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Initial Values Consistency Problem
Posted 03.06.2020, 09:17 GMT-4 Fluid & Heat, Computational Fluid Dynamics (CFD), Microfluidics Version 5.5 1 Reply
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Hello
I am modelling the injection of single-phase flow in a container of multiphase fluid (reservoir).
When I run my model with a defined inlet pressure BC, it runs probably without any need to define an outlet BC (at the reservoir boundary).
But in my model, I am interested in modelling the constant inlet mass (constant inlet velocity) through a channel into the reservoir to explore the pressure development at the reservoir boundary (wall). When I do so (defining an inlet velocity), it gave am the following error (Failed to find consistent initial values. Last time step is not converged.)
It required me to define an outlet pressure or a pressure point constraint which is not the purpose of my study (I need the reservor boundary to be defined as a wall).
I already tried defining a step function to smooth the inlet velocity, but it doesn't work.
Cheers, Rami
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Hello Rami,
The fact of the matter is that pressure enters the Navier Stokes equations only through its derivatives. As a result, unless you specify the pressure somewhere in your model, there isn't a unique solution to the mathematical problem you're asking COMSOL to solve.
For more details, read for instance this thread.
Best regards,
Jeff
-------------------Jeff Hiller