There are two main concerns in a numerical simulation: computational cost and the accuracy of simulation. In order to know whether a simulation is accurate or not, you need to match your simulations with experiment results. Hex mesh gives a faster computation and a better mesh quality (in most cases) but still you need to match your simulation results to experiment results. Also, grid independence test is an important step in optimizing the simulations.

@ Amit, thanks for the update.

I am talking about the type of mesh, and the corresponding accuracy it provides.

@ Ernest, thanks for the update.

I fully agree with you, but again i am trying to understand the advantages and disadvantages of hex and poly mesh. A comparison between them.

Dear Rajesh,

If ur geometry is symmetrical, hexahedral is suitable and will yield best results. If it is not then u have to go for polyhedral. Again there are different meshing options to get better quality mesh in case of unsymmetrical objects. But note that the meshing should be conformal.