Mechanics of Slender Biological Structures

细长的结构在我们的人造世界中无处不在：飞机机翼、水力涡轮机叶片或3D打印细丝都有比第三维大得多的一到两个维度。同样，自然界也充满了细长结构的例子：树枝和树叶、头发、蜘蛛丝或细胞膜等。我的研究重点是细长结构的力学，这个发现计划更具体地涉及生物细长结构的形态发生和流体-结构相互作用(FSI)。形态发生学描述生物细胞如何生长和分裂以塑造器官和有机体，即形状和结构是如何起源的。无论是作为内部载荷还是外部刺激，机械力在形态发生中都起着核心作用。外力的一个主要来源是FSI。因此，它创建了一个影响FSI的形状和结构反馈环，FSI反过来影响形态发生。具体地说，本探索计划解决以下问题。海藻是如何生长以达到各种形状的呢？他们的水动力环境如何影响他们的成长？植物是如何生长的？它们只是在压力下像气球一样膨胀细胞，还是也会膨胀细胞壁？为什么树木在风中弯曲以减少它们的阻力，而不像旗帜一样飘扬？振荡是否允许草捕获更多由风传播的花粉？同样，摆动是否允许软珊瑚捕获更多由水流携带的食物颗粒？我的方法结合了理论模型、理想化系统的桌面实验，以及在与生物学家紧密合作的框架下获得的对自然系统的观察。从长远来看，回答上述问题对于优化海藻水产养殖、农业、林业和水文学以最大限度地提高产量并将对环境的影响降至最低至关重要。基本知识将作为风对农作物和森林的破坏以及植被覆盖的运河和洪水淹没土地中的水流模型的基本成分。在气候变化和风暴更加频繁的背景下，这一知识将被证明比以往任何时候都更加重要。将应用工业研究和生物力学结合到一个实验室中，在思想杂交方面带来了巨大的协同效益。通过仿生，这一发现计划的研究将对自清洁疏水表面、用于组织工程的具有高表面积的分级3D打印长丝、高韧性微结构纤维、或用于层流条件的振荡增强型热交换器等的开发产生直接影响。

Slender structures are ubiquitous in our man-made world: aircraft wings, hydraulic turbine blades, or 3D printing filaments all have one or two dimensions much larger than the third one. Similarly, the natural world is also filled with examples of slender structures: tree branches and leaves, hairs, spider silk, or cellular membranes, etc. My research focuses on the mechanics of slender structures, and this Discovery Program more specifically concerns the morphogenesis and Fluid-Structure Interactions (FSI) of biological slender structures. Morphogenesis describes how biological cells grow and divide to shape organs and organism, i.e., how shape and structure originates. Mechanical forces play a central role in morphogenesis either as internal loads or external stimuli. One predominant source of external forces is FSI. It thus creates a feedback loop of shape and structure influencing FSI, and FSI affecting morphogenesis in return. Specifically, this Discovery Program addresses the following questions. How do seaweeds grow to achieve their variety of shapes? How does their hydrodynamic environment influence their growth? How do plants grow? Do they only inflate their cells like balloons under pressure or do they also swell their cell walls? How come trees bend under the wind to reduce their drag but do not flutter like flags? Does oscillating allow grasses to capture more wind-borne pollen? Similarly, does oscillating allow soft corals to capture more water current-borne food particles? My approach combines theoretical models, table-top experiments of idealised systems, and observations on natural systems obtained in a framework of tight collaboration with biologists. Over the long term, answering the questions above is crucial to optimise seaweed aquaculture, agriculture, forestry, and hydrology to maximise output and minimise our impact on the environment. The fundamental knowledge will serve as the base ingredients for models of wind damages to crops and forests, and water flow in vegetated canals and flooded land. This knowledge will prove ever more important in the context of changing climate and more frequent storms. Combining both applied industrial research and biomechanics into one lab brings in enormous benefits of synergy in terms of cross-breeding of ideas. Through biomimetic, the research in this discovery program will have an immediate impact on the development of self-cleaning hydrophobic surfaces, hierarchical 3D printed filaments with high surface area for tissue engineering, high toughness micro-structured fibers, or oscillation-enhanced heat exchangers for laminar flow conditions, etc.