Mon November 9th 2009
11:00
HR Z109
Seminar Dynamics, Instability, and Freezing of Metallic Foams
Anthony Anderson

Details:

A foam, which has gas bubbles crowding themselves in a liquid, will coarsen by the rupture of liquid bridges (lamellae) causing the coalescence of adjacent bubbles. In metallic foam, this type of coarsening is rapid. An aim in manufacturing processes is to devise protocols for freezing metallic foam into a strong, light-weight solid before the bubbles have combined. Local analysis based on long-wave approximations is used to study fluid flow, heat transfer, and solidification in individual lamellae as well as their instability.
Two problems will be presented in some detail. First, thin film dynamics are described in the immediate vicinity of a freezing front. Second, to characterize coarsening in the unfrozen regions of the foam, the spontaneous rupture of a thinning lamella from van der Waals instability is treated. As an outlook to future work, I will discuss how these local analyses can be incorporated into a network model of foam, suitable for instigating the macroscopic coarsening of metallic foams.
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