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-   -   Reference Pressure with RGP table - Out of Bounds message even though it isn't? (https://www.cfd-online.com/Forums/cfx/187265-reference-pressure-rgp-table-out-bounds-message-even-though-isnt.html)

evcelica May 2, 2017 17:56

Reference Pressure with RGP table - Out of Bounds message even though it isn't?
 
I'm using an RGP table that goes from 15 psia to 75 psia. My minimum pressure in my simulation is ~33 psi, max is 55 psia. Yet I'm getting an out of bounds error for absolute pressure. Does this have anything to do with my reference pressure? I set it for the outlet pressure of 33 psi Why would it tell me out of bounds when it isn't? Everything looks to make sense in the results as far as I can tell.

Here is what the table bounds errors look like:

+--------------------------------------------------------------------+
| |
| Independent variables went out of bounds while computing the |
| variables listed below using table interpolation. In each case |
| the bounds error was handled by clipping or extrapolation. |
| If this situation persists, consider increasing the table range. |
| |
+--------------------------------------------------------------------+
| |
| Location Name : LXe Domain |
| Mesh location : VERTICES |
| Routine : Post_soln |
| Partition : 10 |
| Variable Name : Density |
| Ind. Variable : Absolute Pressure |
| Bound : Lower |
| Min Value : 2.2708E+05 |
| Handled By : Clipping |
| |
+--------------------------------------------------------------------+
| |
| Location Name : LXe Domain |
| Mesh location : VERTICES |
| Routine : Post_soln |
| Partition : 10 |
| Variable Name : Total Temperature |
| Ind. Variable : Total Pressure |
| Bound : Lower |
| Min Value : 2.2708E+05 |
| Handled By : Clipping |
| |
+--------------------------------------------------------------------+


Long List of these. All saying independent variable is absolute pressure or total pressure.

ghorrocks May 2, 2017 18:40

Do you get bonds error when you use a simple material model (eg ideal gas?).

It should not have anything to do with the reference pressure, but if the reference pressure is poorly set it might contribute to numerical instability which leads to things like bounds errors.

Are you sure these bounds errors are not physical?

evcelica May 2, 2017 21:13

I didn't get a bounds error when I was running Liquid Xenon. But now with gaseous Xenon and an RGP table I get these bounds errors. 2.2708E+5 Pa is ~33 psia, which is about my outlet pressure, and that makes sense. My RGP table goes down to 15 psia, but it is acting is if my table stops somewhere above 33 psia, since it is giving me these warning messages.
I'll have to try to look at my rgp table and make sure it goes down to 15 psia, but it is 75 MB of text.....sigh.
I'll probably just make a new one with a larger range and see if I still get the error.


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