Fluid-body interaction on a Cartesian grid: dedicated studies for CFD validation.

CFD methods are getting more and more popular to investigate applications in Fluid Dynamics. This is because of their versatility and robustness. An important issue for them is to assess the results sensitivity to the involved parameters, their physical correctness and accuracy. Especially if a Cartesian grid is adopted, the fluid interaction with generally shaped bodies is a challenging problem. In this framework the presence of a fluid interface complicates the numerical difculties. Generally speaking, errors in the enforcement of the body-boundary conditions will affect both the kinematics and dynamics. The sensitivity of the numerical solution to such errors depends on the examined problem. Figure 1 shows two practical examples: (i) the flooding phenomenon across a road and (ii) a freely oating ship in waves. In case (i), the water interaction with the terrain affects velocity and direction of the liquid propagation. In this case the boundaries are fixed and the description of the kinematics is of main concern. Differently, in case (ii) the numerical capability to handle the pressure field plays a crucial role because the body motions are coupled with the fluid dynamic problem.