Free Surface Contact Angle

[jcs]

Hello OpenLB team,

I am attempting to use the free surface model to model filling of a cavity. This method suits me well (compared to multicomponent/free energy methods) as my gas phase is a vacuum. My fluid’s surface tension is very high (>1 N/m), which appears to make it wet strongly to the walls. The problem is that my fluid is strongly non-wetting (contact angle >130°).

Is there a way to set the contact angle for free surface?

I have seen in the below link that Mathias recommended changing rho on boundary nodes for multiphase, however this does not seem to change anything for free surface.
https://www.openlb.net/forum/topic/multiphase-flow-contact-angle-and-surface-tension-setting/

Many thanks,
James

[Maximilian]

Hi James,

As far as I understand it, the contact angle and the categorization into strongly wetting, non-wetting, etc. is only relevant if we want to model the interaction between liquid, gas and a solid phase.

The current state of the freeSurface model focuses solely on the interaction between liquid and gas (including an interface layer between these two). The solids are not taken into account with the freeSurface model and are handled via standard boundary conditions.

On a first glance I didn’t find any sources that discuss the wetting / contact angle aspect in freeSurface. Do you happen to know any references or sources so we can look into it and potentially expand the freeSurface model in this direction?

Maximilian

[jcs]

Hi Maximilian,

Many thanks for your response and clarifying the current implementation.

Below is a presentation that discusses a few different approaches for wetting and surface tension in free surface lattice boltzmann:
https://www10.cs.fau.de/publications/talks/2014/Bogner_Paris_DSFD_2014-08-01.pdf

James

[Author]

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