Numerical Simulation of slug flow in a micro-channel
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Multiphase dynamics and characteristics of slug flow in micro channels are investigated computationally by means of advanced numerical simulation methods. Although, due to its importance in many engineering and biomedical applications, the topic has been studied previously, methods for robust and accurate simulation of slug flow remain elusive. Evaluation of current state-of-the-art Computational Multi Fluid Dynamics (CMFD) technology depicts deficiency with advanced computational methods (Volume of Fluid (VOF), Level Set, Adaptive Mesh Refinement (AMR)), which fail to deliver physically sound results. The separation of temporal and spatial length scales in the thin liquid film, formed between the channel surface and the gas bubbles, verifies the foreseen multiscale nature in the slug flow. This indicates that perturbations from the micro-scale can effectively propagate up scale, rendering the macro-scale description (CMFD) inadequate. A Sub-Grid Scale model was developed for the treatment of micro-scale thin liquid film dynamics based on the Long Wave Theory. A novel multiscale-coupling between a Sub-Grid Scale (SGS) thin film model and a CMFD code is proposed to preserve the micro-scale perturbations on the macro-scale and to enable high-fidelity simulations without a dramatic sacrifice of computational time. First-of-a-kind "multiscale-simulations" for the treatment of the microscopic lubricating thin film show unique physical results.