Unsteady simulations of the flow around two cylinders arranged in tandem are carried out using Scale-Adaptive Simulation (SAS) turbulence model for high subcritical Reynolds number (Re = 2 × 10 5). Three-dimensional simulations are performed for different center-to-center distances between the cylinders (L/D varies 1.1 to 7, where D is cylinder diameter). The effects of the gaps between the cylinders are analyzed through the values of mean and fluctuating force coefficients, Strouhal number, pressure distribution, as well as through the wake flow structures behind both cylinders. The results are compared with published experimental data by different authors. The obtained results reveal good general agreement with the experimental data. Besides, to explore the effects of the interference, two tandem cylinders test are compared with a single cylinder case. The results show that this simple configuration (tandem) can strongly influence the flow pattern and forces on the cylinders. A critical nondimensional distance is obtained at L/D=3 at which two different flow patterns are identified, one pattern momentarily similar to the reattachment regime and another pattern similar to the co-shedding regime.

Numerical investigations using Scale-Adaptive Simulation (SAS) turbulence model are carried out to study the flow around a circular cylinder near to a plane boundary at Reynolds numbers between 8.6x10 4 and 2.77x10 5 with two different boundary layer thickness (δ) on the plane. The effects of gap (G) between the cylinder and the plane, the Reynolds number and the thickness of the plane boundary layer are analyzed through the drag and the lift coefficients, the Strouhal number, as well as through the wake flow structures behind the cylinder. Two and three-dimensional simulations are performed to examine the significance of the flow three-dimensionality when the cylinder is located near a plane. The SAS model results are compared with published experimental data and numerical results for similar flow conditions. The characteristics of the wake structures and force acting on the cylinder are in good agreement with previous studies. In general, the 3D-SAS model performed better than 2D-SAS. Based on the numerical results here obtained, the SAS turbulence model can be applied to study this flow configuration.

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