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A 2D image-based approach to investigate the validity of CFD multiphase fluxes
Author(s): Paola Elizabeth Rodríguez-Ocampo, Michael Ring, Jassiel Vladimir Hernández-Fontes, Juan Alcerreca-Huerta, Edgar Mendoza, Gabriel G. Diez-Barroso, Rodolfo Silva
Keywords: : Numerical modeling, Turbulence models, Validation, Dam-break experiments
Multiphase flow phenomena can be of different types, e.g., with differences in the state of matter, densities, or temperatures, which in turn, demand different experimental setups and methods to perform numerical validations. For cases where the setup can be assumed to be two-dimensional (2D) and there is a mixture between liquids of different densities in a free-surface condition, this study proposes an image-based approach to evaluate the validity of numerical results. The proposed validation methodology is based on the estimation of the average error of the model through density matrixes generated from both images of the experiment and the numerical results. Average errors between the simulations and the experiments are considered to indicate the validity of the numerical results. To demonstrate the use of the methodology, both 2D experimental tests and numerical simulations were performed for a double wet dam-break problem, considering three fluid phases. For the experiments, a high-speed camera was employed to capture details of the fluid interactions after the dam-breaking. For the numerical simulations, an OpenFOAM® multiphase solver was employed to reproduce the benchmark tests, evaluating three different turbulence models. Qualitatively, a zero-equation and a two-equation k-ε Reynolds-Averaged Simulation (RAS) models seemed to be more precise for describing the formation of eddies in the initial phase of the experiment. However, quantitative results suggest that a Large Eddy Simulation (LES) model reproduces the mixture between phases more accurately. The present methodology could be improved and extended for different multiphase flow configurations.