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Old   February 14, 2013, 06:57
Default sprayFoam flow and mixture formation
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André Zboralski
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Hallo everyone,

I tried to calculate a case with inlet flow in a cyinder and injection (constant mesh, no piston moving). Therefore I used sprayFoam. I forced a velocity at the outlet and the inlet is zero gradient. At first the result looked really good, but later the iteration became very small because the velocity in one cell at the inlet surface rose to 800 m/s. I tried to run diffrent cases --> but always the same. I thought it could be a mesh problem, so I did checkMesh --> Mesh OK

can anybody help me!
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Old   February 14, 2013, 07:45
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Robert
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Hey,

how does the temperature in your domain behave before the time step decrease occurs? I've encountered severe problems with temperature divergence, pressure divergence, very high velocities and thus very small time steps followed by a crash of the simulation - I fixed this by deactivating time step adjustment and setting a fixed timestep.

Best regards,

Robert
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Old   February 14, 2013, 10:25
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André Zboralski
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>>Hey,

how does the temperature in your domain behave before the time step decrease occurs? I've encountered severe problems with temperature divergence, pressure divergence, very high velocities and thus very small time steps followed by a crash of the simulation - I fixed this by deactivating time step adjustment and setting a fixed timestep.

Best regards,

Robert
<<

Hey,

the temperature was okay. Now, I fixed the time step adjustment too --> the temperature increased to 1.4e41. If I run a case with a simple box, one surface is inlet and an other is outlet --> it works. But in the special case I use a complex geometry (cyclinder and intake manifold of a combustion engine --> stl). Do you have an idea?

Best regards,

André
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Old   February 14, 2013, 11:00
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Niklas Nordin
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zero gradient velocity inlet condition!!!

you will never get that working.

try instead to specify the velocity at the inlet
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