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# Seweryn Rek, MEiL, ZA, PW, Towards numerical modeling of the drop collision with the solid surface

S. Rek, T. Wacławczyk, J. Rokicki

Reliable and accurate modeling of many industrial processes requires*consideration* of interactions between two or more phases. Any fluid *flow* consisting of *more* than one *phase **i**n a domain is called multiphase flow*. Multiphase flows are classified as segregated or dispersed. In segregated flows which will be scope of the present studies the phases flowing through the domain are separated by deformable immiscible interfaces.

One of many possible applications of numerical modeling of multiphase flow is spreading of a liquid on a substrate. Spreading is an elementary phenomenon in many processes like adhesion, coating, or painting. Spreading is the dynamic way of covering a substrate with a liquid up to the point when the equilibrium state is reached. Practical application requires the knowledge of how fast a liquid droplet, can spread out and cover a given surface. Spreading phenomena are governed by the interplay of surface and interfacial interactions, in the region where the liquid meets the uncovered solid i.e. the region of the three-phase contact line. Modeling of three-phase contact line arises question of boundary condition for liquid flow on a solid substrate. While liquid molecules in contact with solid substrate don't move easily a standard boundary condition for liquid flow on solid substrates is the no-slip at the substrate. However, applying this boundary condition strictly would not allow for any displacement of a liquid on a solid substrate.

Further studies on multiphase flow will concentrate on the interface capturing Volume of Fluid method based on the idea of a so-called volume fraction function. To trace the evolution of the interfacethe additional transport equation for system on n-1fluids must be solved along with one-fluid formulation of the Navier-Stokes equations. In the present seminar the VOF method implemented in OpenFOAM solver is shortly addressed as this tool will be used in further studies. Moreover, in this presentation firststeps towards numerical modeling of the drop collision with the solid surface will be presented focusing on the numerical solution of the advection-diffusion equation.