Tue January 7th 2014
16:00
HR Z203
Seminar Quasi-2D dynamic jamming of cornstarch suspensions
Ivo Peters

Details:

A dense suspension of cornstarch in water has the extraordinary behavior that, when perturbed lightly, it behaves like a liquid, but, when impacted at high velocities, the material solidifies. Waitukaitis et al. (Nature, 2012) have shown that this behavior is due to a dynamic jamming front that propagates through the system. The details of this jamming front, however, are obscured by the surrounding suspension in a 3-dimensional system. In our current experiment, we prepare a layer (thickness order 1 cm) of the cornstarch suspension, which floats on a dense liquid. We perturb the system by impacting an object horizontally on one side at a controlled velocity using a linear actuator. Tracer particles sitting on the top surface of the suspension allow us to perform PIV on the perturbed suspension. From the PIV analysis we determine the shape of the jammed region, the growth rate, shear rates, and the expected force response due to the added mass. We compare this to direct force measurements and determine which components make up the total force response.
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