Résumé : Renewable energy usually refers to those natural resources of energy whose availability does not decrease with its usage. Various sources of renewable energy are there such as solar energy, wind energy, marine energy. The marine current turbine (MCT), is an exciting proposition for the extraction of tidal and marine current power. CFD simulation is being widely used in the research on marine current turbines. The present research also represents a step in this direction. Solution of incompressible unsteady Navier-Stokes (N-S) equations is required in the numerical simulation of flow around MCT. Large eddy simulation (LES) has been opted which fully resolves the energetic turbulent flow structures and models only the sub-grid scale turbulence. IB method has been used to enforce the boundary conditions on complex geometry. Due to computational limitations we have been able to perform only a coarse grid LES of the marine turbine for specific operating conditions. Nevertheless, the results provide insights into the flow structures around the marine turbine. Analysis shows that the effect of vorticity diminishes after 11R from the turbine rotor blade. However, the velocity deficit region remains until the end of the domain used in our simulations which is 10D distance downstream of the rotor blades.