Methods of Ensuring Realizability for Non-Realizable Second Order Closures

摘要

Several methods of ensuring realizability for nonrealizable second order closuremodels are discussed. The well known isotropization of production (IP) model and the Launder, Reece, and Rodi (LRR) model are particularly studied for their wide application in engineering calculations. Ensuring realizability for these models will extend their applicability to more critical flow situations and reduce the numerical difficulties caused by the nonrealizability of the original models. Different methods of ensuring realizability are tested for several extreme flow situations. The suggested realizability modifications not only make the models realizable but also maintain the performance of the original models for realistic flows. The methods discussed in this paper can be straightforwardly applied to other nonrealizable models.