Abstract
A random flow generation (RFG) algorithm for a previously established large eddy simulation (LES) code is successfully incorporated into a finite element fluid flow solver to generate the required inflow/initial turbulence boundary conditions for the LES computations of viscous incompressible turbulent flow over a nominally twodimensional circular cylinder at Reynolds number of 140,000. The effect of generated turbulent inflow boundary conditions on the near wake flow and the shear layer and on the prediction of integral flow parameters is studied based on long time average results. No-slip velocity boundary function is used but wall effects are taken into consideration with a near wall modelling methodology based on van Driest Damping approach. The numerical results obtained from simulations are compared with each other and with the experimental data for different turbulent inflow boundary conditions to assess the functionality of the RFG algorithm for the present LES code and hence its influence on the vortex shedding mechanism and the resulting flow field predictions.
Highlights
The turbulent flow field around a circular cylinder is a great practical importance for many engineering applications such as hydrodynamic loading on ocean marine piles and risers, bridges
The numerical simulations are performed in conjunction with the random flow generation (RFG) algorithm for different turbulent inflow boundary conditions i.e. varying degree of turbulence at a Reynolds number of 140,000
The following conclusions can be withdrawn from the present study: 1) The turbulent inflow data generated by the proposed RFG algorithm improves the flow resolution in the near wake and the predictions for the integral parameters
Summary
The turbulent flow field around a circular cylinder is a great practical importance for many engineering applications such as hydrodynamic loading on ocean marine piles and risers, bridges. One is to conduct the auxiliary simulations of turbulent flow fields using LES approach [3] and to store the time series of fluctuating velocity components for inflow boundary conditions of the main simulations. In this approach, the velocity field extracted from a plane near the domain exit is basically rescaled and is reintroduced as a boundary condition at the inlet. The velocity field extracted from a plane near the domain exit is basically rescaled and is reintroduced as a boundary condition at the inlet This approach will not be applicable to cases where scale laws are non-trivial.
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