Hie KeyurnYes I used design modeller to create the domains (Non-rotating domain created by subtracting the rotating smaller domain to create a rotating void in the non rotating domain. For the rotating domain I subtracted the blade geometry from SolidWorks from the non rotating smaller domain to create a blade void)nI managed to mesh the non-rotating but this problem is on the rotating domain with a blade void nI checked the geometry in SpaceClaim and it has no errors. I proceeded to meshing and selected CFD as physics preference. For the other options you suggested kindly confirm the followingn3..Confirm by body/face/edge sizing you mean I should specify element size for meshing the geometry? Also my geometry is 6.55 m long and 1 m thick. The blade void inside is 6 m long with and very thin . What element size do you suggest I use?n4..The error is being picked on one surface of the blade. Is there any way to rectify the problem without redesigning the blade because it?s drawn from standard airfoil coordinates and changing it will affect my simulation resultsn5 Periodicity is correctly defined nRegards nLovelord