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Simulation of water entry and exit of a circular cylinder using the ISPH method

Simulations of free surface flows, as well as flows with moving boundaries in general, are quite difficult to describe with the classic, mesh-based Eulerian methods, such as finite difference, finite volume, and finite element methods. Meshless Lagrangian methods or a combination of Eulerian-Lagrangian methods that have the ability to describe the free surface with large deformations have been developing in the past fifteen years. In this paper, the Lagrangian incompressible smoothed particle hydrodynamics (ISPH) method for simulating the dynamics of an incompressible viscous fluid flow is presented. The ISPH method is an attractive choice for the simulation of incompressible fluid flow because it is based on the simple SPH formulations, and it solves the pressure field implicitly using the projection scheme of solving the Navier-Stokes equations. A computer code for the simulation of the viscous incompressible fluid flow based on the ISPH method is developed. Water entry and water exit of a rigid body are very important phenomena in marine hydrodynamics and there have been many studies and experiments on the topic. The cases of two-dimensional water entry and water exit of a circular cylinder at a forced constant velocity were studied in order to verify and validate the method. Numerical simulations of a rigid circular cylinder falling onto initially calm water at a constant entry velocity were carried out. Also numerical simulation of the water exit of a circular cylinder, initially fully immersed, was performed. The obtained numerical results are in good agreement with the experimental and analytical ones found in the literature.

incompressible smoothed particle hydrodynamics (ISPH) method ; water entry ; water exit ; circular cylinder ; free surface

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