'opening' type BCs with LES
 

Does any one use opening type boundary condition with LES. CFX manual does not suggest to use it with LES at all and I have also noticed that the solver fails with opening type BCs while doing LES.

Any comments or different experience please?

Regards,KK

Re: 'opening' type BCs with LES
 

Hi

Yes i used opening BC for LES simulation few days ago and it worked fine. I, then, used that simulation as an initial guess to start my real problem which was more complicated.

kasim

Re: 'opening' type BCs with LES
 

Hi,

An important issue with openings and LES is that the turbulent eddies can cause reverse flow out the boundary and this is numerically unstable. It is best to move the boundary upstream to somewhere the flow will not have regions of reverse flow.

Glenn Horrocks

Re: 'opening' type BCs with LES
 

not to mention that opening bcs will be reflective... use an average pressure outlet and move the bc as Glenn suggests.

Re: 'opening' type BCs with LES
 

You can use opening BC for an initial guess but dont use it for final solution. You can use non-reflective BC in CFX its one of beta option.

kasim