Problem with BC + ReactingFOAM + gravity
I searched for a problem looking like mine on the forum, but I could not find such a topic, so here is a new one !
My computation domain is a channel, in which air is flowing, while an other gas is injected in the middle.
To adress this problem, I use reactingFOAM.
For my first runs, I forgot to set the gravity vector to -9.81 u_z.
I obtained physical pressure and velocity fields.
But when I realized my mistake, I 'activated' gravity. Doing so, I got weird velocity and pressure fields for the corresponding runs.
Especially close to outlet BC where a recirculation zone appeared.
Big differences between theoretically very close runs.
(If useful : outlet BC are zeroGradient for U and fixedValue (1 atm.) for p)
How do you explain the differences ?
Which solution could you advise to me ?
I was considering the option to try to create a simplified version of reactingFOAM, as my case is non-reactive, but I'm not sure that this work would help me ...
Thanks in advance for your help ...
Could you please post your files from the 0-directory and a screenshot of the strange flow behaviour you're talking about?
I'm dealing with a similar problem and perhaps I can help you. But I need a little more detailed information. ;)
I'll try to upload more precise elements. For the fields, I have roughly :
- a recirculation zone at the outlet
- a depression at the outlet. In the channel, pressure is not homogeneous. I mean, pressure is slightly higher in the lower part than in the upper part of the channel. For the case ran w/o gravity, pressure is homogeneous.
The pressure gradient is typical of gravity-influenced cases.
It should be something like dp/dy = g*rho [Pa/m]. (Please correct me, if I'm misled.) You will find this pressure gradient in our atmosphere, too.
Concerning the recirculation zone I can't say anything until I've seen your BC files and a screenshot would really help my imagination, too. ;)
I am very interested in the solution to this matter. I am also doing a case on air flow and gas injection, using reactingFoam. Like Gloq I obtain this circulation zone at the outlet when gravity is set.
Did you discover a solution to the matter?
Could it be possible to use f.ex. fireFoam, or rewrite solver to solve for p_rgh?
|All times are GMT -4. The time now is 21:44.|