# interFoam, dynamic contact angles and moving walls

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December 9, 2019, 03:38
interFoam, dynamic contact angles and moving walls
#1
New Member

Alexander Meier
Join Date: Feb 2017
Posts: 15
Rep Power: 9
hi all,

i'm trying to simulate the wetting of a moving wall with dynamic contact angles.
So as a very simple test case i made a vertical rectangular channel half filled with water and one wall moving. (see attached image)

the boundaryconditions for the moving wall are:

alpha.air:

type dynamicAlphaContactAngle
theta0 130;
thetaA 110;
thetaR 150;
uTheta 1e-07;
value nonuniform List<scalar>
...

U

type fixedValue
value uniform (0.01 0 0);

it seems to me - also looking at the code which i halfway understant - that for the calculation of the dynamic contact angle only the fluid velocity is used and not the relative velocity of the fluid with respect to the moving wall --> this results in a contact angle with the wall of 130° instead of 170° (the calculation of the contact angle in this BC are a bit odd)

An error to report? or is there another way to choose the velocity BC?

Attachment 73765
Attached Images
 interfoam_error.jpg (61.3 KB, 62 views)

 August 15, 2020, 02:56 #2 New Member   PRoy Join Date: Apr 2013 Posts: 1 Rep Power: 0 Probably you have already found a solution to this issue. If not, then I should mention that this is a known bug in the dynamic contact angle BC. You can read this bug report: https://bugs.openfoam.org/print_all_...-1&show_flag=0 A possible fix has been suggested: Line 145 of dynamicAlphaContactAngleFvPatchScalarField is where the calculation is being done. Change this line to : Code: `return theta0_ * (1 - tanh(uwall/uTheta_) * sign(uwall/uTheta_) ) - thetaA_ * neg(uwall) * tanh(uwall/uTheta_) + thetaR_ * pos(uwall) * tanh(uwall/uTheta_);` flowgeek likes this.

 August 17, 2020, 02:58 #3 New Member   Alexander Meier Join Date: Feb 2017 Posts: 15 Rep Power: 9 hi, thanks for the reply and the suggested solution! no i haven't found a proper solution to the issue - i had to cheat quite a bit... (can you post the link to the bug report again, or the issue number? i cannot open it...)

March 16, 2024, 11:28
#4
Member

Michael Sukham
Join Date: Mar 2020
Location: India
Posts: 78
Rep Power: 6
How did you quantify the contact angle on the moving wall? I have a moving wall which pushes fluid so I have a moving line contact angle on the curved surface of the cylinder. i am assuming that assigning zeroGradient which ensures 90 degree contact angle results in wiggles when the liquid bulk rises due to the moving wall. Is there something which I can do?
Attached Images
 shotSleeve.png (17.8 KB, 2 views)