TY - GEN

T1 - Fully-resolved LES of weakly separated flows

AU - Chang, Peter A.

AU - Vargas, Abel

AU - Jiang, Minyee

AU - Lummer, Dory

AU - Mahesh, Krishnan

PY - 2011

Y1 - 2011

N2 - A high-accuracy large eddy simulation (LES) is applied to flows over a sphere and an underwater vehicle. Both objects have relatively weak separated stern flows that may depend upon the accurate resolution of turbulence structures in the attached flow regions upstream of the separation point. For the sphere we compute flows over a range of Reynolds numbers from sub- to super-critical (Re = 1×104 to Re = 1:14×106, respectively) for which we obtain decent agreement for the separation location, pressure distributions and integrated forces. Long time series data shows evidence of low-frequency shedding phenomena. We perform LES on the Advanced SEAL Delivery System (ASDS), an underwater vehicle with a rounded-rectangular cross section and stern slope that promotes weak flow separations. We compute the fully resolved flow over the ASDS for length-based Reynolds numbers 128 × 103, 256 × 103 and 512 × 103. We show that the mean flow fields over the attached flow region are reasonable in that the boundary layer profiles, shape factors and skin friction agree with other examples of developing turbulent boundary layer flows. The instantaneous flow fields exhibit near-wall turbulence structures with the correct length scales and dynamics as compared with the wall-bounded turbulent flow literature. The separation point moves aft and the extent of the separation region decreases markedly as the Reynolds number increases.

AB - A high-accuracy large eddy simulation (LES) is applied to flows over a sphere and an underwater vehicle. Both objects have relatively weak separated stern flows that may depend upon the accurate resolution of turbulence structures in the attached flow regions upstream of the separation point. For the sphere we compute flows over a range of Reynolds numbers from sub- to super-critical (Re = 1×104 to Re = 1:14×106, respectively) for which we obtain decent agreement for the separation location, pressure distributions and integrated forces. Long time series data shows evidence of low-frequency shedding phenomena. We perform LES on the Advanced SEAL Delivery System (ASDS), an underwater vehicle with a rounded-rectangular cross section and stern slope that promotes weak flow separations. We compute the fully resolved flow over the ASDS for length-based Reynolds numbers 128 × 103, 256 × 103 and 512 × 103. We show that the mean flow fields over the attached flow region are reasonable in that the boundary layer profiles, shape factors and skin friction agree with other examples of developing turbulent boundary layer flows. The instantaneous flow fields exhibit near-wall turbulence structures with the correct length scales and dynamics as compared with the wall-bounded turbulent flow literature. The separation point moves aft and the extent of the separation region decreases markedly as the Reynolds number increases.

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M3 - Conference contribution

AN - SCOPUS:84880620027

SN - 9781624101489

T3 - 20th AIAA Computational Fluid Dynamics Conference 2011

BT - 20th AIAA Computational Fluid Dynamics Conference 2011

T2 - 20th AIAA Computational Fluid Dynamics Conference 2011

Y2 - 27 June 2011 through 30 June 2011

ER -