time needed to run a a simulation
 

i am simulating internal and external air flow inside a building using ansys flotran. i have a total element number of 2.5 million elements and the file is 19 GB. it took me 12 hours to run 100 iterations... is this normal????? please advise me since i am afraid that something might be wrong with my simulations or set up!

run the simulations using more cores? My guess is you are using only one core for the calculations.

what do you mean by more cores?

There is really not enough information to answer the initial question. Without knowing the hardware you ran the simulation on it is impossible to comment on the simulation time.
It might be normal on an old laptop or a machine with too little memory. It might be slow on a modern workstation.