A CFD model is proposed for numerical simulations of extremely nonlinear free-surface flows such as wave impact phenomena and violent wave–body interactions. The constrained interpolation profile (CIP) method is adopted as the base scheme for the model. The wave–body interaction is treated as a multiphase problem, which has liquid (water), gas (air), and solid (wave-maker and floating body) phases. The flow is represented by one set of governing equations, which are solved numerically on a nonuniform, staggered Cartesian grid by a finite-difference method. The free surface as well as the body boundary are immersed in the computation domain and captured by different methods. In this article, the proposed numerical model is first described. Then to validate the accuracy and demonstrate the capability, several two-dimensional numerical simulations are presented, and compared with experiments and with computations by other numerical methods. The numerical results show that the present computation model is both robust and accurate for violent free-surface flows.

A CIP-based method for numerical simulations of violent free-surface flows

Experimental and numerical hydrodynamic analysis of a stepped planing hull

An adaptive hierarchical grid based method for predicting complex free surface flows is used to simulate collapse of a water column. Adapting quadtree grids are combined with a high-resolution interface capturing approach and pressure based coupling of the Navier Stokes equations. The Navier-Stokes flow solution scheme is verified for simulation of flow in a lid driven cavity at Re=1000. Two approaches to the coupling of the Navier-Stokes equations are investigated as are alternative face velocity and hanging node interpolations. Collapse of a water column as well as collapse of a water column and its subsequent interaction with an obstacle are simulated. The calculations are made on uniform and adapting quadtree grids, and the accuracy of the quadtree calculations is shown to be the same as those made on the equivalent uniform grids. Results are in excellent agreement with experimental and other numerical data. A sharp interface is maintained at the free surface. The new adapting quadtree-based method achieves a considerable saving in the size of the computational grid and CPU time in comparison with calculations made on equivalent uniform grids.

Simulation of viscous water column collapse using adapting hierarchical grids

Numerical investigation of the effects of turbulence intensity on dam-break flows

A further development of the QALE-FEM (quasi-arbitrary Lagrangian–Eulerian finite element method) based on a fully nonlinear potential theory is presented in this paper. This development enables the QALE-FEM to deal with three-dimensional (3D) overturning waves over complex seabeds, which have not been considered since the method was devised by the authors of this paper in their previous works (J. Comput. Phys. 2006; 212:52–72; J. Numer. Meth. Engng 2009; 78:713–756). In order to tackle challenges associated with 3D overturning waves, two new numerical techniques are suggested. They are the techniques for moving the mesh and for calculating the fluid velocity near overturning jets, respectively. The developed method is validated by comparing its numerical results with experimental data and results from other numerical methods available in the literature. Good agreement is achieved. The computational efficiency of this method is also investigated for this kind of wave, which shows that the QALE-FEM can be many times faster than other methods based on the same theory. Furthermore, 3D overturning waves propagating over a non-symmetrical seabed or multiple reefs are simulated using the method. Some of these results have not been found elsewhere to the best of our knowledge.

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QALE‐FEM for modelling 3D overturning waves

We present the results of simulations obtained with a free-surface flow solver based on the following method. The free surface is simulated by the “volume-of-fluid” interface capturing method. This code solves the Navier–Stokes equations using a finite-volume method adapted to a structured or unstructured mesh. The system is constructed using a fully coupled approach. This global approach allows the simulation of complex flow as a breaking or merging wave. Moreover, with the use of a 2D+T decomposition, it is possible to simulate three-dimensional steady flow.

Yann Andrillon

Papers

A 2D+T VOF fully coupled formulation for the calculation of breaking free-surface flow

SPH Free Surface Flow Simulation

Systematic study of the hydrodynamic forces on a Volvo 70 racing yacht using parametric design, CFD and variable selection