Investigation of Turbulent Flow over Dunes

Abstract

The turbulent‐flow field above dunes is predicted with equations describing the transport of the kinetic energy of turbulence (k) its rate of dissipation (ε), and algebraic relations derived from a second‐moment turbulence closure (Algebraic Stress Model). The resulting set of expressions jointly with the identified boundary conditions are solved with a computer code based on a finite‐difference solution that uses the PISO algorithm to handle the coupling between the continuity and momentum equations to obtain mean velocity and turbulent‐stress profiles in the flow field, turbulent kinetic energy, and pressure and shear stress distributions over the dune surface. Estimates of flow resistance are obtained by integrating the pressure and shear stress distributions acting on the dune surface. Predictions compared well with detailed data of experiments on turbulent open‐channel flow over dunes and with experimental data of total flow resistance.