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Wenbin October 29, 2003 13:38

boundary conditions for free surfae modelling

I am trying to model the wigley hull using Fluent VOF model, but not sure what type of BCs should be used, e.g. for the water/air boundaries. I haved tried velocity inlet for the water and pressure-inlet for air, but had no luck getting convergence. should I use pressure-inlet for the "free" boundary? It is mentioned in the Fluent doc.

Any help would be very appreciated.


mateus October 30, 2003 06:24

Re: boundary conditions for free surfae modelling

Hm you have a problem there...I woul also probabilly use velocity inlet and pressure inlet...try it only with pressure inlet od velocity inlet. What boundary do you use for outlet? You will get preblems with pressure reflections - in your case wave reflections - this may also be a reason for bad stability. You should use nonreflecting bc for outlet...



Wenbin October 30, 2003 11:33

Re: boundary conditions for free surfae modelling

Could I use velocity inlet for the outlet? if not, then what else should I use, general outflow might be the only one appropriate. I come from aero backgroud, never tackled this type of problem, more detailed advice will be very helpful.



mateus November 3, 2003 04:57

Re: boundary conditions for free surfae modelling

There are more things you can do to avoid wave reflection, but i'm not shure what can cou do in fluent. If you use compressible flow a nonreflecting boundary condition can be applied. Otherwise make shure you use very long mesh, soi thet waves become very small before hitting the boundary. You can also make a reginon of highly compressible material (to damp the wave) before boundaries...

I really don't know how to preceed in this case...



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