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-   -   Measuring Pressure in Unsteady problems in specific time step (http://www.cfd-online.com/Forums/star-ccm/106344-measuring-pressure-unsteady-problems-specific-time-step.html)

Milad August 26, 2012 20:44

Measuring Pressure in Unsteady problems in specific time step
 
Hi,

I am doing an unsteady case with Star-ccm+. I have done 300,000 iterations. but now I need to know the pressure in some specific time steps. My question is how I can measure pressure distribution in the previous time steps while I have not define any probe before.

siara817 August 27, 2012 04:51

I do not think if you can do that. Just to say that it is nice for next time to use autosave located in the File, to save after every specific time step.
A question: Why do you use transient, why not steady state?
Good luck

Milad August 27, 2012 07:57

Many thanks for your answer; I am analysing A pitching airfoil problem so that I need to use unsteady solver.

Any way, It is a very bad news for me that it is not possible to go back to specific time step.

ryancoe August 27, 2012 09:31

In the newer versions of Star-CCM+, there's a feature called 'Solution Histories' which allows you to do this sort of thing, but it must be set to record the data you're interested in before you begin iterating the solution.

Ryan

abdul099 August 28, 2012 18:57

And history files can get huge very quickly when you snapshot too often.

By the way, the amount of data is the reason why you can't access the pressure data afterwards, since it's not stored. A simple, nice 10 million trimmed cells mesh sim-file needs about 4GB space on the hard disk. About half of the space is needed for the solution, the other half for the mesh (just a rough number, depending on physics etc.). Now imagine, you'd run for several thousand time steps and save all the data every time step, to give a user the option to think about postprocessing after solving instead of thinking before.
Please let me know when you're planning to do this and I will open shop selling hard disks - and get my Corvette pretty quick!


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