Experts in momentum loss please help
 

Hi,

i have a flow problem which restricts flow differently in different portions. should i create a single domain and have subdomains which represents different directional loss OR several domains of the different directional loss and link them using domain interfaces?

Re: Experts in momentum loss please help
 

Hi,

I am just curious what is meant by 'restrict flow differently in different directions'? What does this mean physically? Do you mind telling me a little bit about the principle?

Thanks, Ruchi

Re: Experts in momentum loss please help
 

Ruchi,

if an element in CFX has isotropic permeability, it means that the slowing down of flow thru that element is uniform irregardless of the direction. I'm trying to simulate anisotropic permeability ..meaning flow restriction/or slowing down is different in for different directions.

Re: Experts in momentum loss please help
 

Hi Jemteo, You can create one single domain and then create sumdomains with different directional loss values.

Re: Experts in momentum loss please help
 

Dear Jemteo,

Have you contacted your CFX Help desk? Are you using Fluid or Porous domains. There are multiple ways of doing these, and some are well documented..

If you are using Porous domains, and need anisotropic porosity (as in CFX-4.x) ask your CFX help desk on how to access that functionality... It seems to be a beta feature..

Good luck, Opaque..

Re: Experts in momentum loss please help
 

Jemteo:

There are alot of ways you can do this. You can also accomplish this using a single domain, using general momentum source/sink with expressions that limit the effected region to only a portion of the area.

I have used this to increase the complexity of the resistance region in already defined models. In my particular case I used 3 step functions to confine the sink to a cubical area within a larger domain.

Re: Experts in momentum loss please help
 

hi thanks for the help. i'm using CFX-5.x. still trying at it... i m also using transient flow.....getting oscillating rMS not sure if it is converging nicely

Re: Experts in momentum loss please help
 

when i use each zone (of different momentum) as subdomains my convergence faces a WALL HAS BEEN PLACED AT PORTIONS ....(at 100% of the faces...) but when i use each zone as different domains (and strangely CFX automatically creates interfaces) my convergence now has less than 40% with walls being placed.....

can anyone shed some light on this?

txs