NTRS - NASA Technical Reports Server

Back to Results
Computational Study of Separating Flow in a Planar Subsonic DiffuserA computational study of the separated flow through a 2-D asymmetric subsonic diffuser has been performed. The Wind Computational Fluid Dynamics code is used to predict the separation and reattachment behavior for an incompressible diffuser flow. The diffuser inlet flow is a two-dimensional, turbulent, and fully-developed channel flow with a Reynolds number of 20,000 based on the centerline velocity and the channel height. Wind solutions computed with the Menter SST, Chien k-epsilon, Spalart-Allmaras and Explicit Algebraic Reynolds Stress turbulence models are compared with experimentally measured velocity profiles and skin friction along the upper and lower walls. In addition to the turbulence model study, the effects of grid resolution and use of wall functions were investigated. The grid studies varied the number of grid points across the diffuser and varied the initial wall spacing from y(sup +) = 0.2 to 60. The wall function study assessed the applicability of wall functions for analysis of separated flow. The SST and Explicit Algebraic Stress models provide the best agreement with experimental data, and it is recommended wall functions should only be used with a high level of caution.
Document ID
Document Type
Technical Memorandum (TM)
DalBello, Teryn
(Toledo Univ. OH, United States)
Dippold, Vance, III
(NASA Glenn Research Center Cleveland, OH, United States)
Georgiadis, Nicholas J.
(NASA Glenn Research Center Cleveland, OH, United States)
Date Acquired
September 7, 2013
Publication Date
October 1, 2005
Subject Category
Report/Patent Number
Funding Number(s)
WBS: WBS 22-781-30-70
Distribution Limits
Work of the US Gov. Public Use Permitted.
No Preview Available