一种用于流固耦合分析的有限元网格简捷更新方法

Improved Finite Element Mesh Update Method for Fluid-Structure Interaction Analysis

针对流固耦合分析中的移动边界问题,在拟固体二步法的基础上,提出一种新的有限元网格更新方法:第一步(预测步),将流体网格作为指定位移边界条件下的拟固体,进行线弹性分析;第二步(校正步),根据第一步计算得到的应变场,采用主剪应变方法,赋予主剪应变较大的单元以较大的杨氏模量,对所构造的非均质固体进行运动分析,得到理想的更新网格.采用不同算法对不同运动类型(包括平动、转动、变形)和不同运动幅度下的二维、三维网格运动进行计算,结果表明:与一步法和Chiandussi法相比,文中提出的方法具有较强的适用性,能显著地减小单元的畸变,使网格保持优良的计算性能,适用于大变形流固耦合问题中的网格更新计算.

Based on the pseudo-solid two-step（PSTS） model,a new mesh update method-PSS-PSTS method is proposed to solve moving boundary problems for fluid-structure interaction analysis.In the first step（predictor）,a linear pseudo-solid model is first conducted to the fluid mesh subjected to prescribed displacement boundary.In the second step（corrector）,based on the strain field computed in the first step,PSS（principal shear strain） method endows the element with greater Young modulus due to its larger principal shear strain,then the motion of the established non-homogeneous solid model is computed and taken as the desired fluid update mesh.Some examples of 2D/3D FEM mesh update under different motion types（translation,rotation and deformation） and different motion scale computed by PSS-PSTS method are studied.The results show that the PSS-PSTS method is highly effective in preventing extremely distorted elements and makes the mesh maintain high computation quality compared with the one-step method and the two-step methods proposed by Chiandussi.It can be used for mesh update computation for fluid-structure interaction problems with large deformation.