Laboratory Analogues
Laboratory experiments give us the opportunity to systematically investigate a range of flow conditions in a controlled environment at relatively low expense. My lab work has primarily focused on using bubble- and particle-bearing viscous suspensions to constrain the material properties and dynamics of multiphase lava flow analogues.
Dam-breaks
Working with bubble suspensions poses special challenges because bubbles are prone to breakage and escape and any measurement of suspension properties must average over a large number of bubbles and particles which requires relatively large experimental setups (order centimeters to tens of centimeters). Much of my lab work has utilized a dam-break setup in which a starting suspension is initially confined in a rectangular reservoir with a removable dam whose removal allows material to slump under its own weight down a confined channel. This geologically-relevant geometry allows for investigation of behavior at a range of strain rates simultaneously.
Suspension Rheology
I've worked on constraining three-phase rheology at bubble and particle volume fractions and strain rate conditions that scale to lava flows. Constitutive relationships that describe material properties as a function of a few, simple variables helps inform modeling efforts for hazard prediction.
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In this work, we achieved very high bubble volume fractions (up to 80%) and showed a strong stiffening effect of undeformed bubbles higher than predicted by previous theory and experiments.
Magnetic Resonance Imaging
A challenge of working with suspensions, whether they are laboratory analogues or natural lavas, is the opacity of the material limits observation to the flow exterior. To combat this issue, we teamed up with the Boyce Lab in Chemical Engineering at Columbia to use Nuclear Magnetic Resonance Imaging (MRI) to image flow interiors and directly measure the velocity of our liquid suspending phase. This allowed us to image internal flow structures including the development of shear bands.