[Daniel_Khazaei]

Hello to all,

I have just started to use CFD-Post to post-process simulation's results from Ansys Fluent. I have a question about time integration in CFD-Post.

Is it possible to perform time integration in CFD-Post?


Regards

[ghorrocks]

What type of time integration? What do you want to integrate?

I usually export that sort of data from CFX and do time integrations in a mathematical application like matlab/python/excel.

[Daniel_Khazaei]

Originally Posted by ghorrocks

What type of time integration? What do you want to integrate?

I usually export that sort of data from CFX and do time integrations in a mathematical application like matlab/python/excel.

Well I want to calculate the oscillatory shear index (OSI) according to the following equation:



To do so, I need to integrate wall shear stress over time! Is there anyway to do the integration directly in the CFD-Post?

best wishes

[ghorrocks]

This is far better done in the solver. This is because you then can use every time step for the time integration, whereas in the post processor you can only use the time steps you have results files for.

So I would recommend you rerun the simulation with a monitor point outputting the wall shear stress at the point (or averaged or whatever) you want. Then you can easily do the equation you describe in a mathematical package.

If it is not possible to rerun the simulation then all you can do is export the wall shear stress for the time steps you have data for. Then you again do the time integration in a mathematical package. This is far less accurate as you will not have as good time resolution.

[Daniel_Khazaei]

Originally Posted by ghorrocks

This is far better done in the solver. This is because you then can use every time step for the time integration, whereas in the post processor you can only use the time steps you have results files for.

So I would recommend you rerun the simulation with a monitor point outputting the wall shear stress at the point (or averaged or whatever) you want. Then you can easily do the equation you describe in a mathematical package.

If it is not possible to rerun the simulation then all you can do is export the wall shear stress for the time steps you have data for. Then you again do the time integration in a mathematical package. This is far less accurate as you will not have as good time resolution.

I can only go for the second option as it will take months to rerun the simulations as I don't have enough time and resources!

So, I have to extract the shear stress for every single case and data manually and do the integration with another software?

[ghorrocks]

You should have planned a bit better before the simulations started then

Yes, extract the data from CFD-Post and export it somewhere. You can use the CFD-Post session files or other scripting capabilities to make this easier. Then do the time integration in a another software.