Abstract

Accurate prediction of high-speed compressible turbulent flows remains one of the most significant challenges in Computational Fluid Dynamics (CFD), especially in the realm of hypersonic vehicle design. These flow regimes involve significant aerodynamic heating and shock-wave boundary layer interactions (SBLI) which remain a significant challenge for the current CFD prediction capabilities. While Direct Numerical Simulation (DNS) and Large-Eddy Simulation (LES) provide high-fidelity solutions, their computational demands limit their usability, making the Reynolds-Averaged Navier-Stokes (RANS) equations an efficient alternative for many industrial aerodynamic applications. Traditional RANS techniques, while computationally efficient, often provide limited accuracy in high-speed flows due to the presence of strong compressibility effects and density variations. This dissertation contributes to the advancement of one-equation Spalart-Allmaras (SA) and Wray-Agarwal (WA) linear eddy viscosity turbulence models, with emphasis on the high-speed flow application of the WA model. All turbulence models and their proposed compressibility corrections are implemented in the open-source CFD solver Stanford University Unstructured (SU2). Following implementation, verification and validation was conducted for many canonical benchmark cases from the NASA Turbulence Modeling Resource (TMR) website to assess the model’s accuracy and reliability. The proposed WA model modifications include incorporation of the Catris and Aupoix compressible boundary layer corrections and a newly developed variable-property compressible law of the wall correction (WA-CCLoW). These enhancements are derived, and the improved WA model’s performance is evaluated on an extensive suite of experimental supersonic/hypersonic NASA benchmark cases. Furthermore, Uncertainty Quantification (UQ) techniques are employed to assess the sensitivity of the closure coefficients of the turbulence model on the solution and thereby fine-tuning the model coefficients for high-speed flow predictions. This research lays a foundational framework for the continued development and advancement of one-equation RANS turbulence models as practical and computationally affordable tools for hypersonic flow simulations. By combining the classical fluid dynamics theory with complex turbulence model development, uncertainty quantification, and sensitivity analysis, this dissertation contributes to the broader scope of advancing the RANS predictions in the field of high-speed aerodynamics.

Committee Chair

Ramesh Agarwal

Committee Members

David Peters; Mark Meacham; Richard Axelbaum; Swami Karunamoorthy

Degree

Doctor of Philosophy (PhD)

Author's Department

Mechanical Engineering & Materials Science

Author's School

McKelvey School of Engineering

Document Type

Dissertation

Date of Award

8-18-2025

Language

English (en)

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