This video, taken in low light condition, shows the accelerated deformation of a complex fluid. The fluid motion is observed by adding reflecting particles in suspension.
The so-called Rayleigh-Bénard convection in a complex fluid is obtained by heating the inner walls and cooling the upper walls. Initially, the fluid is at rest, the regime is then conductive. When the temperature difference between the two walls is sufficient, the gel starts moving and the regime becomes convective.
With this video, we characterize the fluid motion and we study the deformations, the rate of deformations and the stresses in the gel. The experimental work was achieved at « Laboratoire de Rhéologie et Procédés » (Grenoble) in the framework of M. Darbouli PhD with the collaboration of C. Métivier and A. Magnin.
Among the difficulties, the handling of the noise, which is very high and non-homogenous is challenging. Then comes the important variation of markers dimensions and their motion out of the focal plane.
The TRACK tools such as the filtering permitted to obtain qualitative and quantitative data leading to the evaluation of the fluid deformation.