Effective viscosity in the simulation of spatially evolving shear flows with monotonic FCT models
Abstract
The global numerical diffusion of a model for the lowMachnumber simulation of free mixing layers is investigated. The numerical model solves the inviscid timedependent conservation equations for mass, momentum and energy, for ideal gases. The equations are solved using an explicit FluxCorrected Transport (FCT) algorithm, directional timestepsplitting techniques on structured grids, and appropriate inflow and outflow boundary conditions. Effective measurement of the numerical diffusion of the model in uniform grids is performed by comparison of the laminar spread of the simulated mixing layers with that predicted by boundary layer theory. The results show that the residual numerical diffusion of the FCT model can emulate physical viscosity for laminar shear flows at moderately high Reynolds numbers. The global numerical diffusion is not very sensitive to changes in freestream velocity ratio, and can be reduced in a predictable way by refining the grid spacing.
 Publication:

Naval Research Lab. Report
 Pub Date:
 December 1991
 Bibcode:
 1991nrl..reptY....G
 Keywords:

 Algorithms;
 Boundaries;
 Diffusion;
 Flow Equations;
 Fluid Dynamics;
 Free Flow;
 Inviscid Flow;
 Laminar Mixing;
 Shear Flow;
 Shear Layers;
 Simulation;
 Viscosity;
 High Reynolds Number;
 Mathematical Models;
 Momentum Theory;
 Numerical Analysis;
 Ratios;
 Residual Gas;
 Velocity;
 Fluid Mechanics and Heat Transfer