-epsilon turbulence model is proposed for simulating the now in a channel constricted by cofferdams. In the present paper, the coefficient C-mu is expressed as a function of shear strain rate scale S and vorticity scale Omega to eliminate the excessive production of turbulent kinetic energy around a stagnation point. The model constants C-1, C-2 in the epsilon-equation are modified as functional forms of time scales G/epsilon and Sk/epsilon to account for nonequilibrium effects. Three-dimensional effects are considered by modifying the friction coefficient in bottom shear stresses. The computed solutions are compared with experimental data. The agreement between the calculated and experimental results is quite satisfactory.