HELP ( 3D airfoil computation)

shan

want to analyse flow around 3Dimensional airfoil blade( wind turbine) so as to calculate coefficient of lift n drag.I have done for 2 D airfoil but have no clue how to make 3D airfoil computation.Somewhere it was written to make one blade and for rest of the two blades use periodic boundary conditions for it.can anyone tell whats this periodic boundary is it.Please tell me how to proceed for three dimensional and what boundary conditions to put for also do I need fan model or moving mesh or do i simply need to make a three dimensional stationary airfoil blade and simulate it for flow passing it....please help me...