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Error:Global Courant Number is greater than 250

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Old   September 13, 2015, 22:47
Question Error:Global Courant Number is greater than 250
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Hi All,

I'm trying to replicate an experimental set up of two capillary-held air bubbles in water by using fluent. Dimension of capillaries are 0.69mm inner diameter and 1.07mm outer diameter, 3.5 mm of length. Bubbles diameters are 2mm. The capillaries are immersed in a box that has 6X7X5 mm dimensions. There is a compressed air inside the capillaries and the box has water.
I have patched the two bubbles at the bottom of the capillary with air. I also patched the inside of capillary tubes with air.

It's a pressure-based solver. I'm using VOF as a model. Primary phase is water and secondary phase is air. In Boundary Conditions, I set an Air_Inlet (air coming into capillaries)as a pressure inlet, a free_surface (top face, perpendicular to capillary tubes) as a pressure-outlet.

Solution Scheme is Piso. Time step size 1e-05, number of time steps 4000, Max iteration 80.

When it starts calculating, an error come out saying that global courant number is greater than 250. I don't know why, if I have very small time step size.

Thanks in advance for your comments, I really appreciate.
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