Woodruff School of Mechanical Engineering
Faculty Candidate Seminar
Vortex Dynamics of Bluff-Body Fluid-Structure Interactions
Ms. Jessica Shang
Princeton University, Mechanical and Aerospace Engineering
Thursday, February 12, 2015 at 11:00:00 AM
MRDC Building, Room 4211
Naturally-occurring structures such as wings, arteries, and plants are often very flexible and adapt to a wide range of flow conditions. Understanding how a flexible structure couples to its flow environment may present novel engineering insights and improve our understanding of many biological phenomena. First, I examine the vortex-induced vibrations (VIV) of a slender, flexible cantilevered cylinder at modest Reynolds numbers that typify biological flows, such as flow past sensory whiskers or plant stems. By decomposing the cylinder's structural oscillations into Euler-Bernoulli beam eigenmodes, I am able to show a discrete progression of the structural dynamics with increasing flow speeds and describe how the structural dynamics may predict the wake response. In particular, we observe a high-energy wake mode that has not been observed previously in free vibration, in conjunction with cooperating structural modes. The results reveal fundamental differences between this system and canonical VIV approximations of a two-dimensional cylinder with restricted movement. Second, we examine the effect of curvature on vortex shedding. Flow was parallel to the plane of curvature of rigid cylinders. A concave-facing cylinder with a small radius of curvature resists vortex shedding, forming a non-shedding wake along its length. As the Reynolds number is increased past a critical threshold, vortex shedding would occur. In contrast, a convex-facing cylinder would always shed. A mechanism is proposed for wake stabilization for the concave-facing cylinder.
Jessica Shang is a PhD candidate in the Department of Mechanical and Aerospace Engineering at Princeton University, working under the guidance of Lex Smits and Howard Stone. She received a BA in Engineering Sciences from Harvard, and conducted research on micro air vehicles in the Harvard Microrobotics Lab under Rob Wood. She then attended Cambridge on a Gates Cambridge Scholarship to earn an MPhil in Engineering, supervised by Holger Babinsky. At Princeton, she has been supported by a NSF Graduate Research Fellowship. Her primary research interests lie at the intersection of biology and fluid mechanics, particularly fluid-structure interactions.
Refreshments will be served.