Animations Gallery

This animation shows the collapse of a loosely-packed column of sand  in water. The initial volume fraction is φ=0.554. The entire column is mobilized and the fiinal deposit assumes a trapezoidal shape.

This animation shows the growth of a 2D shear layer on a porous medium - pure fluid interface. Due to hydrodynamic instabilities, the shear layer grows unstable, lading to vortex formation and pairings. Eventually, only a pair of rollers is maintained through this pairing process.

This animation is the 3D equivalent of the previous simulation. After the vortex formation and initial pairings, the vorticity regularity breaks down. This signals the transition to turbulence.

This is an animation of a gravity-driven flow of a beach sand - water mixture on an inclined plane. The animation shows the evolution of the granular volume fraction and the onset of hydrodynamic instabilities on the interface between water- saturated beach sand and pure water.

Evolution of the volume fraction of a granular bulb under shear. The upper boundary is moving at a constant density, thus setting the heterogeneous mixture in motion. The granular bulbs deforms due to shear and the onset of the long wavelength Kelvin-Helmholtz instability.

This animation shows the evolution of temperature and fuel concentration during the ignition of a block of porous fuel by a hot stream of air. Once the hot stream reaches the porous fuel, it increases its temperature and a slow reaction (smoldering) begins. Eventually a thermal explosion takes place that marks the initiation of rapid burning of the porous block. 

Pyrolysis and shrinkage of a piece of wood placed in a stream of nitrogen. Due to the heating from the nitrogen stream, the liquid water inside the wood evaporates and the piece of wood shrinks. The quantities shown in this animation are: 1st Frame: water vapor and liquid water concentrations, 2nd Frame: cellulose and nitrogen concentrations, 3rd Frame: cellulose concentration and velocity amplitude.

This animation shows the temperature field during a Direct Numerical Simulation of turbulent thermal mixing of two water streams in a T-junction. The Reynolds number of the hot horizontal stream is 3000 and that of the cold incoming jet is 343. The temperature ratio between the two streams is 1.34.

Pressure field of a slightly overdriven unstable detonation. The animation shows the growth of instabilities and the formation of the detonation's cellular structure.

Pressure field of a 3D gaseous detonation. The triple lines of the leading shock move along the spanwise and cross-stream directions, thus forming an in-phase rectangular front structure.

Contour plots of the pressure field of a 3D simulation of detonation transmission from a small channel to a larger one. As the leading front expands to the larger channel it weakens, thus causing temporary quenching of the detonation. However, the transverse shocks provide further heating of the gaseous mixture which, in turn, ignites and re-establishes the detonation.

Contour plots of the fuel concentration during detonation transmission from a small channel to a larger one. In this case, and in contrast with the case above, the initial detonation is sufficiently strong to be transmitted immediately to the larger channel,  without temporary quenching. 

This animation depicts the ignition of a detonation via the reflection of an incoming converging shock wave. The quantity shown in this animation is the amplitude of the density gradient of the gaseous mixture (pseudo-schlieren image).