2012 Volume 64 Issue 1 Pages 9-12
Two-equation models including the k-ε model are widely used for Reynolds-averaged Navier-Stokes simulations. However, the second model equation such as the dissipation rate equation has not been fully validated. In this work, the transport equation for the eddy diffusivity is investigated to better understand turbulence and improve turbulence models. The nonlocal eddy diffusivity representation for the turbulent scalar flux is first considered. A new length scale is introduced to express the local eddy diffusivity. The transport equation for the eddy diffusivity is derived using the length-scale equation. The transport equation is evaluated using a direct numerical simulation of turbulent channel flow and their physical meaning is investigated. [This abstract is not included in the PDF]