HIGH-TECH LABCOURSES
HIGH-TECH
LABCOURSES
Propagation of viscoplastic surges over complex topography
Viscoplastic, or yield-stress, fluids are involved in numerous geophysical and industrial processes. These materials can behave as either fluids or solids, depending on the applied loading. The development of accurate numerical models that can represent the propagation and deposition of free-surface viscoplastic surges is crucial for applications, but remains challenging due to the strong non-linearity of the rheology and the coexistence of fluid and solid zones in the flows. The objectives of this lab-course are to: (1) perform well-controlled laboratory experiments in which viscoplastic, gravity-driven surges are generated over a complex topography; and (2) compare the experimental results to the predictions of a hydraulic numerical model. Through this comparison, important assumptions concerning the treatment of the viscoplastic rheology in the numerical model will be tested.
PREREQUISITE
This lab course is well suited to M2 and PhD students with a background in fluid mechanics and / or materials science.
DESCRIPTION
Experimental study of gravity driven viscoplastic surges
The experiments will be performed in a dam-break configuration, using a model viscoplastic fluid (polymeric microgel). The rheological properties of the fluid will be measured independently with a laboratory rheometer. The basal topographies have been generated by 3D printing, to enable a precise comparison with the simulations. The propagation of the fluid and the final deposit will be monitored through an optical stereoscopy technique (fringe projection).
Numerical simulation and comparison of the results
Experiments will be simulated using a hydraulic numerical model based on a depth-averaged approach. This class of models requires a good knowledge of the internal dynamics of the flow (internal velocity profile, basal slip condition, etc.). The influence of the assumptions made in the model will be tested and discussed.
