The Wilcox 2006 stress - omega model ( also referred to as WilcoxRSM - w2006 ) has been implemented in the NASA Langley code CFL3D and used to study a variety of 2 - D and 3 - D configurations . It predicted a variety of basic cases reasonably well , including secondary flow in a supersonic rectangular duct . One- and two - equation turbulence models that employ the Boussinesq constitutive relation were unable to predict this secondary flow accurately because it is driven by normal turbulent stress differences . For the NASA trapezoidal wing at high angles of attack , the WilcoxRSM - w2006 model predicted lower maximum lift than experiment , similar to results of a two - equation model .