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-   -   Bounds error for an EOS specified via an interpolation table (http://www.cfd-online.com/Forums/cfx/109188-bounds-error-eos-specified-via-interpolation-table.html)

cfdonlineuser November 11, 2012 22:07

Bounds error for an EOS specified via an interpolation table
 
I am having a problem solving a thermally driven convection problem where the fluid is liquid co2 is driven by thermal gradients in a deep vertical well. The problem solves quite well for constant properties but when the density is a variable function of pressure and temperature there is an error after the first time step. It's not time step size dependent. I use an interpolation user function for density in terms of pressure and temperature based on well known tables for liquid co2. The error is below. Obviously cfx thinks the derivative wrt pressure is invalid or too large. I've independently checked at the derivative and it's pretty linear. I've turned off buoyancy and the problem still persists

Any suggestions how to resolve this problem. Any way to interrogate this interpolation user function ie calculate the derivative wrt pressure ?

---------

*Fatal bounds error detected
*---------------------------
*Variable: Density Derivative wrt Pressure at Constant Temperature
*Locale *: CO2 WATER Domain

+--------------------------------------------------------------------+
| ERROR #001100279 has occurred in subroutine ErrAction. ************|
| Message: ************************************************** ********|
| Stopped in routine ENFORCE_BOUNDS *********************************

cfdonlineuser November 12, 2012 03:50

just an update to this thread, as I figured out what the problem was. I simply reordered the table so that pressure varies first then temperature in the table T,P,density.The error occurs when temperature varies first, which seems to me very arbitrary.


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