A mathematical model is developed to analyze the non-linear wave interactions (diffraction and radiation) with submerged body of arbitrary geometry in time domain using combination of high-order spectral method (HOSM) and boundary element method (BEM). In this method, HOSM used for the representation of free surface potential under kinematic and dynamic boundary conditions, and for body representation of the BEM is utilized. The current numerical model is validated with the previous study. Further, the present model is utilized to study the effect of various incident waves on free surface and also to study the vertical and horizontal drift forces on the submerged circular cylindrical-shaped body. The current numerical model can be implemented on practical applications to compute the forces and analyze the effect of it.