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Need assistance in BC's for simulation of Vacuum cleaning nozzle

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Old   May 22, 2009, 13:56
Default Need assistance in BC's for simulation of Vacuum cleaning nozzle
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bruce
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Hello All

I am simulating vacuum cleaning nozzle (only half model) with density at inlet 25 degree Celsius, 70 litre/s fluid flow and outlet Pressure boundary.!

Here is my problem setup,

MESH:

Generated mesh in SnappyHexMesh-1.5.x
2.4 million cells


0/U:

....

inlet
{
type flowRateInletVelocity;
flowRate 0.07;
value uniform (0 0 0);
}

outlet
{
type pressureInletOutletVelocity;
value uniform (0 0 0);
}
symmetry
{
type symmetryPlane;
}


0/p:

....


outlet
{
type fixedValue;
value uniform 0;
}

inlet
{
type zeroGradient;
}

symmetry
{
type symmetryPlane;
}

But for some reason U & p getting exploding after 5-10 iterations.

PS:
-I have 1.5mm gap between the floor and the vacuum cleaning nozzle, is that the reason?

-Based on the outlet boundary area, i calculated the outlet velocity it comes to around 100m/s, is that realistic? is that the reason for divergence? it could be more near the nozzles and floor!!!

-I am using kEpsilon turbulence model with inlet k=0.0026 & epsilon=0.0002

Can anybody suggest me what is wrong, with the simulation. I will be glad to provide all information if necessary.

Thanks & kind Regards
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