Fluid-structure interactions (FSI) arise in a wide-ranging engineering application such as electric, mechanical, and biological systems. Examinations of lighter and flexible objects entails a rapid development in experiments and new simulation models that fully illustrate the mutual interaction of flexible bodies and fluid [1]. Our research work presents a numerical approach to examine FSI on a single flexible flap submerged in an open water channel. The proposed method is specifically applied to investigate flow conditions of Reynolds number, Re, 700 < Re < 7000 [2]. The two-way coupled FSI method is employed to simulate the flap and flow behaviors and are compared with PIV measurements. Transient simulations are performed using the commercial ANSYS Workbench. To pursue the FSI simulations based on experimental conditions, both finite element (FE) analysis and computational fluid dynamics (CFD) models are independently designed. Model, mesh, boundary conditions and solvers are defined individually for solid and fluid. The geometry of the whole field is modeled in the ANSYS -Design Modeler and therefore defining a rectangular flow domain representing the unsteady flow and the corresponding immersed body-flap is supposed to be mounted on the plate and engrossed in the fluid (see Figure 1). Afterwards a two-way FSI coupling is introduced between the individual domains by means of ANSYS-System Coupling. Both numerical and experimental data signify the mutual interaction of flexible flap and fluid, also the flap experiences both the stream-wise and span-wise deformations [3]. The stream-wise bending is perceived from the numerical data and is in agreement with the experimental results (see Figure 2). Similarly, the flow and flap frequencies are also compared with measurements. Moreover, the drag coefficient is computed for a wide range of Reynolds number indicating reduction in drag induced by the flap bending. A minimum value of 1.18 is achieved at highest Re, indicating a 30 % decrease in comparison to the rigid flap. Present results could be helpful in designing thin flexible structures for engineering and natural science applications.