NONLINEAR EDDY-VISCOSITY MODELING OF TRANSITIONAL BOUNDARY-LAYERS PERTINENT TO TURBOMACHINE AERODYNAMICS

The predictive performance of three low-Reynolds-number turbulence mod els, one based on the linear (Boussinesq) stress-strain relationship a nd two adopting cubic forms, is examined by reference to transitional flat-plate boundary layers subjected to streamwise pressure gradient a nd moderate free-stream turbulence, the latter causing bypass transiti on. One of the cubic models involves the solution of two transport equ ations, while the other involves three equations, one of which relates to the second invariant of turbulence anisotropy. The investigation d emonstrates that, for the conditions examined, the non-linear models r eturn a more credible representation of transition than the linear var iant, although none of the models may be said to be entirely satisfact ory. Thus, while non-linear modelling shows promise and offers inheren t advantages through the use of a more general stress-strain linkage a nd elaborate calibration, further refinement is needed in the present cubic variants for transitional Bows. (C) 1998 Elsevier Science Inc. A ll rights reserved.