[fbsims]

Hi,

I'm modelling a fluid flow in a pipe and to save time am trying to simulate only a 30 degree section. At the moment I've just set an inlet velocity of 3m/s but the resulting contour is not correct with a constant 3m/s flow across the domain, it doesn't seem to be accepting my periodic BC's and can't figure out why. the velocity contour and BC's are shown in the screenshots.

I can't make this 2D and use axisymmetric as later on I need to add a droplet DPM spray which requires 3D.

How do I correct this?

Thanks

[LuckyTran]

How are you sure it is NOT periodic?

And why is your pipe NOT a pipe? There is an outflow and you have 0 walls.


You should have 5 surfaces (more if some are redundant). At least 1 should be a wall. Two of them need to be coupled via a periodic BC. One more for the inlet, one for the outlet.

[fbsims]

Sorry should have further specified. It's not actually a pipe, its a cylindrical domain of atmospheric conditions so the red is pressure outlet of atmospheric pressure. I want there to be a constant 3m/s airflow from one end to the other so i set up a velocity inlet of that magnitude. I don't think it is periodic because the vertex of the wedge has velocity going to 0m/s towards the end. I think it should be entirely 3m/s if it is periodic as that is essentially just the inner part of my atmospheric cylinder with constant 3m/s air entering from the side. So i have one inlet, 2 outlet (the end and the top) and then the two periodic faces)

[LuckyTran]

You have violated mass conservation. Keep it up! You might violate momentum and energy conservation next! And then the universe will explode

[fbsims]

You evidently understand what's wrong here so do you have a suggestion as to how to correctly implement this flow field?