Free Liquid Drag−out from a Liquid Bath Using SPH

The liquid drag−out (LDO) coating process is a key process in metallic−coated strip production in continuous galvanising lines. The liquid is dragged−out by the strip when the strip pulls up from a bath. The liquid in the process is commonly liquid zinc. The LDO physical understanding is important to control the liquid film thickness, coated strip smoothness and production efficiency. The thesis aimed to understand free LDO fundamentals by developing a numerical tool to simulate the free LDO process. The LDO fundamentals (meniscus, stagnation point, re-circulation flow, boundary layer thickness) analysis are important, as the film is influenced by the fundamentals. A graphical processing unit (GPU) enables a Smoothed Particle Hydrodynamics (SPH) tool is to be developed using MATLAB. The SPH tool is validated against the numerical cases: lid−driven cavity, a hydrostatic tank under gravity and a droplet spreading on a solid surface. The inter−particle interaction (IIF) technique is used in modelling the surface tension and adhesion. Non−periodic inlet and outlet boundaries are present in LDO problem. Mirror buffer technique with SPH is implemented in the outlet to model the gradient−free Neumann boundary. Also, to conserve the domain mass over time, a novel approach is introduced to return the domain leaving particle immediately to the domain at the next time step.