Problem with doing natural convection in cylinder
 

Hi guys, i am currently undertaking a project that requires me to simulate natural convection of a fluid in a 3-d cylinder heated from bottom to top. However although i have managed to create a cylinder i have no idea if the meshing i have done is correct.

All i have done is used mapped face meshing on the top, bottom and wall of the cylinder, in addition to adjusting the sizing. Is that enough?

Also when i run my calculations in fluent it takes extremely long just to converge. Is that normal?? I am pretty sure that there is a problem somewhere because whenever i try to check the surface nusselt number it comes out as a weird number.

Please if anybody would know where to get a similar tutorial to this question do help me. It's been fustrating me for quite awhile now.