Aspects of inlet boundary prescription for a turbulent flow field

Abstract

In the literature on turbulent flow various combinations of velocity, turbulence kinetic energy, and eddy viscosity models have been proposed for the inlet boundary to a flow field. There appears to be no rational criterion for specifying inlet boundary conditions. The present study proposes a criterion to select the inlet boundary conditions by treating the inlet boundary as a part of the flow field. Using this criterion, any prescribed variation of velocity, turbulence kinetic energy k, and rate of dissipation of kinetic energy ?, must satisfy the governing flow field equations at the inlet boundary. Analysis of previously used profiles of velocity, kinetic energy, and dissipation of kinetic energy in the literature indicates that most of these do not satisfy the flow field equations. To substantiate the importance of inlet boundary conditions, several reported numerical simulations using k-? turbulence models are reconsidered to determine if there is any linkage between the residual errors at the inlet boundary and the errors in the flow field simulation. Based on such an analysis, it is both logical and practical to hypothesize the inlet boundary as a part of flow field.