http://yetl.yabesh.ir/yetl1/handle/yetl/19050 2026-09-14T14:32:18Z 2026-09-14T14:32:18Z Wang, Jin-Jun Wang, Jiang-Sheng http://yetl.yabesh.ir/yetl1/handle/yetl/4315957 2026-08-23T08:01:10Z 2026-01-01T00:00:00Z

Wake Vortices and Boundary Layer Interaction Wang, Jin-Jun; Wang, Jiang-Sheng Abstract. The interaction between wake vortices from an upstream body and a downstream boundary layer is significant for both fundamental and practical aspects of fluid mechanics. An in-depth understanding of the underlying flow physics is crucial for numerous problems in aeronautics, architectonics, and energy related to the complex interferences between different bodies or apparatuses. The incoming wake vortices can generally be divided into streamwise, vertical, and spanwise vortices based on their axial directions relative to the coordinate system of downstream boundary layer. They interact with the downstream boundary layer in different ways. However, the spanwise wake vortex has more profound effects on the downstream boundary layer than the other two, because it simultaneously disturbs the whole span region of boundary layer. Therefore, the vortex dynamics of interaction between spanwise wake vortices and a downstream boundary layer is focused on in this review. The efforts of unveiling the flow physics related to this kind of interaction with different canonical configurations are reviewed as the geometrical complexity increases. The wake-triggered spanwise secondary vortices and the laminar-to-turbulent transition routine caused by their destabilization are highlighted in particular. The transition process characterized by the evolution of secondary vortices is distinct from that of a natural transition or a bypass transition induced by freestream turbulence and is commonly encountered in flows around complex geometries. Finally, areas that deserve more attention in future work are outlined and discussed.

2026-01-01T00:00:00Z Xie, Zhaoqian Bai, Dongjun Ma, Jianli Jing, Chengyu Lu, Ming http://yetl.yabesh.ir/yetl1/handle/yetl/4315956 2026-08-23T08:01:08Z 2026-01-01T00:00:00Z

Characterization of Bilayer Tissue Moduli and Thickness Via Eccentric Rotating Mass Dynamics Xie, Zhaoqian; Bai, Dongjun; Ma, Jianli; Jing, Chengyu; Lu, Ming Abstract. The peripheral tissues consist of skin and subcutaneous tissue. Their multilayered biomechanical properties serve as key health indicators and are crucial for clinical applications. Flexible electronics offer a promising approach for continuous in vivo monitoring of peripheral tissue biomechanics. However, these methods depend on complex dispersion analysis or extensive experimental data fitting, which limits their practicality. This study develops an analytical model based on an eccentric rotating mass (ERM) motor for direct and simultaneous measurement of the elastic moduli and thickness of the top skin layer of bilayer tissue. The analytical model used to evaluate tissue compliance involves three dimensionless parameters: the modulus ratio between the top and bottom layers, the normalized thickness of the top skin layer, and one parameter related to ERM. Both simulations and experiments confirm the model's accuracy, showing average errors of only 10% in the inverse characterization of bilayer moduli and thickness for representative bilayer tissue phantoms, paving the way for the development of flexible devices for in vivo tissue health monitoring.

2026-01-01T00:00:00Z Lu, Lu Leanza, Sophie Zhao, Ruike Renee http://yetl.yabesh.ir/yetl1/handle/yetl/4315955 2026-08-23T08:01:04Z 2026-01-01T00:00:00Z

Mechanical Instabilities: From Failure Mechanism to Functionality Lu, Lu; Leanza, Sophie; Zhao, Ruike Renee Abstract. Mechanical instabilities, phenomena in which solids and structures lose stability under external stimuli, were traditionally regarded as failure mechanisms but have recently been harnessed to design various functional structures and systems. Over the past century, significant progress has been made in both understanding the fundamental mechanisms behind mechanical instabilities and leveraging them for innovative functional applications. In this review, we classify mechanical instabilities into five categories based on their underlying failure mechanisms: buckling instability, snap-buckling instability, surface instability, buckling-driven delamination, and dynamic instability. First, a brief historical overview of research in this field is presented. Then, for each category of mechanical instabilities, we systematically introduce the underlying mechanisms and associated functional applications, with a particular focus on three fundamental aspects: the conditions under which instability is triggered, the evolution of the system after the onset of instability, and the strategies for exploiting these instabilities in functional design. Finally, we discuss several promising directions for future research. We expect that this review can help readers have a deeper understanding of mechanical instabilities and thereby inspire their broader application in advanced materials and structural systems.

2026-01-01T00:00:00Z Zou, Qitong Huang, Rui Mu, Xusheng Li, Yingjian Hu, Haiyan Liu, Haojie Zhao, Yonghui http://yetl.yabesh.ir/yetl1/handle/yetl/4315953 2026-08-23T08:00:58Z 2026-01-01T00:00:00Z

Breaking Through Flutter Barrier of Rigid-Elastic Coupling Aircraft Zou, Qitong; Huang, Rui; Mu, Xusheng; Li, Yingjian; Hu, Haiyan; Liu, Haojie; Zhao, Yonghui Abstract. Flying-wing aircraft with high-aspect ratios have received extensive attention due to their outstanding aerodynamic efficiency and stealth capabilities. This type of aircraft, however, may suffer from rigid-elastic coupling flutters, such as a body-freedom flutter, owing to the interaction among flight dynamics, structural dynamics, and aerodynamics. This paper surveys the advances in modeling and analysis methods, control strategies, and experimental validations related to those flutters and their active suppressions. The paper begins with the modeling approaches in different frames of reference for a rigid-elastic coupling aero-servo-elastic system to emphasize their roles and merits in describing rigid-elastic interactions. Then, it discusses the mechanism of a rigid-elastic coupling flutter, accounting for the coupling of flight dynamics and aeroelastic vibrations. Afterward, the paper presents a comparison among the control performances of typical active flutter suppression strategies to evaluate the capacity of enhancing aircraft stability and increasing flutter speed. The paper also reviews the wind-tunnel tests and flight tests to verify the active flutter suppression techniques. Unlike other tests, the flight tests of the aeroelastic flight demonstrator (AFD) made by the authors indicate that the active controller could successfully remove the rigid-elastic coupling flutter and greatly increase the flutter speed till the occurrence of a bending-torsion flutter of higher order. Finally, the paper outlines future studies on flying-wing aircraft and active flutter suppression techniques.

2026-01-01T00:00:00Z