Weak Coupling Algorithm For Fluid-Structure Interaction And Analysis Of Wind Load And Membrane Structure Interaction

The problem of the fluid-structure interaction on membrane structure and wind loads has become one of the attractive issues in the field of the structural wind engineering.Based on the computational fluid dynamics(CFD) and the computational structural dynamics (CSD),the structure-fluid(mainly wind) interaction is simulated numerically using weak coupling algorithm.In each time step,the structure and fluid equations are solved by iterative algorithm in turn.The results computed from the first physical field are imposed on the second one as the outside loads.The main works are as follows:1.As the basis of numerical simulation technology,the basic governing equations of the computational fluid dynamics(CFD) are studied firstly and the formula derivation about the mass and the momentum conservation equation are done.The key elements and techniques of the numerical wind tunnel are studied and analyzed.The basic idea of CFD is expatiated and the whole working process is presented.Discrete methods of the control equations based on the finite volume method and the PISO algorithm about the fluid numerical computation are researched also.As concerning the turbulence simulation of the wind,the standard k-εmodel based on the Reynolds-Averaged Navier-Stokes is adopted. The formula derivation of the standard k-εmodel is done.2.The iterative solution process of the weak coupling algorithm is presented.It has three basic elements:the structural solver,fluid solver and control procedures.In accordance with the information provided by the CSD and CFD grid,the bucket search algorithm and various matching criteria are used to determine the transmission paths between the different procedures.Then the interpolation coupling parameters are established.3.For the data transfer and information exchange on the coupling interface,a fast Gaussian integral algorithm,used for load information transferred from fluid grid to structure grid,and a conservation algorithm,used for the geometric deformation transferred from structure to fluid grid,are provided.In addition,the linear interpolation and Hermitian polynomial interpolation are adapted to make the fluid and structure calculations syncronized. Thus the problem of the computational information exchange between the two software programs is solved successfully.4.Furthermore,moving mesh technique is introduced to make the displacement of the CFD grids change with the movement and the deformation of the structure.And the relevant computational programms are written,in order to keep the whole fluid grids from distortion due to the movement of the boundary.5.Finally,based on the above platform,coupling effects on membrane structures and wind loads are calculated and studied,and the feasibility of the proposed weak coupling algorithm is verified.The analysis of the example shows that the numerical wind tunnel is an effective way to solve the problem of wind and structure interaction,which will establish the foundation for the comparison with the numerical simulation and the experimental data in the next step.