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Numerical simulation of the 3D flow around a circular cylinder using algebraic non-linear Reynolds stress models

Grant number: 05/03050-2
Support type:Regular Research Grants
Duration: December 01, 2005 - February 29, 2008
Field of knowledge:Engineering - Naval and Oceanic Engineering
Principal researcher:Fábio Saltara
Grantee:Fábio Saltara
Home Institution: Escola Politécnica (EP). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

The numerical simulation of the flow around circular cylinders is a main topic of the design of offshore structures. An example of the importance of this subject is the project and life span evaluation of oil risers. These circular cross-section structures are subjected to flows with a Reynolds number range between 10000 and 1000000. In this case, the wake flow is characterized by vortex shedding and by the existence of turbulent three-dimensional structures. Nowadays, the tendence is to simulate this phenomenon through Large Eddy Simulation (LES). One of the main reasons is that is very easy to program the smagorinsky model in existing laminar Navier-Stokes codes. Nevertheless, LES has a major drawback: although is produces good results for 3D flows, the technique needs very fine meshes and small time-steps, requiring expensive hardware. Traditional techniques like Reynolds Averaged Navier Stokes models (RANS) are atracting less attention than LES. THis can be explained through the need to program the solution of transport equations for the turbulent kinetic energy and its dissipation length. Moreover, RANS is based in the Boussinnesq hypothesis, in which we have a linear relation between the Reynolds stress and deformation tensors. As a result, models based in the Boussinesq hypothesis cannot correctly describe the Reynolds stress anisotropy, producing resulats for 3D flows that do not agree with the experimental measurements. Nevertheless, RANS models have a main advantage over LES: they require coarser meshes and do not need very small time steps, resulting in less expensive simulations. To use RANS for 3D simulations of the unsteady flow around bluff bodies, it is needed to develop non linear models to for the Reynolds stresses. So, the main goal of this project is to develop a FORTRAN code that can solve unsteady three dimensional flows around bluff bodies using RANS models coupled with algebraic non-linear models for the Reynolds stresses. (AU)

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Scientific publications
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
SALTARA, F.; D'AGOSTINI NETO, A.; LOPEZ, J. I. H.. 3D CFD Simulation of Vortex-induced Vibration of Cylinder. INTERNATIONAL JOURNAL OF OFFSHORE AND POLAR ENGINEERING, v. 21, n. 3, p. 192-197, . (05/03050-2)

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