Verification and Validation Study of OpenFOAM on the Generic Prismatic Planing Hull Form
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In this research, hydrodynamic analysis, verification and validation will be performed on Generic Prismatic Planing Hull (GPPH) using OpenFOAM v1806 solver interFoam. The numerical simulation will be compared with the experimental result, which is a new set of high-quality experimental tests performed on a large model of a high deadrise prismatic planing hull with flat of chine, tested from pre-planing to fully planing regimes. Firstly, the mesh convergence study and Verification and Validation (V&V) study are performed on the basis of fixed attitude simulations. Three grids are chosen and used to perform the free attitude simulations at the highest speed. Then, mesh convergence study is conducted for the results of highest speed free body simulations, which helps us to choose two grids for other speeds simulations. By performing free attitude simulations using two grids, resistance, heave, trim angle, wetted chine length, and wetted keel length are calculated and compared at seven different tested speeds. Computational Fluid Dynamics (CFD) results analysis regards pressure distribution on the bottom of the hull and in particular areas of interest (flat of chine, spray area, etc.), friction coefficient and volume fraction of fluid in areas where the free surface undergoes violent deformations (overturning wave at the chine and in the wake, spray jet development area). Different algorithms for dynamic mesh simulation and their effect on the quality of CFD predictions are also investigated.
General Audience Abstract
The paper presents the first series of results obtained in an ongoing validation and verification study of inter-dynamic OpenFOAM solver framework on a new set of high quality experimental tests performed on a large (2.4m long) generic planing hull model (GPPH) with high deadrise (18deg), from the pre-planning (Fn∇=2.6) to fully planing (Fn∇=5.7) regimes. This test case is a good benchmark for the free surface capturing model implemented in OpenFOAM which is based on a rather simple transport equation for an additional scalar field that defines the fraction of water in each cell of the computational mesh. This model, in spite of its simplicity, seems capable of reproducing complex violent free surface flows such as that observed in planing hulls, that includes jet spray forming on the bottom and detaching from the chine of the planing hull and overturning waves off the wet chine region, with some nuances. The dependence of the flow solution on the mesh quality is presented and discussed. Practical indication of the level of uncertainty of CFD models for the prediction of the calm water hydrodynamics of the GPPH is given at the highest simulated speed using both fixed and free attitude simulation solutions. Predictions are then extended to the whole speed range, including resistance components, dynamic trim, heave, wetted chine length, and wetted keel length.The effect due to algorithms is also discussed by modifying the settings in wall functions and solvers for the improvements of future simulation.
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