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Mass flow unsymetric matrix error
Posted Jun 21, 2013, 4:25 a.m. EDT Fluid & Heat, Computational Fluid Dynamics (CFD), Studies & Solvers Version 4.3a 1 Reply
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I am trying to do simulation of turbulent flow through a valve. I have a problem that the pressure variable seems to become unsymetric as soon as I have flow through the inlets of the valve.
I am able to have the water running through the valve from end to end, but as soon as I want i to flow in from the side without having flow from the end I get the following error
Failed to find a solution.
Segregated group 1
Singular matrix.
There are 87 void equations (empty rows in matrix) for the variable mod1.p.
at coordinates: (1219.24,80.7918,21.0936), (1218.72,81.0312,20.1543), (1220.41,81.0618,20.031), (1220.87,80.6622,21.5839), (1216.17,18.908,81.331), ...
There are 1 void equations (empty rows in matrix) for the variable mod1.spf.Pmfinl1.
at coordinates: (0,0,0), ...
Returned solution is not converged.
I have tried deleting the solver and restoring the default solver. Changing the dampening both up and down. Changing the mesh which gives more void equations with a finer mesh and less with a coarser. I have tried both itterative and direct solvers. And changing the mass fow rate up and down.
Can anyone see what I am missing here?
I am able to have the water running through the valve from end to end, but as soon as I want i to flow in from the side without having flow from the end I get the following error
Failed to find a solution.
Segregated group 1
Singular matrix.
There are 87 void equations (empty rows in matrix) for the variable mod1.p.
at coordinates: (1219.24,80.7918,21.0936), (1218.72,81.0312,20.1543), (1220.41,81.0618,20.031), (1220.87,80.6622,21.5839), (1216.17,18.908,81.331), ...
There are 1 void equations (empty rows in matrix) for the variable mod1.spf.Pmfinl1.
at coordinates: (0,0,0), ...
Returned solution is not converged.
I have tried deleting the solver and restoring the default solver. Changing the dampening both up and down. Changing the mesh which gives more void equations with a finer mesh and less with a coarser. I have tried both itterative and direct solvers. And changing the mass fow rate up and down.
Can anyone see what I am missing here?
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1 Reply Last Post Jul 2, 2013, 2:57 p.m. EDT
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Posted:
1 decade ago
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I do not know if you already solved your problem. Here is a solution I found. Change your inlet boundary condition from mass flow to velocity and give an average velocity as an input. I have attached a file with that BC and your model converges.
Sri.
I do not know if you already solved your problem. Here is a solution I found. Change your inlet boundary condition from mass flow to velocity and give an average velocity as an input. I have attached a file with that BC and your model converges.
Sri.
Attachments: