Application Of Continuous Forcing Cut-Cell Method

A prominent issue facing the large LNG carriers traveling in high sea is liquidsloshing in partially filled tanks excited by the environment these vessels operate in,the wall strength and fatigue problem has caused more and more attention.Particularly, the elasticity could not been ignored for the membrane tank walls and theinteraction between the wall and fluid is more significant. Also, the vortex-inducedvibration (VIV) of flexible risers in deep sea belongs to the typical fluid-solidinteraction (FSI) problem.The Immersed Boundary Method (IBM) as a type of non-conforming meshmethod could be used to study FSI, achieving the interaction by adding the forcesource term in Navier-Stokes momentum equations and satisfying the velocity no-slipcondition on the interface. In this way, we do not need regenerating mesh and use thefixed Cartesian grid independent of the solid configuration, unlike the complexbody-fitted grid. Therefore, the significant characteristics of this approach are easy togenerate the computational grid and regeneration-free so the complex geometry andlarge deformation of multi-body could be described. Furthermore, the force terms inthe continuous force Immersed Boundary Method satisfy the particular mechanicalrelationship and generally have the explicit analytical expressions so it can solve theelastic boundary problem.Based on the in-house nonlinear two-phase large eddy simulation CFD platform,including the improved RBF cut-cell FVM technique and mass-force model, thispaper adopts the immersed cut-cell FVM to simulate the interaction between the fluidand the elastic boundary. By developing a class of numerical scheme based on thefluid volume and area fractions in cut-cell approach, the complex moving multi-bodycould be simulated, and the accuracy of the numerical method could be expected tobe improved. The paper contains6chapters:In chapter1I focus on the research status of the IBM, and propose the mainwork in this paper.In chapter2the mathematical model of the FSI using the IBM is built so we can understand its mechanism clearly. This part is the foundation of the whole paper.In chapter3the discretisation process of the unsteady incompressibleNavier-Stokes equations solved by the immersed cut-cell FVM is demonstrated.In chapter4the technique route in this paper is given.In chapter5the interaction between the fluid and the elastic boundary issimulated using the above numerical method.In chapter6the research work is summarized, also the further plan is proposed.