Computation of drag crisis of a circular cylinder using Hybrid RANS-LES and URANS models

Eswaran, Vinayak (2023) Computation of drag crisis of a circular cylinder using Hybrid RANS-LES and URANS models. Ocean Engineering, 270. p. 113645. ISSN 0029-8018

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Numerical simulation of flow past a circular cylinder across the “drag-crisis” region is extremely challenging for turbulence models because the boundary layer undergoes laminar–turbulent transition and variable-locus separation. We investigate the SA-DDES hybrid model along with two variants, namely, SA-kLES and SA-ILES, based on Spalart–Allmaras (SA) model, and include for comparison the SA-BCM transition and the SA-URANS models, for Re ranging from 50,000 to 5 million, using an in-house unstructured grid solver. All hybrid RANS-LES models produced clearly turbulent-like behavior, as evident from the Q-criterion, while the URANS models did not. A decline in the drag coefficient is noticed in all the turbulence models, but not the sharp decrease observed experimentally, with one exception: the SA-BCM transition model, which predicted the drag coefficients much closer to the experiments. The hybrid RANS-LES models outperformed the URANS SA-BCM model only in the fully turbulent trans-critical region and better represent the physics in the wake region for all Reynolds numbers studied. All the hybrid RANS-LES models produced similar results, suggesting comparatively equal performance in predicting separated flows. We believe that the performance of a hybrid model for mid-range Reynolds numbers will be greatly enhanced if the model is equipped to handle the laminar–turbulent transition.

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IITH Creators:
IITH CreatorsORCiD
Eswaran, VinayakUNSPECIFIED
Item Type: Article
Uncontrolled Keywords: Drag-crisis; Hybrid RANS-LES methods; SA-BCM transition model; Spalart–Allmaras model; Drag crisis; Hybrid model; Hybrid RANS-LES; Hybrid RANS-LES method; Laminar-turbulent transition; Reynold number; Spalart-Allmaras; Spalart-Allmaras model; Spalart–allmara-BCM transition model; Transition model; drag coefficient; large eddy simulation; modeling; Navier-Stokes equations; Reynolds number; turbulence; turbulent boundary layer; Atmospheric thermodynamics; Circular cylinders; Drag coefficient; Laminar boundary layer; Navier Stokes equations; Reynolds number; Turbulence models
Subjects: Physics > Mechanical and aerospace
Physics > Mechanical and aerospace > Transportation Science & Technology
Divisions: Department of Mechanical & Aerospace Engineering
Depositing User: Mr Nigam Prasad Bisoyi
Date Deposited: 22 Aug 2023 05:39
Last Modified: 22 Aug 2023 05:39
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