Dear Anuj,
The wind field generated by TurbSim must encompass the entire rotor for the entire simulation, including any structural displacement that might occur, or else you will get errors about “Grid to small in …”. For a land-based wind turbine, I would typically set the grid size to be about 10% more than the rotor diameter in the horizontal and vertical directions. For a floating offshore wind turbine, I would set the grid size much larger. Please see the May 17, 2010 post in the forum topic linked here for an example TurbSim input file we’ve used for the NREL 5-MW baseline turbine: Updated NWTC Design Codes Available on Our Web Site.
Best regards,