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-   -   multiphase jet (http://www.cfd-online.com/Forums/fluent/30418-multiphase-jet.html)

Nicolas Huybrechts October 21, 2002 07:56

multiphase jet
 
Hello

i try to simulate a water jet flow in a tube but it doesn't converge.

I use the VOF model and the time step is 1e-6.

the water can't come in the air tube.

does somebody have already studied a such flow?

Nicolas

david October 22, 2002 09:25

Re: multiphase jet
 
What type of VOF did you use? Whats the BCs at the edge of receiving cylinder? Type of mesh? DC

nicolas huybrechts October 22, 2002 10:58

Re: multiphase jet
 
I first use the VOF with Geo constructor.

Then i use the mixture model with the slip velocity option.

When i use fuel in a water tube, both methods converge but the time step selected by the time adaptive is very smaller with the VOF (1e-5 after some iterations) than with the mixture model (0.1s after some iterations). At initialization, the time time is 1e-4

but when i use water (or fuel) in a tube full of air, the VOF doesn't converge.

the geometry is a 2d'one.

It consist of a small tube connected to a bigger one

As BC, i impose :

inlet of the small tube velocity: 1 m/s fraction volume 1 turbulence intensity and diameter

inlet of the big tube atmospheric pressure

outlet atmospheric pressure

the mesh is hexahedral without boundary layer but the mesh is raffined near the connection of the tubes

Nicolas


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