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Locating and observing a transient fluid phenomena

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Old   September 23, 2011, 13:47
Default Locating and observing a transient fluid phenomena
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Hi,

I am simulating a single phase fluid flow. I am having some difficulties in getting convergence with steady state assumption for fluid flow. After extensive discussion with and guidance from Glen, I am now simulating my flow with transient assumption.
I want to locate where, in my flow domain, is any transient fluid flow phenomena located. I want to locate it and observe , say velocity and fluid pressure in that phenomena as simulation progress in time. Basically, I want to see how much the fluid velocity/ pressure etc. fluctuate in time at such locations.

I know that I can generate monitor points and output fluid flow variables on those points and then observe them in solver manager. But I don't know where I should place these monitor points.

So if there is a better and more systematic & efficient way to approach this , it will be very helpful.
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Old   September 24, 2011, 06:29
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Ideally you would like to view the velocity or pressure gradient WRT time. Not sure how you can do this. I would just view some animations of velocity and/or pressure field and you should be able to find it.

Alternately you could look at the steady state runs in the post processor and view the residuals variable. The region of high residuals will be the unstable region.

But the transient bit is almost certainly after a bluff body, separation or jet. That would count for most of these instabilities in general use.
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Old   September 25, 2011, 18:49
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Thanks Glen. I am now monitoring velocity and pressure by inserting some monitor points in areas of high residuals from steady state runs.
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