[Mmn11]

I'm using Ansys 2020 R1 and my PC has intel core i5 8th gen processor. It has 4cores and the base speed is 1.8GHz. When I run simulations in fluent I usually run parallel processing with 3 cores. My PC has 16GB ram. While a simulation runs the CPU usage is consistent at around 90% and RAM usage is 90-97%.

However, last few days my CPU usage is fluctuating around 30-60%, and a simulation which took 3 hours to complete previously is now requiring 15-15 hours. The ram usage is still consistent around 90%. Did any of you face similar issues? If so, please help!

I will be grateful for any suggestions. Cheers!

[flotus1]

Sounds a lot like you are running out of physical memory.
Don't trust the memory total usage reported by Windows task manager. Your PC will start swapping (using disk space instead of memory) long before task manager reports 100% memory usage.
That would be in line with you seeing reduced CPU usage now. The data just can't be shoveled fast enough towards the CPU to keep the cores busy. And the fact that your simulations now take 5 times longer. And of course you already saw memory usage close to 100%

tl;dr: install more memory or reduce the cell count of your simulations
Or try to find other running programs that use a significant amount of memory and close them

[Brad93]

Hello,

I have a small question, how do I know if I can close a running program that uses a large amount of memory. I am always a little afraid that closing them will cause problems with the operation of my PC.

[wkernkamp]

Only if it is an operating system related component. Otherwise, you can close anything without a problem. (Except for unsaved info)