Boundarylayer computational model for predicting the flow and heat transfer in sudden expansions
Abstract
Fully developed turbulent and laminar flows through symmetric planar and axisymmetric expansions with heat transfer were modeled using a finitedifference discretization of the boundarylayer equations. By using the boundarylayer equations to model separated flow in place of the NavierStokes equations, computational effort was reduced permitting turbulence modelling studies to be economically carried out. For laminar flow, the reattachment length was well predicted for Reynolds numbers as low as 20 and the details of the trapped eddy were well predicted for Reynolds numbers above 200. For turbulent flows, the Boussinesq assumption was used to express the Reynolds stresses in terms of a turbulent viscosity. Nearwall algebraic turbulence models based on Prandtl'smixinglength model and the maximum Reynolds shear stress were compared.
 Publication:

NASA STI/Recon Technical Report N
 Pub Date:
 July 1986
 Bibcode:
 1986STIN...8721303L
 Keywords:

 Boundary Layer Equations;
 Expansion;
 Finite Difference Theory;
 Heat Transfer;
 Laminar Flow;
 Separated Flow;
 Turbulent Flow;
 Turbulent Mixing;
 Mathematical Models;
 NavierStokes Equation;
 Predictions;
 Reynolds Number;
 Turbulence Models;
 Viscosity;
 Fluid Mechanics and Heat Transfer