Gas-solid flows are common in energy conversion processes like coal and biomass combustion. They also play a role in many environmental transport processes.
This image is a snapshot of the particle concentration field in a gas-solid flow obtained from a two-dimensional finite volume simulation. Bright orange regions correspond to regions of high particle concentration, while regions in black correspond to regions with very low concentration. These complicated flow
structures arise naturally as a consequence of the instabilities
manifested by the equations of motion, which are equations that describe the behavior of a system as a function of time.