In the present numerical study, a Fluid-Structure Interaction (FSI) modeling of a thin flexible splitter plate attached to the back of a rigid horizontal circular cylinder is carried out via using COMSOL Multiphysics 5.6 which is based on the Finite Element Method (FEM). The cylinder and its oscillating splitter plate is placed in a two-dimensional, laminar, incompressible, viscous, and horizontal channel flow. Both governing equations of the solid and fluid are solved in an unstructured triangular mesh. An Arbitrary Lagrangian-Eulerian (ALE) formulation is applied to consolidate the geometrical changes of the fluid domain. After validating the simulations via comparing the results with the data available in the literature, the effects of the length and thickness of the splitter plate on the flow characteristics are investigated. It was found that both the length and the thickness of the splitter plate affect the formation, development, and shedding of the vortices behind the cylinder, as well as the pressure difference between the end of the splitter plate and the front stagnation point of the cylinder.
