inaccurate contact angle capturing in high shear/viscousity flow
 

It is a very interesting thread http://www.cfd-online.com/Forums/ope...tml#post264714, and I think the contact angle problem is still over there after 5 years which I'm struggling with currently.

Recently, I'm working on problems with moving droplets/bubbles driven by shear flow with high viscosity (high Ca number), where the contact angle is less accurately captured than in the cases with low viscosity (low Ca number) or quasi-steady cases.

it is stated in the thread nHat and nHatf are corrected based on contact angle in interfaceProperties.C, but alpha1 and snGrad(alpha1) are still inconsistent with contact angle on the boundary when it is used to calculate pEqn and UEqn, resulting in very bad contact angle. i have several questions referring to this problem:

correctContactAngle in interfaceProperties.C has corrected nHat on patches, and set fixedGradient value of alpha1 on patches based on it. Why field of alpha1 and snGrad(alpha1) cannot reflect the correction in contact angle?

Actually, I output and checked (nHatp & np) and (gradAlphaf & nf)/mag(gradAlphaf) in correctContactAngle function in interfaceProperties.C, they are very close to each other and difference is between 1%. It shows that nHatp, nHatf and gradAlphaf are correctly set on the boundary within interfacProperties.so, but why the gradAlphaf is not used to correct the alpha1 field to match the calculated fixedGradient BC even if I call alpha1.correctBoundaryConditions() in alphaEqnSubCycle.H

BTW, I'm using constant contact angle and OF211 current, limiter of alpha1 is set as alpha and p_rgh is fixedFluxPressure

Anyone has good idea or experience on imposing contact angle BC on alpha forcely on patches?

Thanks a lot