A two-dimensional Large Eddy Simulation (LES) is conducted for triangular rod ahead of a square cylinder at Reynolds Number, Re = 90,000. Vortex shedding is captured when two objects are kept at varying distance with different sizes of the upstream rod, the case under consideration are decided on the basis of the mode of flow (the cavity flow mode and the wake impingement mode) for d/D = 0.2 and 0.6 with L/D lying in various modes of flow. It is observed that the vortex shedding in cavity flow mode is much affected by the upstream rod such that the vortex shedding sometimes in very slightly affected by the shedding from the rear cylinder; whereas in wake impingement mode, the shedding is affected by both the objects. Hence, a superimposition of both the fluctuations is found behind the cylinder.

Keywords: Large Eddy Simulation (LES), Cavity Flow Mode (CFM), Wake Impingement Mode (WIM), Vortex shedding.