English: This .gif shows the output of a model of the initiation of termination of a Rayleigh–Taylor instability in 2D. This problem considers two immiscible fluids, implemented through the Shan–Chen model. The red fluid is initially located in a layer on top of the blue fluid, and feels the action of gravity. As a way of modeling a large density difference between the fluids, the blue fluid is assumed to be unaware of gravity. After some time, a Rayleigh–Taylor instability occurs, and the red fluid penetrates the blue one.