Dynamical Response of a Newtonian Fluid Interface to Mixed Oscillatory Deformations

In this work, the behavior of a slender probe floating horizontally on a water/air interface with specific interfacial properties, namely shear, dilational, and extensional viscosities, is simulated using the finite volume method. The aim is to analyze the feasibility of separating the components due to each of the mentioned deformation modes. The system consists of a small diameter cylindrical probe (typically 400 microns) placed horizontally on a water/air interface; the floating probe, submerged to its median plane by capillary effects, moves sinusoidally in the direction perpendicular to its axis.

To carry out the analysis, the interface dynamics equations were implemented in the open-source software OpenFoam. The behavior of the probe was simulated for Marangoni numbers between 1 and $10^5$, combined with ratios of the dilational rate to the shear stress $\Theta$, between 1 and $10^5$. The behavior of the probe was successfully simulated, and the forces exerted on the probe by the different deformation modes were calculated.