[Sebastian3232]

Hi everyone,
Currently I am simulating a rectangular domain, in which I use VOF (volume of fluids) method, If I simulate it in 2D, after transient simulation, I got separated values of volume fraction between the fluids (Polyurethane as 1 and Air as 0 valules).
When I try to simulate the same field in 3D, after simulate the same ammount of steps, I got results in which values are not just 1 or 0 for the fluids, but I got a variety of values (as this fluids would not be mixed). I am using the same settings for both simulations except of the gravity value setting.
I would like to ask you all if have any clue of setting the model in a better way in order to obtain right results.
Thanks so much for your great help in advance.

[arjun]

your courant number may be very high and the interface tracking scheme may be making it too diffusive.


I wish i could be help more but i have not seen Fluent's theory guide after year 2015 so i do not know what they are doing in current versions.

[Sebastian3232]

Dear Arjun thanks so much for your reply,

By default the VOF model at ansys has 0.25 as courant number value. I will check more in detail interface tracking scheme to try better results.
Thanks so much.

[arjun]

Originally Posted by Sebastian3232

Dear Arjun thanks so much for your reply,

By default the VOF model at ansys has 0.25 as courant number value. I will check more in detail interface tracking scheme to try better results.
Thanks so much.

Is it possible for you to share the fluent theory manual, so that I can also see what is happening. ( my email is zxaar@yahoo.com )



Someone once told me that there is a scheme in Fluent that can keep interface sharp even at higher courant numbers. I tried on find details on internet but could never find it out.

[Sebastian3232]

Good day dear Arjun, I have sent an email to you with the ANSYS user guide, theory guide and tutorial guide, I also put the wetransfer link here
https://we.tl/t-KS4Mv8Ps82


Thanks so much.
Best regards

[arjun]

Originally Posted by Sebastian3232

Good day dear Arjun, I have sent an email to you with the ANSYS user guide, theory guide and tutorial guide, I also put the wetransfer link here
https://we.tl/t-KS4Mv8Ps82


Thanks so much.
Best regards

Thank you very much, I downloaded and looked.



I did not find anything special as far as details go but someone argued with me that the scheme "Compressive" on page 604 keeps the interface sharp. He claims that even at higher courant numbers it can.



So is it possible for you to try it.


PS: This scheme is coming from CFX and it seems to be very good.

[Sebastian3232]

I will try this right now, thanks so much dear Arjun.


Best regards.

[Sebastian3232]

Good day dear Arjun, I have tried compressive scheme at Fluent, and I got the same results, now I am trying to change other aspects but I haven´t got good results.


My best regards,

[arjun]

Originally Posted by Sebastian3232

Good day dear Arjun, I have tried compressive scheme at Fluent, and I got the same results, now I am trying to change other aspects but I haven´t got good results.


My best regards,

Something very strange. Could you just for test run sometime for time step that is smaller by 5 times.


If it produces better results then it is courant issue that is bothering this calculation.

[Sebastian3232]

Dear Arjun, I am testing right now. I will tell you my results as soon as simulation ends