InterFoam simulation - mesh setup

Nic86 · January 23, 2020, 20:42

Hello everyone,
I am trying to create an interFoam model setup which includes all the features that I will need in the future to run my hydraulic simulations.
I created a 3D closed channel (a culvert) and, with the help of some user on this forum, I managed to make it run (not sure if smoothly tho).

At the inlet patch I set a volumetric flow rate which I progressively increased because I was curious to see what would have happened when the water touches the soffitt of the culvert (and obviously things did not go right, and that's why i am writing

).

I attach here a screen shot of my mesh:

The red walls are set as "wall" patch while the top grey one is name atmosphere. For the atmosphere a "totalPressure" boundary type set to 0 is specified.

The meshing has some issues that i'd like to solve: the problem is that the soffitt of the culvert should be type "wall" itself (the channel is closed at its top) while actually is not.

The following screenshot is a plot of the alphawater:

The channel is almost everywhere full and I'd expect to have high pressure of water.

However, as you can see in the following figure, the pressure is everywhere equal to zero (except at the outer side of the bend).

I believe that this is due to the location of the patch "atmosphere", which force the whole domain to be set at zero pressure.

Where should i locate the "atmosphere" patch then?
Can anyone help me please?

If anyone have time to download the model (and modify it), it can be downloaded from here : https://www.dropbox.com/s/w4rr076vyc...hness.rar?dl=0

Thank you,
Nic

Nic86 · January 28, 2020, 02:37

Hello everyone,
I am trying to solve the problem explained above.
Since I believe that the atmospheric patch (where the total pressure is set to 0) should be set higher than the max water level, I modified the original geometry as shown in the following image:

I have created a dummy channel on the top of the original channel, where all the grey surfaces shown are set as "wall".
Then, I set the lid of the dummy channel (red in the next figure) as atmosphere patch:

In SALOME, i meshed the two channels separately and then merged the two meshes with the "Build Compound mesh" tool.

However, the interFoam does not run (it calculated smaller and smaller time steps and then eventually crashes). I believe it could be due to meshing errors. In particular, the interface between the two original meshes has duplicate/overlapping cells:

Does anyone know how to solve this issue in SALOME?
Is this the correct way to solve my problem?
Thank you.
Nic

January 23, 2020, 20:42	InterFoam simulation - mesh setup	#1
Nic86 New Member Join Date: Nov 2019 Posts: 24 Rep Power: 7	Hello everyone, I am trying to create an interFoam model setup which includes all the features that I will need in the future to run my hydraulic simulations. I created a 3D closed channel (a culvert) and, with the help of some user on this forum, I managed to make it run (not sure if smoothly tho). At the inlet patch I set a volumetric flow rate which I progressively increased because I was curious to see what would have happened when the water touches the soffitt of the culvert (and obviously things did not go right, and that's why i am writing ). I attach here a screen shot of my mesh: The red walls are set as "wall" patch while the top grey one is name atmosphere. For the atmosphere a "totalPressure" boundary type set to 0 is specified. The meshing has some issues that i'd like to solve: the problem is that the soffitt of the culvert should be type "wall" itself (the channel is closed at its top) while actually is not. The following screenshot is a plot of the alphawater: The channel is almost everywhere full and I'd expect to have high pressure of water. However, as you can see in the following figure, the pressure is everywhere equal to zero (except at the outer side of the bend). I believe that this is due to the location of the patch "atmosphere", which force the whole domain to be set at zero pressure. Where should i locate the "atmosphere" patch then? Can anyone help me please? If anyone have time to download the model (and modify it), it can be downloaded from here : https://www.dropbox.com/s/w4rr076vyc...hness.rar?dl=0 Thank you, Nic Last edited by Nic86; January 28, 2020 at 02:39.

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January 28, 2020, 02:37		#2
Nic86 New Member Join Date: Nov 2019 Posts: 24 Rep Power: 7	Hello everyone, I am trying to solve the problem explained above. Since I believe that the atmospheric patch (where the total pressure is set to 0) should be set higher than the max water level, I modified the original geometry as shown in the following image: I have created a dummy channel on the top of the original channel, where all the grey surfaces shown are set as "wall". Then, I set the lid of the dummy channel (red in the next figure) as atmosphere patch: In SALOME, i meshed the two channels separately and then merged the two meshes with the "Build Compound mesh" tool. However, the interFoam does not run (it calculated smaller and smaller time steps and then eventually crashes). I believe it could be due to meshing errors. In particular, the interface between the two original meshes has duplicate/overlapping cells: Does anyone know how to solve this issue in SALOME? Is this the correct way to solve my problem? Thank you. Nic