Numerical investigation of flows with three-dimensional separation

A. Gross, H. F. Fasel

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

When low aspect ratio geometries such as submarines, torpedoes, or missiles are operated at large angles of attack three-dimensional separation will occur on the leeward side. Separation increases losses and can result in undesirable unsteady forces. An improved understanding of three-dimensional separation is desirable as it may open the door to new methods for the control or prevention of separation. Numerical simulations of three-dimensional separation can provide detailed insight into instability mechanisms and the resultant flow structures. For most technical applications the Reynolds numbers are too high for direct numerical simulations and lower-fidelity approaches such as hybrid turbulence models become attractive. In this paper a new hybrid turbulence model blending strategy is proposed that adjusts the model contribution according to the local grid resolution. The strategy is validated for two-dimensional plane channel flow at Reτ= 395 and for the Stanford asymmetric diffuser which features a turbulent three-dimensional separation. The model is then employed for simulations of a hemisphere-cylinder geometry at 10 and 30 degrees angle of attack. The simulations demonstrate satisfactory model performance over a wide range of Reynolds numbers (5×103< ReD< 5×106). A nose separation bubble is captured for the lower Reynolds numbers and leeward vortices are observed for 30deg angle of attack regardless of Reynolds number. Different from, e.g., hemisphere-cylinder geometries asymmetric separation and roll-instability were reported for non-body-of-revolution geometries. The paper concludes with a brief discussion of simulations that were carried out for the Virginia Tech ellipsoid model at ReL= 20, 000.

Original languageEnglish (US)
Title of host publication51st AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition 2013
StatePublished - Aug 19 2013
Event51st AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition 2013 - Grapevine, TX, United States
Duration: Jan 7 2013Jan 10 2013

Publication series

Name51st AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition 2013

Other

Other51st AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition 2013
CountryUnited States
CityGrapevine, TX
Period1/7/131/10/13

ASJC Scopus subject areas

  • Space and Planetary Science
  • Aerospace Engineering

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    Gross, A., & Fasel, H. F. (2013). Numerical investigation of flows with three-dimensional separation. In 51st AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition 2013 (51st AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition 2013).