Numerical Simulation of3D-Flow in an Open Channel by Mixing Length Model

A simple turbulence model is applied to close the Reynolds equations for three-dimensional turbulent flow in a rectangular channel. The model is based on the gcncralisaiion of PrEindll's mixing length hypothesis which introduces a mixing length tensor. Components of the mixing length tensor are related to the sizes of the largest turbulent eddies. Patankar & Spalding's procedure (1972) is applied to solve the boundary problem for the Reynolds equations numerically. The numerical scheme has overall second order accuracy. It also avoids oscillations in numerical solutions because of holding the maximum principle. The calculated velocity field is compared with data of measurements.