昆蟲翅膀形變之慣性調控及飛行動力效應

科技的演進（如高速攝影術、流場可視化、及模型建立等）使世人得以探討昆蟲飛行的非穩態流體動力機制。昆蟲的翅膀具有複雜的結構，在飛行時產生顯著的形變，實驗與計算流體力學研究均指出，振翅中產生的形變與所產生的流體動力（如升力）息息相關。證據顯示形變是由兩種力所主控：翅膀的質量所產生的慣性力，以及其材料所造成的彈性恢復力。許多昆蟲翅膀上具有的翅痣結構，由於其無論對振翅關節或翅膀的扭轉中軸均貢獻相當的轉動慣量，無疑將影響翅膀振動及形變，然而至今翅痣對翅膀振動的效應卻尚未經由實驗證實，遑論其對翅膀形變、及昆蟲飛行的影響。本研究將結合運動學、材料力學、以及流體力學的實驗及分析技術，探討翅痣對翅膀形變的慣性調控效應，並研究此效應如何影響翅膀的空氣動力、以及昆蟲飛行。本計畫共有四個主要目標：（一）探討翅痣如何影響拍動翅膀的形變，（二）量測翅膀的彎曲特性，（三）量測翅膀的振動特性，以及（四）探討因翅痣所影響之翅膀形變在流體動力上的效應。我們也將探討生物如何主動調控翅膀形變。我們期待此跨領域之研究計畫，將激發物理、生物、及工程學家對昆蟲飛行的物理原理、演化適應、及微飛行器設計的研究靈感。Insects are known for their impressive flight capability. Recent development oftechnology (e.g. high-speed videography, modern flow visualization, computational andmechanical modeling, etc.) has advanced our understanding of the unsteady aerodynamicmechanisms of lift-enhancement in insect flight. Insects achieve remarkable flightperformance with a diverse range of complex wing designs. Empirical evidences indicatethat wing deformation occurred during flight has significant influence on generatedaerodynamic forces. It has been demonstrated that the dynamic deformation patterns ofwings are dominated by inertial and elastic processes, remaining largely independent of thepressure distribution resulting from aerodynamic forces. The elastic properties of insectwings have been tested to associate with lift generation; whereas the inertial load from thewing mass contributes to wing rotation and twisting, and thought to play a major role for thefeatures of stroke reversals. Here we propose the first study to examine the mechanicaleffects of an “inertial regulator” pterostigma (a structure located distally from the wing baseand torsion axis, with area density 10 X that the rest of the wing) in determining thedeformation and vibration characteristics of dragonfly wings and subsequently theaerodynamics of insect flight. This project has four specific aims:[1] Examining the effects of pterostigma on wing deformation in flapping motion;[2] Measuring wing's material properties: flexural stiffness under static loading;[3] Measuring wing's material properties: dynamic excitation and natural frequency;[4] Examining the aerodynamic effects of inertial regulated deformation.We hypothesize that (1) pterostigma can enhance deformation in a flapping wing andstabilize vibration in a gliding fixed wing, (2) animals can actively control wing deformation,even when the pterostigma is removed, by manipulating flapping amplitudes in order to keepsimilar wing deformation, and (3) pterostigma has significant effects on generatedaerodynamic forces through inertial regulation of wing deformation. To this end, we willintegrate various techniques to examine the wing kinematics and deformation in both isolatedand intact flapping wings in living dragonflies, to assess the natural frequency and othervibration characteristics of a flapping and gliding wings, to measure the mechanical propertiesof wings under bending loads, and to quantify and analyze the flow field caused by inertialregulated deformation. This project will foster new and exciting multi-disciplinarycollaborations between physicists who seek to explain the phenomenology of insect flight,biologists who seek to understand its relevance to insect physiology and evolution, andengineers who are inspired to build micro-robotic insects using these principles

生物嗅覺機制之流體動力學研究

嗅覺（偵測環境中的化學訊息）對動物生存具有舉足輕重的影響。雖然近年來對於嗅覺的生物與化學機制已有長足的瞭解，但對化學偵測的物理機制卻所知有限。這個事實也反映在人工生物感覺器（如電子鼻）的設計上，亦即其多著重在生物感覺機制的生化層面，但卻鮮少考量到其物理特質。為了進一步以物理與數學模擬生物的感覺系統、並在未來研發人工生物感覺器，當前必須得到足夠的生物實驗數據，並瞭解生物偵測化學訊息的物理原理。本計畫的目的為研究生物嗅器的流體動力學，以及流與嗅器構造之間的交互作用，以期瞭解（一）在水及空氣兩種截然不同介質中，嗅器的物理行為與化學偵測的物理原理，及（二）在變動的流體環境中，生物如何調節嗅器的偵測行為，以達到最佳的偵測結果。本計畫將以台灣的陸生及水生寄居蟹為模式系統，以數位質點影像測速系統來進行嗅器周圍流的可視化，及流場速度分析；並運用掃瞄式電子顯微鏡影像，來測量嗅器的超顯微結構形態，計算出嗅器進行化學偵測時的雷諾數，進而比較不同種生物間、不同介質間、以及不同流速間嗅器周圍的流動狀態，期能瞭解化學偵測的物理原理及生物嗅器是否運用最佳化的流場

Skeletal modification in response to flow during growth in colonies of the sea whip, Junceella fragilis

Sessile marine organisms depend on water motion for important physiological functions yet face dislodgement or breakage caused by hydrodynamic forces. During growth, these organisms are subjected to increasing bending moments as height increases and they may modify their mechanical supports accordingly. Here we used the sea whip Junceellafragilis as a model species to examine how sessile organisms modify their skeletal supports to cope with hydrodynamic forces during growth. Eighty-one colonies of J fragilis (height 5-156 cm) were collected from two populations in southern Taiwan. Within-colony variations in skeletal elements, namely the axial skeleton and sclerites, as well as the coenenchyme and water content were investigated by measurements taken from the base, middle, and top of colonies. The typological distribution of sclerites within colonies was examined in another 31 colonies. The results showed that the relative weight of axial skeleton increases while that of sclerites decreases with colony height, which suggests that the colony switches from using sclerites to axial skeleton as the main support system during growth. The axial skeleton at the colony base thickens in such a way as to maintain or slightly decrease its bending stress. A greater density of sclerites, mostly double-heads, found at the colony base also adds to the resistance to bending. Moreover, colonies living in environments with greater flows seem to incorporate more skeletal materials. This study demonstrates how sessile marine or2anisnis cope with increasing hydrodynamic forces during their life history by modifying the constitution and construction of their skeleton elements. (c) 2007 Elsevier B.V All rights reserved