[Chorkii]

Hi! I am working on my senior project on H2 combustion in ICE. I use Ansys Forte 2021 R1 Student to simulate the combustions by the use of H2 fuel. Right now, I am working on the tutorial given by Ansys itself. The name of the tutorial is Hydrogen Combustion. However, I encounter something that I cannot resolve and wish to ask for helps.
Right now, I am simulating my engine from IVC-EVO. I modify the set-up from the tutorial slightly (I change Chemistry mechanism). I find that it takes extremely large amount of time to process in each crank angle. I observe that the time constraint is always 'Fluxing Volume' in the Monitor Runs panel.
I find this situation kind of strange. The reason is that I tried to run the simulation with the this set-up before. During that time, I did not modify anything. It appeared that the simulation was pretty fast during IVC-EVO. However, the slow down happened, but happened approx. after 200 deg ATDC, which was the CA that I could ignore.
I do not know the reason for what I have mentioned, and the way to solve it. Your help is greatly appreciated!