Computational Study of Vortex Shedding Behind Bluff Bodies
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A computational study of vortex shedding behind bluff bodies is presented. The main focus of this work is the study of vortex shedding and wake flow behaviour behind tapered circular cylinders in the laminar flow regime. However,a stepped circular cylinder in laminar flow as well as uniform circular cylinders in the turbulent flow regime have been investigated as well. In the laminar flow regime, the flow behaviour behind tapered and stepped circular cylinders is rather different than behind a uniform circular cylinder. Because the tapered and the stepped circular cylinders are three-dimensional objects, as opposed to uniform circular cylinder swhich are nominally two dimensional, secondary flows are generated along the cylinder span causing complex three-flow patterns which are stil not completely understood. The main motivation of the thesis is thus to contribute to improve knowledge of vortex shedding phenomena. This thesis is consists of two main parts. Firstly, a brief description of the work is given, as well as the numerical tools used, the vortex shedding phenomenon in laminar and turbulent flow regimes. In addition some of the results are presented. Secondly, the appendices in which published and submitted papers on the subject are enclosed. The aim of the first part is to provide details and/or questions which are not included in the later papers in order to form a more comprehensive document.
Has partsVallès, B; Andersson, HI; Jenssen, CB. Direct-mode interactions in the wake behind a stepped cylinder. Physics of Fluids. 14(4): 1548-1551, 2002.
Vallès, B; Andersson, HI; Jenssen, CB. Three-dimensional numerical simulation of laminar flow past a tapered circular cylinder. Parallel Computational Fluid Dynamics - Trends and Applications: 581-588, 2001.
Vallès, B; Andersson, HI; Jenssen, CB. Oblique vortex shredding behind tapered cylinders. Journal of Fluids and Structures. 16(4): 453-463, 2002.
Vallès, B; Andersson, HI; Jenssen, CB. Large-eddy simulation of turbulent flow past straight and tapered circular cylinders. Direct and Large-Eddy Simulation IV: 345-352, 2001.