Michael Berhanu (University Paris Diderot) will give a seminar on Erosion patterns by dissolution.
Landscapes are shaped under water flows and wind action. Understanding their shape and evolution involves identifying the physical mechanisms at play. The processes of erosion of sediment composed of macroscopic grains have been extensively studied, which is not the case of the chemical erosion, the dissolution. Hydrodynamics controls often the erosion dynamics and modifies the shape of the dissolving interface, creating characteristic patterns. Here, we focus on the two cases, which we studied experimentally. First, when a soluble body is plunged into quiescent water, the dissolution itself induces solutal convection. The flow creates dissolution patterns, the initial scale of which is set by the solutal Rayleigh-Bénard instability. Secondly, we report the emergence of a streamwise dissolution pattern at the surface of an initially flat soluble material, inclined and subjected to a thin runoff water flow. Our observations may constitute the early stage of similar patterns observed in the field.