The closure dynamics of an artificial aortic heart valve for single leaflet is investigated numerically during diastolic phase of flow. A two-dimensional fluid-structure interaction model is presented and simulated using an immersed boundary method adopting arbitrary Lagrangian-Eulerian algorithm. The present modeling is based on an efficient Navier-Stokes solver accepting the fractional step method and Cartesian grid system to solve incompressible fluid flow in an Eulerian domain. A moving Lagrangian grid is used to descritized the structure domain and the equation of structure motion is derived by the energy method. I have validated our numerical method with experimental data for leaflet positions and axial velocity profile at successive time points and it shows very good agreement between numerical and experimental results. Simulation results have been analyzed mainly by considering the leaflet length, bending rigidity of the leaflet and different sinus shapes for better valve closure. The investigations and analysis suggests that the valve-leaflet closes most effectively for the leaflet length (L) =26 mm, bending rigidity (EI) = 4.61 $N-mm^2$ and full sinus at fluid flow of 60 bps (1 Hz).