TY - JOUR
T1 - Numerical and experimental investigation of unsteady three-dimensional separation on axisymmetric bodies
AU - Gross, A.
AU - Jagadeesh, C.
AU - Fasel, H. F.
N1 - Funding Information:
This work was funded by the Office of Naval Research (ONR) under Grant No. N00014-10-1-0404 with Dr. R. Joslin serving as program manager. Compute time was provided by challenge Grant ONRDC07692C4Y. This work was supported in part by a grant of HPC resources from the Arctic Region Supercomputing Center.
PY - 2013/12
Y1 - 2013/12
N2 - The understanding of unsteady three-dimensional separation is lagging behind the understanding of two-dimensional separation due to its greater complexity and the limited amount of data for universal or canonical flow problems. Three-dimensional separation occurs, for example, when low aspect ratio devices such as submarines and torpedoes are operated at large angles of attack, α. Two low aspect ratio geometries, the DARPA Suboff bare hull geometry, which is a prototypical submarine shape, and a hemisphere-cylinder geometry were investigated. Numerical simulations and water tunnel experiments for the Suboff geometry for a Reynolds number based on diameter of Re= 10, 000 show little flow separation at α = 30°. A hemisphere-cylinder geometry was derived by replacing the Suboff forebody with a hemisphere. Simulations and water tunnel experiments were carried out for Re= 2000 and 5000. For α = 10° a large shedding separation bubble is observed on the leeward side. For α = 30° two counter-rotating leeward vortices appear and shedding is reduced. Proper orthogonal decomposition and Fourier analysis in time are employed for investigating the unsteady fluid dynamics. Conclusions are drawn with respect to the mean flow topology and possibly relevant hydrodynamic instabilities.
AB - The understanding of unsteady three-dimensional separation is lagging behind the understanding of two-dimensional separation due to its greater complexity and the limited amount of data for universal or canonical flow problems. Three-dimensional separation occurs, for example, when low aspect ratio devices such as submarines and torpedoes are operated at large angles of attack, α. Two low aspect ratio geometries, the DARPA Suboff bare hull geometry, which is a prototypical submarine shape, and a hemisphere-cylinder geometry were investigated. Numerical simulations and water tunnel experiments for the Suboff geometry for a Reynolds number based on diameter of Re= 10, 000 show little flow separation at α = 30°. A hemisphere-cylinder geometry was derived by replacing the Suboff forebody with a hemisphere. Simulations and water tunnel experiments were carried out for Re= 2000 and 5000. For α = 10° a large shedding separation bubble is observed on the leeward side. For α = 30° two counter-rotating leeward vortices appear and shedding is reduced. Proper orthogonal decomposition and Fourier analysis in time are employed for investigating the unsteady fluid dynamics. Conclusions are drawn with respect to the mean flow topology and possibly relevant hydrodynamic instabilities.
KW - Computational fluid dynamics
KW - Hydrodynamic instability
KW - Leeward vortices
KW - Three-dimensional separation
KW - Water tunnel experiments
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U2 - 10.1016/j.ijheatfluidflow.2013.04.016
DO - 10.1016/j.ijheatfluidflow.2013.04.016
M3 - Article
AN - SCOPUS:84888435728
SN - 0142-727X
VL - 44
SP - 53
EP - 70
JO - International Journal of Heat and Fluid Flow
JF - International Journal of Heat and Fluid Flow
ER -