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To evaluate the application of the filter-based model(FBM), the modified RNGκ-ε, the FBM model with different filter sizes are used to simulate the cloud cavitating flows around a cascade hydrofoil. The calculation results are compared with the experimental data. It is shown that the fit filter size FBM turbulence model can capture the detail process of the vortex shedding in the rear part of the cavitating region better, while considering the effect of the turbulence in the cavitation model. The lift force and the drag force are more accordant with the experiment with a suitable filter size. [ABSTRACT FROM AUTHOR]

To assess a modified RNG κ - ε turbulence model, the cloud cavitating flow around a Clark-y hydrofoil is investigated using RNG κ - ε turbulence model with a modified turbulence viscosity coefficient, and the coefficient is related to the vapor and liquid densities in the cavitating region. The time evolutions of the shape of cloud cavities, the lift and drag force around the hydrofoil have been obtained, and compared with experimental results. It is shown that the modified model can predict successfully the characteristics of cavitation and the detailed process of the cavitation shedding. Values of n in the modified coefficient are found to have a strong influence on the cavity length, the vapor volume, the lift and drag force, but no significant effect on the frequency distribution of the dynamics around the foil is observed. [ABSTRACT FROM AUTHOR]

The application of a filter-based model (FBM) for the computations of cavitation flow is studied based on the flow around a cascade hydrofoil. With reference to the largest grid size of the refined region near the hydrofoil, four filters were selected in the FBM model. Through comparison with the results of the experiment and the standard κ - ε model, the effects and selection of the filter size were studied at the aspects of cavity shape and drag prediction. The results shown that the turbulent viscosity correction by the filter function is mainly done at the region of cavity shedding in the rear part of the hydrofoil, and the correction is increased with the decrease of the filter size. Considering the resolving capability of the grid for the turbulence scale, the filter size is proposed to be a value a bit larger than the largest grid size of the refined region. [ABSTRACT FROM AUTHOR]