A Ghost-node Immersed Smoothed Point Interpolation Method With Viscous Force Revision For Fluid-structure Interaction Problem

Studying fluid-structure interaction(FSI)problem by employing numerical simulation methods has gradually become the focus in recent years.The immersed smoothed point interpolation method(IS-PIM)has been proposed,which is based on the idea of immersed-type methods.In the frame of IS-PIM,subregional solving technique is used and fictitious fluid domain has been introduced to deal with FSI systems.When using original IS-PIM solving FSI problems,the FSI force is calculated through the Lagrangian grid of the fictitious fluid domain.However,the viscous force acting on the solid domain will be inaccurate due to ignoring the viscous force on the solid domain.This problem will be more obvious when the rigidity of the solid is greater,or the Reynolds number of the fluid is smaller.Therefore,based on the shortcomings of the evaluation of FSI force,a new form of FSI force evaluation in which the viscous force is calculated based on the fluid Euler grid has been introduced.By simulating typical FSI numerical examples,it is proved that the improved FSI force calculation with viscous force revision proposed in this paper has higher accuracy.In addition,as an immersed-typed method,there are some inherent problems using original IS-PIM when solving FSI problems.First of all,the fluid domain cannot accurately capture the boundary of the solid domain,which leads to the inaccuracy of the FSI boundary when calculating the FSI systems.Furthermore,after revising the problem of inaccurate FSI boundary,it is necessary to ensure that the revised method meets the continuity requirement at the physical aspect.Finally,the original IS-PIM has "fresh nodes" problem,that is,the fluid nodes will have oscillations in velocity and pressure values when the fluid nodes go outside of the solid domain from the inside of the solid domain.Based on the above problems,the Ghost-node technique,Mass source/sink algorithm and Sharp-interface method have been introduced respectively to correct the problems existing in the original IS-PIM.The revised method,together with the improved FSI force evaluation algorithm with viscous force revision,are collectively called the Ghost-node immersed smoothed point interpolation method(Ghost-node-ISPIM).The simulations of multiple FSI examples show that Ghost-node-ISPIM can effectively capture the effect of solid boundary,and the results are more accurate and stable than the original IS-PIM solution.Finally,based on Ghost-node-ISPIM,the numerical simulation of the flow control problem in the case of low Reynolds number(Re=100)is carried out.Specifically,by studying the situation of placing a rigid or flexible detached plate at the tail of a two-dimensional cylinder,the flow control mechanism of drag coefficient and lift coefficient of the cylinder is studied.It is found that when the rigid plate control and the flexible plate control are adopted,the optimal position of the plate is different,and generally speaking,the control effect of the rigid plate situation is better than the control effect of the flexible plate.