Dynamically forced cells of a viscoelastic fluid over an array of rollers

Our fluid dynamics video shows the response of a layer of viscoelastic fluid to an array of four-roll mills steadily rotating underneath. When the relaxation time of the fluid is sufficiently long, the fluid divides into "cells" with a convex free surface above the site of each roller. This is reminiscent of the rod-climbing effect. On this relaxation time-scale, the flow also transitions from being initially Newtonian-like to one where the fluids' elasticity plays a dynamical role: The fluid cells oscillate with regularity in position and shape on a timescale much longer than the relaxation time. As the relaxation time is further increased, the cells become less localized to the underlying rollers, and their now irregular oscillations reflect the presence of many frequencies

Surface Waves on a Semi-toroidal Water Ring

We study the dynamics of surface waves on a semi-toroidal ring of water that is excited by vertical vibration. We create this specific fluid volume by patterning a glass plate with a hydrophobic coating, which confines the fluid to a precise geometric region. To excite the system, the supporting plate is vibrated up and down, thus accelerating and decelerating the fluid ring along its toroidal axis. When the driving acceleration is sufficiently high, the surface develops a standing wave, and at yet larger accelerations, a traveling wave emerges. We also explore frequency dependencies and other geometric shapes of confinement

Heavy flags undergo spontaneous oscillations in flowing water

International audienceBy immersing a compliant yet self-supporting sheet into flowing water, we study a heavy, streamlined, and elastic body interacting with a fluid. We find that above a critical flow velocity a sheet aligned with the flow begins to flap with a Strouhal frequency consistent with animal locomotion. This transition is subcritical. Our results agree qualitatively with a simple fluid dynamical model that predicts linear instability at a critical flow speed. Both experiment and theory emphasize the importance of body inertia in overcoming the stabilizing effects of finite rigidity and fluid drag

Policy Brief No. 18 - The Dynamics of Inequality among Canadian Children

This study characterizes income inequality and mobility of Canadian children between the ages of 4/5 and 14/15. There is considerable inequality of family income. Moreover, income position is especially persistent for children at the bottom and top of the distribution; this is unfair and may be perpetuated into adulthood. Finally, family structure is very important for children’s material well-being; for example, they experience a considerable drop in income position upon parental separation/ divorce. It is recommended that such children be protected, perhaps through advance maintenance payments

Dynamics of a deformable body in a fast flowing soap film

We study the behavior of an elastic loop embedded in a flowing soap film. This deformable loop is wetted into the film and is held fixed at a single point against the oncoming flow. We interpret this system as a two-dimensional flexible body interacting in a two-dimensional flow. This coupled fluid-structure system shows bistability, with both stationary and oscillatory states. In its stationary state, the loop remains essentially motionless and its wake is a von K\'arm\'an vortex street. In its oscillatory state, the loop sheds two vortex dipoles, or more complicated vortical structures, within each oscillation period. We find that the oscillation frequency of the loop is linearly proportional to the flow velocity, and that the measured Strouhal numbers can be separated based on wake structure

Music After The Cultural Revolution: Transnational Precarity For China\u27s One-Child Generation

This dissertation studies the intergenerational effects of the Chinese Cultural Revolution and the transnational careers of Chinese musicians born and raised during the one-child policy. Bridging scholarship in ethnomusicology and musicology with work in cultural anthropology, East Asian studies, Asian American studies, and literature studies, I examine the palpable memories and traumas from the Cultural Revolution and show that they continually frame individual and collective engagements with music in the People’s Republic of China and the Chinese diaspora. At the core of this research are extensive multi-sited ethnography conducted in the PRC, Taiwan, Canada, and the United States, and archival sources. Using these interdisciplinary methodologies, I address Chinese music-making practices in relation to personal and familial desires, and national transformations. I argue that although some Chinese musicians have achieved the highest levels of institutional success through conservatory training and international performances, they are continually motivated by anxieties of socio-economic precarity and desires for redress from parents who lost musical ambitions during the Cultural Revolution. As a result, Chinese musicians use what I term “strategic citizenship” to create transnational opportunities and seek stable futures for themselves while navigating neoliberal systems that impact their educational pathways and possibilities for new residency in countries such as Canada and the United States