Purpose

This paper aims to describe a research effort towards the comprehension of the unsteady phenomena due to the deployment of high-lift devices at approach/landing conditions.

Design/methodology/approach

The work starts from a preexisting platform based on an immersed boundary (IB) method whose capabilities are extended to study compressible and viscous flows around moving/deforming objects. A hybrid Lagrangian-Eulerian approach is designed to consider the motion of multiple bodies through a fixed Cartesian mesh. That is, the cells’ volumes do not move in space but rather they observe the solid walls crossing themselves. A dynamic discrete forcing makes use of a moving least-square procedure which has been validated by simulating well-known benchmarks available for rigid body motions. Partitioned fluid-structure interactions (FSI) strategies are explored to consider aeroelastic phenomena. A shared platform, between the aerodynamic and the structural solvers, fulfils the loads’ transfer and drives the sequence of the operating steps.

Findings

The first part of the results is devoted to a basic two-dimensional study aiming at evaluating the accuracy of the method when simple rigid motions are prescribed. Afterwards, the paper discusses the solution obtained when applying the dynamic IB method to the rigid deployment of a Krueger-flap. The final section discusses the aeroelastic behaviour of a three-element airfoil during its deployment phase. A loose FSI coupling is applied for estimating the possible loads’ downgrade.

Research limitations/implications

The IB surfaces are allowed to move less than one IB-cell size at each time-step de-facto restricting the Courant-Friedrichs-Lewy (CFL) based on the wall velocity to be smaller than unity. The violation of this constraint would impair the explicit character of the method.

Practical implications

The proposed method improves automation in FSI numerical analysis and relaxes the human expertise/effort for meshing the computational domain around complex three-dimensional geometries. The logical consequence is an overall speed-up of the simulation process.

Originality/value

The value of the paper consists in demonstrating the applicability of dynamic IB techniques for studying high-lift devices. In particular, the proposed Cartesian method does not want to compete with body-conforming ones whose accuracy remains generally superior. Rather, the merit of this research is to propose a fast and automatic simulation system as a viable alternative to classic multi-block structured, chimaera or unstructured tools.

中文翻译：

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使用动态浸入边界研究高升力装置的部署

目的

本文旨在描述一项旨在理解由于在进场/着陆条件下部署高升力装置而导致的不稳定现象的研究工作。

设计/方法/方法

这项工作从基于浸入边界 (IB) 方法的预先存在的平台开始，该方法的功能扩展到研究移动/变形物体周围的可压缩和粘性流。混合拉格朗日-欧拉方法旨在通过固定笛卡尔网格考虑多个物体的运动。也就是说，细胞的体积不会在空间中移动，而是观察穿过自己的实心墙。动态离散强迫使用移动最小二乘程序，该程序已通过模拟可用于刚体运动的众所周知的基准进行验证。探索了分区流固耦合 (FSI) 策略以考虑气动弹性现象。空气动力学和结构求解器之间的共享平台实现了载荷的传递并驱动了操作步骤的顺序。

发现

结果的第一部分致力于基本的二维研究，旨在评估在规定简单刚性运动时该方法的准确性。随后，本文讨论了将动态IB方法应用于克鲁格襟翼刚性部署时的解决方案。最后一部分讨论了三元件翼型在其展开阶段的气动弹性行为。应用松散的 FSI 耦合来估计可能的负载降级。

研究限制/影响

允许 IB 表面在每个时间步实际上移动小于 1 个 IB 单元大小，从而限制基于壁速度的 Courant-Friedrichs-Lewy (CFL) 小于 1。违反此约束将损害该方法的显式特性。

实际影响

所提出的方法提高了 FSI 数值分析的自动化程度，并减轻了人类在围绕复杂的三维几何图形对计算域进行网格划分的专业知识/工作。合乎逻辑的结果是模拟过程的整体加速。

原创性/价值

该论文的价值在于展示了动态 IB 技术在研究高升力装置方面的适用性。特别是，所提出的笛卡尔方法不想与准确度仍然普遍优越的符合身体的方法竞争。相反，这项研究的优点是提出了一个快速和自动的仿真系统，作为经典多块结构化、嵌合体或非结构化工具的可行替代方案。