Publication Date


Document Type


Committee Members

Mitch Wolff, Ph.D. (Committee Chair); Anthony N. Palazotto, Ph.D., P.E. (Committee Co-Chair); George P. Huang, Ph.D. (Committee Member)

Degree Name

Master of Science in Mechanical Engineering (MSME)


This study characterizes the functional dependence of drag on Reynolds number for a deformed vacuum lighter-than-air vehicle. The commercial computational fluid dynamics (CFD) code, FLUENT, is used to preform large eddy simulations (LES) over a range of Reynolds numbers; only Reynolds numbers less than 310,000 are considered. While the overarching goal is drag characterization, general flow-field physics are also discussed, including basic turbulence spectra. All large eddy simulations are preceded by a Reynolds-averaged Navier-Stokes (RANS) simulation using Menter’s shear stress transport (SST) model. The precursor RANS simulation serves to (1) provide realistic initial conditions, (2) decrease the time needed to achieve a statistically averageable state, (3) assess near-wall mesh resolution, and (4) provide an estimate of the integral length scale. After achieving a statistically averageable state, each LES is integrated for at least 5 through-flow times. For sub-grid scale modeling, turbulence kinetic energy (TKE) transport is enabled, as it is the only model which allows for direct assessment of TKE resolution; all simulations resolve at least 80% of the total TKE at every point in the computational domain. To validate this study, all calculated drag coefficients are compared with experimental wind tunnel data.

Page Count


Department or Program

Department of Mechanical and Materials Engineering

Year Degree Awarded


Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.