In the ocean engineering field, highly nonlinear phenomena on the free surface, such as the wave impact on a floating body, must be more intensely studied, although we still have a long way to go. The imapct phenomena include the wave breaking, splash and/or mixture of air. For this difficult topic, we need a prediction method which gives quantitatively good estimation of the impact force acting on a body. We believe that the Computational Fluid Dynamics (CFD) will be a powerful tool for this kind of analysis.

In the free-surface hydrodynamics, capturing the interface between water and air (or another fluid with different density) is a key to the success. For that purpose, the density function method, CIP scheme, level-set method, and so on have been developed. We are now testing these schemes and trying to develop a new versatile method.

This research has actually just started and thus no results are obtained for the wave impact problem. The above figure shows an example of the results by CIP (Cubic Interpolation Pseudo-Particle) scheme, concerning the Kelvin-Helmholtz instability probelm. The densities of the upper and lower fuilds are 0.1 and 0.3 respectively, and the upper fluid moves from left to right with initial small disturbance. Then the interface develops, as shown in the figure, as the time proceeds.

Future plan in this research is to make it possible to predict accurately the impact pressure on a body which might be flexible and freely moving in waves.

Link to Useful Sites regarding CFD CODES
Home Page of Free-Surface/Interface Dynamics Section


Inquiries and comments are welcome at kashi@riam.kyushu-u.ac.jp