How to check for grid independance in FLUENT. mine is a steady state case of natural convection in vertical tube. Ravi

I think you ought to run the simulation on different, increasingly refined grids and evaluate the change in important parameters such as pressure and velocity

Just an addition here. You may want to do plots of the some parameters, such as shear stress, temperature distribution, velocity distribution and save them for each mesh size. Then compare them. Also look at comparing the fRe values and also compare them to literature data if you have any.