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Fluid Flow on and in Complex Media
In this talk, I will present experiments devoted to systems in which the couplings between the fluid and the surrounding medium lead to interesting flow dynamics. We will first consider the thin liquid films formed when jets impinge on solid surfaces such as hydraulic jumps and water bells. On a smooth surface, the flow is radial and isotropic. I will show how the addition of a controlled micro-patterned surface allows tuning of the geometry of the flow into polygonal water structures. The second part of the seminar will be devoted to confined flow. When a pressurized fluid is injected in an elastic matrix, the fluid generates a fracture that grows along a plane and adopts a fluid-filled disc-like shape. I will present experimental results on the dynamics of a fluid-driven crack in a gelatin matrix. Finally, I will present a study on suspension flow in microchannels. We use a microfluidic approach to study the formation of clogs due to the trapping of contaminants and the subsequent growth of the aggregate. These different studies illustrate that fluid-structure and fluid-particle interactions can contribute to complex flow behavior.