Direct simulation of multiphase flows with modeling of dynamic interface contact angle
Résumé
We describe a modeling technique for dynamic contact angle between a phase interface and solid wall using a generalized Navier boundary condition in the context of a front-tracking-based multiphase
method. The contact line motion is determined by the generalized Navier slip boundary condition in order to eliminate the infinite shear stress at the contact line. Applying this slip boundary condition only to the interface
movement with various slip ratios shows good agreement with experimental results compared to allowing full
fluid slip along the solid surface. The interface slip model performs well on grid convergence tests using both
the slip ratio and slip length models. A detailed energy analysis was performed to identify changes in kinetic,
surface, and potential energies as well as viscous and contact line dissipation with time. A friction coefficient
for contact line dissipation was obtained based on the other computed energy terms. Each energy term and
the friction coefficient were compared for different grid resolutions. The effect of varying the slip ratio as
well as the contact angle distribution versus contact line speed was analyzed. The behavior of drop impact
on a solid wall with different advancing and receding angles was investigated. Finally, the proposed dynamic
contact model was extended to three dimensions for large-scale parallel calculations. The impact of a droplet
on a solid cylinder was simulated to demonstrate the capabilities of the proposing formulation on general solid
structures. Widely different contact angles were tested and showed distinctive characteristic behavior clearly.
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