A vorticity transport closure method for turbulent reacting flows
Abstract
A closure method for variable density turbulent reacting flows is proposed. The vorticity transport theory is herein extended to the case of compressible flows. Specifically, turbulent vorticity and dilatation transport laws have been derived using a Lagrangian analysis of the vorticity transport equation in which velocityvelocity gradient correlations are analyzed keeping compressibility and vortex stretching effects. The complete set of closed equations includes a new mean dilatation (barTheta) transport equation and a turbulent dilatation fluctuation intensity (eta) equation. It is shown that the closure method can also be applied through a primitive variable formulation. In this case, in contrast to the standard eddy viscosity models, the averaged momentum equation has additional terms representing the mechanism of vorticity stretching which is known to be an important boundary layer phenomenon. In addition to the turbulence closure, a turbulent combustion model based on a vorticity dissipation time scale is proposed. To close the turbulent reaction rate expression, a species fluctuation intensity (xi(sub i)) equation is derived as well as species mass balance (barY(sub i)) equation. These equations reflect the rich interaction between turbulence and chemistry. The vorticity transport closure method and the vorticity dissipation combustion model are applied to the internal combustion engine cylinder flow. An implicit finite difference method with full multigrid acceleration is used to solve the governing equations. The calculated results are in good agreement with available experimental data.
 Publication:

Ph.D. Thesis
 Pub Date:
 1992
 Bibcode:
 1992PhDT........47K
 Keywords:

 Compressible Flow;
 Computational Fluid Dynamics;
 Reacting Flow;
 Transport Theory;
 Turbulence Models;
 Turbulent Combustion;
 Turbulent Flow;
 Vorticity;
 Combustion Physics;
 Eddy Viscosity;
 Finite Difference Theory;
 Internal Combustion Engines;
 Lagrangian Function;
 Reaction Kinetics;
 Vortices;
 Fluid Mechanics and Heat Transfer