Dear Ibtihaj Faridi, I might not get you right...however are you trying to say that as the zone of meshing changes (over the casting period), so you need some kind of time dependent mesh? If that is the case, I would suggest you to follow birth and death approach, You might refer to the following page for this purpose:http://www.mece.ualberta.ca/tutorials/ansys/AT/BirthDeath/BirthDeath.html

If that is not the case, I would request you to kindly elaborate the proble,

Best of luck.

Yes, the solution refers to the element birth and death feature in APDL.

Thanks for your suggestion, but actually i have already seen the above tutorial but in that the killing of element depends on temperature. What i need to do is to get a certain thickness after each timestep. I want to activate elements with time not by some material property like temperature etc.