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UDF profile based on function of flow time ERROR!

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Old   September 1, 2016, 18:39
Default UDF profile based on function of flow time ERROR!
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Ash Kotwal
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I'm running 2 phase flow implicit Eularian-Eularian flow model.
created model.

defined material to each phase.

defined boundary conditions-for inlet, it's mass flow rate with initial gauge pressure defined

defined outlet pressure boundary condition- as outlet pressure values.

Then velocity slip ratio defined based on variable mass flow rate of phase 1 but constant mass flow rate of phase 2.

All above boundary conditions are defined as profile UDFs as function of flow time.

then phase coupled simple solver is used.

rest is just a calculations activities, with surface monitors.

the case successfully setup and started calculations till 300 time steps with 1 second as time step size.

after that UDF, as function of time, provides new values to the solver. and that's where everything goes wrong and suddenly I receive divergence in AMG solver. Which I shouldn't be getting since the case ran successfully for first 300 time steps

so I need help to know what exactly went wrong.

thank you,

regards,
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Old   September 2, 2016, 09:35
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Bruno Machado
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Quote:
Originally Posted by Ash Kot View Post
I'm running 2 phase flow implicit Eularian-Eularian flow model.
created model.

defined material to each phase.

defined boundary conditions-for inlet, it's mass flow rate with initial gauge pressure defined

defined outlet pressure boundary condition- as outlet pressure values.

Then velocity slip ratio defined based on variable mass flow rate of phase 1 but constant mass flow rate of phase 2.

All above boundary conditions are defined as profile UDFs as function of flow time.

then phase coupled simple solver is used.

rest is just a calculations activities, with surface monitors.

the case successfully setup and started calculations till 300 time steps with 1 second as time step size.

after that UDF, as function of time, provides new values to the solver. and that's where everything goes wrong and suddenly I receive divergence in AMG solver. Which I shouldn't be getting since the case ran successfully for first 300 time steps

so I need help to know what exactly went wrong.

thank you,

regards,
We have no idea about your code or if something else in your configuration is wrong. Maybe the time step you are using is too big, maybe is under relaxation factor, maybe is something else. with the information you provide, i dont think any one can help you.
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