We have studied the splashing dynamics of water drops impacting granular layers. Depending on the drop kinetic energy, various shapes are observed for the resulting craters. Experimental parameters that have been considered are : the size of the mill
imetric droplets; the height of the free fall, ranging from 1.5 cm to 100 cm; and the diameter of the grains. As the drop is impacting the granular layer, energy is dissipated and a splash of grain occurs. Meanwhile, surface tension, inertia and viscosity compete, leading to strong deformations of the drop which depend on the experimental conditions. Just after the drop enters into contact with the granular bed, imbibition takes place and increases the apparent viscosity of the fluid. The drop motion is stopped by this phenomenon. Images and fast-video recordings of the impacts allowed to find scaling laws for the crater morphology and size. This abstract is related to a fluid dynamics video for the APS DFD gallery of fluid motion 2010.
Faraday waves are generated at the air/liquid interface inside an array of square cells. As the free surface inside each cell is destabilizing due to the oscillations, the shape of the free surface is drastically changing. Depending on the value of t
he frequency f of oscillations, different patterns are observed inside each cell. For well defined f values, neighboring cells are observed to interact and a general organization is noticed. In such a situation, initially disordered structures lead to a general pattern covering the entire liquid pool and a spatial order appears all over the cell array. This abstract is related to a fluid dynamics video for the gallery of fluid motion 2009.
A negative bubble, coined antibubble, is composed by a thin air shell that is immersed in a soapy mixture. A large vortex is generated in the liquid using a mixer. An antibubble is then created close to the surface. The antibubble is fastly attracted
by the vortex. It rotates arount the core and comes closer and closer. When the stress is large enough, the vortex deforms the antibubble that winds around the eye vortex. The antibubble looks like a spiral. Under some conditions, the antibubble splits into several antibubbles that are ejected out of the eye vortex while the largest part is still trapped the vortex. This latter is elongated and is absorbed to the bottom of the tank before popping. fluid dynamics video
