Can you please elaborate perhaps by sharing some illustrations?

Effect of mesh on HTC can be understand through grid independence test.

It is a difficult process to choose a mesh for the CFD computations. A mesh that is too
coarse will result in large errors; an overly fine mesh will be costly in computing time. To
demonstrate the impact of the mesh size on the calculation results, any CFD simulation should be
accompanied by a grid sensitivity analysis.

For the purposes of the grid sensitivity analysis, the convective heat transfer coefficients (HTC) should be calculated and compared for different grid densities.

Thank you