[mykkujinu2201]

Dear Forum,

Currently, I am preparing hybrid version of VOF (interFoam) and interface tracking method to prevent spurious velocity issue.
VOF will calculate pressure, velocity and marker while interface tracking method will calculate capillary force.
I referenced the paper of Mosayeb Shams. (Shams, M., Raeini, A. Q., Blunt, M. J. & Bijeljic, B. A numerical model of two-phase flow at the micro-scale using the volume-of-fluid method. Journal of Computational Physics 357, 159–182 (2018).
)
He made the code (CLSF, contour-level surface force method) in OpenFOAM and the base solver is interFoam.
Isocontour of marker is reconstructed to obatain interface elements.
According to Shams, intereface elements are constructed based on faces of fixed grid where sharpen marker changes rapidly.
Thus, each element has its corresponding face and they are called 'mixed face'.
After obtaining interface elements, capillary force is directly calculated for each element.
Finally the result will be interpolated back to mixed face to calculate flux due to capillary force.

I made the code and now I am validating it.
The validation cases are 2D and 3D static bubble simulations.
For 2D cases, spurious velocity is reduced below 10^(-10) m/s and it predicted pressure well. (Results of time series of max. spurious velocity and pressure along the centerline are attached.)

However, when I tested for 3D cases, the flow field does not converge showing spurious velocity issue.
I can not figure out the reason or the solution yet.

I tested 3D case in both serial and parallel run but results are same so I think this is not due to parallel computing part.
I exported control points of interface elements to compare.
However, the control points are well reconstructed.
In addition, if control points are not tracked well, same issue should come for 2D tests.

Does anyone had similar issue or any opinion?

Best,
Jun