Ansys Fluent – Performance Degredation

[mmitch48]

Good afternoon,

I'm working with someone who is running Ansys Fluent and is running into some issues. They had reached out to me for support but this is out of my realm of expertise, as I don't use Ansys myself. The user reached out because they thought that the computer might be overheating and throttling the CPU. 

The scenario: the user has been running cases without any issues up until recently. Now when they set up a case to run, it's take maybe 2 or 3, maybe 4 times as long to complete.

What they're noticing is that Ansys Fluent seems to run ok at the start, but over time, slows down. They thought that the computer might be overheating and throtting the CPU performance. We're monitoring the CPU temperatures with a couple different applications and they don't seem to indicate that CPU throttling was occurring.

We've been monitoring the CPU performace in the Task Manager, and are seeing dips in CPU utilization. These dips become deeper, and longer, over time.

I have some screenshots below that hopefully showcases what we're seeing. If there are specific questions that need answered, or other pieces of information you need to help us indentify this, please let me know.

This screenshot shows CPU utilization maybe an hour or 2 after starting the case:

After a few more hours:

After many hours (left over night):

I forgot to add - we're running Ansys 2023 R2.

The processor is included in the screenshots.

Thanks!