Date of Award
Spring 5-13-2024
Degree Name
Master of Science (MS)
Degree Type
Thesis
Abstract
Turbulence models play an important role in including the effect of turbulence in numerical simulation of turbulent fluid flows using the Reynolds-Averaged Navier-Stokes Equations of computational fluid dynamics (CFD). In this thesis, the performance of various well-known turbulence models, namely the Spalart-Allmaras (SA), Shear Stress Transport (SST) k-ω, and Wray-Agarwal (WA) models is examined by considering the external subsonic flow over three benchmark cases: (a) the Boeing bump, (b) the two-dimensional VT/NASA bump (BeVERLI hill), and (c) the three-dimensional VT/NASA bump, and the transonic internal flow in Sajben diffuser. The flow field in all these four test cases is characterized by a small region of separation behind the bump or due to shock/boundary layer interaction in the case of diffuser. One key goal of the investigation is to evaluate the performance of a relatively new WA model compared to the established SA and SST k-ω models. The commercial flow solver Ansys Fluent is employed in the computations. The results indicate that while all three turbulence models provide acceptable predictions, the WA model demonstrates superior performance in capturing the separation region in the three external flow cases, and the internal flow field and shock position in case of transonic flow in Sajben diffuser. Moreover, the WA model also exhibits advantage in that it is less dependent on the grid density. This study demonstrates the challenges in turbulence modeling for predicting the smooth body flow separation using the RANS equations and demonstrates the potential of the WA model as an accurate and efficient model for predicting external and internal turbulent flows.
Language
English (en)
Chair
Ramesh K. Agarwal
Committee Members
Swami Karunamoorthy, David A. Peters