Date of Award

8-2026

Degree Type

Report

Degree Name

Master of Science (MS)

Department

Mechanical and Aerospace Engineering

Committee Chair(s)

Som Dutta

Committee

Som Dutta

Committee

Douglas Hunsaker

Committee

Nadia Kouraytem

Abstract

Reynolds-Averaged Navier--Stokes (RANS) simulations are widely used for predicting aerodynamic performance in engineering applications but often require substantial computational time to achieve convergence, particularly for bluff-body flows characterized by large-scale separation and wake formation. Improving the initialization of CFD simulations offers a practical approach for reducing computational cost without modifying the underlying numerical algorithms. This study investigates the use of a surface-vorticity panel solver (FlightStream) to generate physically informed velocity fields for initializing steady RANS simulations in STAR-CCM+.

Two canonical bluff-body geometries are considered: a sphere at a Reynolds number of 5 X 105 and an isolated cube at a Reynolds number of 5.5 X 104. Grid-independent baseline RANS solutions are first established and validated against published reference data. Velocity fields computed using FlightStream are then mapped onto the RANS computational domain and used as initial conditions while maintaining identical mesh, turbulence model, and solver settings. The effectiveness of the proposed initialization strategy is evaluated by comparing iteration counts, wall-clock time, residual convergence, and drag coefficient predictions with those obtained using conventional uniform initialization.

This work extends previous research on panel-based initialization from streamlined airfoil geometries to bluff-body flows, where large separated wakes challenge potential-flow assumptions. The results provide insight into the applicability of panel-method initialization for accelerating steady RANS simulations of bluff-body flows.

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