Learning Forum

[Nicolo]

Hinn I am running a rather slow two phase simulation with VOF and explicit mode . It is basically a pipe of 1mm diameter with hydrophilic walls and interfacial tension and surface tension are important for me. I have done my best to use the corsets mesh possible but still the time required for Fluent to simulate like 20 sec of the flow is really high.n In the beginning of my simulation there is not much happening (basically it will be mostly gas flowing while the liquid is being collected and initially it is immobile liquid). is it ok to start the first few seconds of simulation with high global courant numbers like 20 to 40 (my residuals are reduced by 5 order of magnitude with this courant number) or it is just to high? I have written in may places that is recommended for explicit scheme to keep global courant number below 1! What would be the maximum courant number you'd suggest I can go. nis 20 and 40 are too far to go and can I at least go with 4 instead of 1 if I still have convergence ?.Thanks in advance

[Amine Ben Hadj Ali]

Surface tension driven flows are very expensive as the time step scales with the grid resolution power 1.5 and inverse properoitla to root of surface tension.nkeep courant number limited to max 5 or 10,. If xplicit even lower and try to get the run quicker by using NITA.n

[Rob]

Re your other thread, you may want to think about patching water into the domain to reduce the amount of time needed in your solution. n