Research On Viscous Liquid Sloshing And Its Interaction With Flexible Structure Based On Level-set Method

Liquid sloshing phenomenon in a liquid tank mounted on ship has caused people's profound attention and the sloshing loads and effects have become the important content of the safety evaluation of a sailing liquid cargo. In this paper, numerical simulation of liquid sloshing in a rectangle liquid tank is performed using Level-set method to track the free surface. The whole fluid field is described with a set of uniform general governing equations. With the conception of aperture and the hydroelasticity theory, the coupled interactions between liquid sloshing and elastic structures are studied. The major works of this paper are as follows.1. The mathematic model describing liquid sloshing is established on Level-set method. The general governing equations are solved with SIMPLE arithmetic, and the discrete N-S equation is performed with the combination of Leap Frog format and DuFort-Frankel format in MAC stagger grids. The Level-set equation is solved with integral average Superbee-TVD format, and the re-initial equation is solved with modified Godunov method in which the spacial differential coefficient is constructed using the fifth order WENO format.2. A method to deal with the transition of physical parameter crossing the interface is established which can achieve the numerical simulation of interface transfer of liquid-gas two phase flow which has a density ratio larger than 800/1 successfully.3. Using the conception of aperture, different structures are added to the tank and the effect of restraining sloshing are compared.4. Using the liquid sloshing hydroelasticity theory, the mathematic model that describing the coupled interactions between liquid sloshing and elastic structures are established and a series of calculations is carried out to predict the features of structure response.The following conclusions may be obtained from the works above:1. It is unnecessary to tracking the moving interface explicitly using Level-set method. And the topological changes of the free surface such as turning, breaking and merging can be dealt with conveniently.2. The method proposed in this paper that deals with the transition of physical parameter crossing the interface can avoid the calculation instability due to the large densityratio and can keep the reality of the physical model.3. With the application of the concept of aperture combined with Level-set method, the problem of sloshing with interior obstacles can be solved. The pattern of the anti-sloshing structure has obvious impact to the effectiveness of restraining sloshing.4. The amplitude and frequency of sloshing closely depends on viscosity and depth of the liquid, as well as dimensions of the tank. And the sloshing is sensitive to the excitations frequency.5. Different structure rigidities will lead to different structure responses, and the distortion of structure will influence the sloshing. If the distortion of structure is small, its effect is not obvious.