Second order modeling of turbulent flows
Abstract
Equations for the first and second order quantities (the variances and fluxes) are formed and the third order terms that appear in these equations are modeled in terms of the first and second order quantities. The equations for the second order quantities are usually supplemented by one or more equations for something equivalent to a length scale. The resulting set of equations is then solved on a computer by timestepping. Second order modeling should be contrasted with the mixing length approach, which could be called first order modeling. Flaws in the mixing length approach are reviewed as well as the cost of using second order models.
 Publication:

Von Karman Inst. for Fluid Dynamics: Prediction Methods for Turbulent Flows
 Pub Date:
 1979
 Bibcode:
 1979pmtf.vkif.....L
 Keywords:

 Computational Fluid Dynamics;
 Eddy Viscosity;
 Flow Equations;
 Mathematical Models;
 Turbulent Flow;
 Vorticity Transport Hypothesis;
 Buoyancy;
 Flow Velocity;
 Isotropy;
 Mixing Length Flow Theory;
 Reynolds Stress;
 Schwartz Inequality;
 Fluid Mechanics and Heat Transfer