Eddy resolving simulation methodology for dynamic fluid-structure interactions of lightweight flexible surface structures

该项目的目标是开发一种优化的方法来模拟湍流气流中轻量化柔性结构的瞬态流固相互作用。在轻量化结构设计中，与湍流强涡流的强相互作用至关重要。在第一阶段，考虑到两个领域的特定属性和特征尺度，开发和评估了基于两个学科和耦合界面的完善求解器的专用分区FSI模拟方法。主要成果有：1。涡流解析方法与薄壁柔性结构的鲁棒、高效、综合验证的耦合方法。2. 应用IGA和精确耦合层ECL，极大地改进了几何和运动学建模（目前用于非修剪NURBS表面）。3. 新开发的耦合软件EMPIRE在nurbs几何建模中的应用。4. 新FSI模拟方法首次应用于膨胀膜结构。在续文中，最终目标被追求：在流体方面，涡流解析方案和直接连接的FSI耦合算法必须在两个方面得到进一步发展：关于数值/方法问题，必须开发适当的网格变形算法，该算法允许将界面处表面网格的新获得的高网格质量转移到CFD体积网格。然而，考虑到额外的计算工作量和耦合les - fsi方法的特殊要求是决定性的。关于物理/方法问题，迫切需要对湍流流入条件的现实描述。然而，由于轻型结构主要是由偶尔出现的强风荷载，因此将开发一种考虑这种高动态荷载情景的湍流流入发生器。在结构方面，主要重点在于进一步系统地发展由CAD生成的裁剪多斑块几何图形的实际相关案例的斑块和表面耦合方法。目标是提供一个合适的几何和运动学公式，该公式在裁剪补丁和补丁界面（裁剪，非裁剪等）上也具有合适的几何表面特性，并满足非常精细的LES网格的高分辨率要求。进一步发展了两种策略：(1)fvm -求解器与等几何结构模型的直接表面耦合；(2)使用ECL作为中介层与具有较低连续性的任意结构模型（如经典有限元模型）的耦合。基于这一完整的方法，将考虑实际的柔性结构在湍流气流（包括强阵风）下的详细模拟和分析。

The objective of the project is to develop an optimized methodology for the simulation of transient fluid-structure interactions oflightweight flexible structures in turbulent wind flow. For the design of lightweight structures, the strong interaction with the turbulenthighly vortical flow is crucial. In the first period a dedicated partitioned FSI simulation methodology based on well establishedsolvers for both disciplines and a coupling interface was developed and evaluated, taking the specific properties and the characteristic scales of both fields into account. The main achievements are:1. Robust, efficient and comprehensively validated coupling method between eddy-resolving methods (LES) and thin-walled flexiblestructures. 2. Strongly improved modeling of the geometry and the kinematics (presently for non-trimmed NURBS surfaces) applying IGA andan exact coupling layer ECL. 3. Application of the newly developed coupling software EMPIRE for a NURBS-based geometry modeling. 4. First application of the new FSI simulation methodology to an inflated membrane structure. In the continuation the final goal is pursued:On the fluid side the eddy-resolving scheme and the directly connected FSI coupling algorithm has to be developed further in two regards: With respect to numerical/methodical issues an appropriate grid deformation algorithm has to be developed, which allows to transfer the newly achieved high grid quality of the surface mesh at the interface to the CFD volume grid. However, it is decisive to take distinctly the additional computational effort into account and to also consider the special requirements of the coupled LES-FSImethodology. With respect to physical/methodical issues a realistic description of the turbulent inflow conditions is urgentlyrequired. However, since lightweight structures are mainly loaded by sporadically appearing strong wind gusts, a turbulence inflowgenerator will be developed which takes this highly dynamic load scenario into account.On the structural side the main focus lies on the further methodical developments of the patch and surface coupling methods forpractically relevant cases of trimmed multi-patch geometries generated by CAD. The goal is to provide an appropriate geometric and kinematic formulation which possesses suitable geometric surface properties also on trimmed patches and at patch interfaces (trimmed, non-trimmed, etc.) and fulfill the requirements of the high resolution of the very fine LES grids. Two strategies are further developed: (1) A direct surface coupling of the FVM-solver with the isogeometric structural model and (2) a coupling to arbitrary structural models such as classical FEM possessing lower continuity properties using ECL as a mediator layer.Based on this entire methodology, detailed simulations and analyses of realistic flexible structures exposed to turbulent wind flows including strong gusts will be considered.