The Numerical Simulation On The Interaction Of Oceanic Internal Solitary Waves With The Submerged Body

Internal solitary waves are a kind of special internal waves, which could bring enormous energy and propagate long distance in the ocean with its wave form basically unchanged. When submerged body encounters such strongly nonlinear internal solitary waves, its stability, maneuverability or even security will be greatly affected. The serious problems have caught both the Governments'and the military's attention all over the world, but at present solutions in practical application are still quite limited. In response to the strategy of Maritime Power in our country, the investigation on the interaction of internal solitary waves with submerged body is not only academically important, but is of considerable importance in practical application.On the basis of reviewing and summarizing recent researches of such a problem, based on the secondary development function of the CFD software FLUENT, with the interface of two-layer fluids tracked by volume of fluid (VOF) method, wave entry condition given by setting wave-generating boundary method, and wave absorbing dealed with numerical dissipation method, a numerical internal solitary wave flume that allows submerged body to exercise its motion completely and steadily is developed. The interaction between internal solitary waves and fixed submarines (rectangle and 6:1 ellipse) is numerically simulated by use of the proposed numerical flume. The external dynamic loads on the submarine due to internal solitary waves are presented, showing that the maximum forces appeared when the submarine is located in the peak of the internal solitary wave; as the difference of surface geometry, the hydrodynamic force of 6:1 ellipse is more fairing than that of rectangle. The sliding mesh method is established to simulate the 2DOF (two degrees of freedom: pitch and heave) motion response of floating body under the interaction of internal solitary waves. It is improved to accurately describe the nonlinear phenomena of ship-wave interactions. The results shows that the body's posture will change a lot and can move quite severely; taking into account of restoring moment, longitudinal trim of the submarine is not so severe as mentioned above,but it is more bumpy; the external dynamic loads on the submarine are different from that of fixed conditions too.It should be noted that this work is the first step of wave-body coupling between internal solitary wave and submerged body in numerical simulation field. This work has verified that internal solitary waves have important influence on the security of underwater craft. The work can be the scientific instruct for the profile optimized design, strength design of the submarine, or even the operation that to avoid the harm by internal solitary waves.