A Reynolds Stress Model for Flows With Drag Reduction

A simple turbulence model has been proposed, which is based on the Reynolds stress equation and on the turbulence energy dissipation equation. By increasing the viscosity in the equations for the components of Reynolds stress in which the cross-stream velocity appears, the model is shown to be able to reproduce the main features of turbulent flows near walls when drag reducing polymers are present, namely: the changes in the velocity distribution, the increase in the streamwise and transverse fluctuating velocity components in the buffer zone, the decrease of the cross-stream component, and the spectacular increase in the length scale of near-wall turbulence. All the predictions of the model are in fair agreement with existing experimental data.