Aerodynamic performances and wake topology past a square cylinder in the interface of two different-velocity streams

Autor: Fernando Mellibovsky, Reda Mohamed Yousif Abdallah El Mansy, Wasim Sarwar, Josep M Bergada i Granyo
Přispěvatelé: Universitat Politècnica de Catalunya. Departament de Mecànica de Fluids, Universitat Politècnica de Catalunya. Departament de Física, Universitat Politècnica de Catalunya. MICROTECH LAB - Microtechnology for the Industry, Universitat Politècnica de Catalunya. DF - Dinàmica de Fluids: formació d'estructures i aplicacions geofísiques
Rok vydání: 2022
Předmět:
Zdroj: UPCommons. Portal del coneixement obert de la UPC
Universitat Politècnica de Catalunya (UPC)
ISSN: 1089-7666
1070-6631
2016-7784
DOI: 10.1063/5.0090602
Popis: We analyze the incompressible flow past a square cylinder immersed in the wake of an upstream splitter plate, which separates two streams of different velocities, UT (top) and UB (bottom). The Reynolds number associated with the flow below the plate is kept constant at ¿¿¿=¿¿¿/¿=56, based on the square cylinder side D as characteristic length. The top-to-bottom flow dissymmetry is measured by the ratio ¿=¿¿¿/¿¿¿¿[1,5.3] between the Reynolds numbers above and below the plate. The equivalent bulk Reynolds taken as the mean between top and bottom changes with R in the range ¿¿=(¿¿¿+¿¿¿)/2¿[56,178]. A Hopf bifurcation occurs at ¿=2.1±0.1 (¿¿=86.8±2.8), which results in an asymmetric Kármán vortex street with vortices only showing on the high-velocity side of the wake. A spanwise modulational instability is responsible for the three-dimensionalization of the flow at ¿¿3.1 (¿¿¿115) with the associated wavelength of ¿¿¿2.4. For velocity ratios ¿=4, the flow becomes spatiotemporally chaotic. The migration of the mean stagnation and base pressure points on the front and rear surfaces of the cylinder as R is increased determine the boundary layer properties on the top and bottom surfaces and, with them, the shear layers that roll up into the formation of Kármán vortices, which in turn help to clarify the evolution of the lift and drag coefficients. The symmetries of the different solutions across the flow transition regime are imprinted on the top and bottom boundary layers and can, therefore, be analyzed from the time evolution and spanwise distribution of trailing edge boundary layer displacement thickness at the top and bottom rear corners This work was supported by the Spanish Government under Grant Nos. FIS2016-77849-R and PID2020-114043GB-I00 and by the Catalan Government under Grant No. 2017-SGR-00785. Part of the computations were done in the Red Española de Supercomputación (RES), Spanish supercomputing network, under Grant Nos. FI-2019-1-0023 and FI-2018-3-0030. F. Mellibovsky is a Serra-Húnter fellow
Databáze: OpenAIRE
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