Generalized Algebraic Relation For Predicting Developing Curved Channel Flow With A K Epsilon Model Of Turbulence

Download or read book Generalized Algebraic Relation for Predicting Developing Curved Channel Flow with a K-epsilon Model of Turbulence written by and published by . This book was released on 1981 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Using algebraic approximations for the Reynolds stress equations a general expression has been derived for C/sub .mu./ in .nu./sub t/ = C/sub .mu./ k2/epsilon which accounts simultaneously for the effects of streamline curvature and pressure-strain in the flow, including wall-induced influences on the velocity fluctuations. The expression derived can be shown to encompass smilar but more specific formulations proposed by Bradshaw, Rodi, and Leschziner and Rodi. The present formulation has been used in conjunction with a k-epsilon model of turbulence to predict developing, two-dimensional, curved channel flows where both curvature and pressure-strain effects can be large. Minor modifications to include the influence of curvature on the length scale of the flow near the walls produce a significant improvement in the calculations. While, in general, predictions are in good agreement with experimental measurements of mildly and strongly curved flows, the model tends to overpredict the kinetic energy of turbulence in the inner-radius (convex) wall region. This is attributed to a breakdown of the assumption that u/sub i/u/sub j//k is a constant in the derivation of the general expression for C/sub .mu./. Most of the experimental results suggest the presence of a weak cross-stream motion due to Taylor-Goertler vortices which cannot be resolved by the calculation scheme. Despite its limitations the present formulation provides a degree of generality not previously available in two-equation modeling of turbulent flows.