Numerical investigation of low Reynolds number flow past two and three circular cylinders using unstructured grid CFR scheme

An incompressible unsteady viscous two-dimensional finite volume Navier-Stokes solver is developed using 'consistent flux reconstruction' technique on a collocated unstructured mesh comprising of triangular cells. In this solver, the full Navier-Stokes equations have been solved numerically in the physical plane itself without using any transformation to the computational plane. The cell face centre velocities are reconstructed explicitly by solving the momentum equations on flux reconstruction control volumes defined judiciously around the respective cell face centres. This is followed by solution of the cell centre pressure field using a discrete Poisson equation developed from the reconstructed velocities and updating the cell centre velocities by using an explicit scheme. In the present investigation, the solver has been applied to unconfined flow past a single cylinder, two cylinders and three cylinders for Reynolds number (Re) = 100 and 200. To validate the numerical code the present results for single and two cylinder arrangements were compared with results available from literature and found to be agreeing well. For the two and three cylinder configurations flow has been computed for various gaps between cylinders and for both side-by-side and tandem arrangements. Different wake patterns like in-phase and anti-phase synchronized wake patterns, flip-flopping, deflected wake patterns and steady wake patterns are observed depending on the Reynolds number and the gap spacing.