An active fluid is a densely packed soft material whose constituent elements can directly inject and dissipate energy.
[1] These materials come under the broad category of active matter and differ significantly in properties when compared to passive fluids,[4] which can be described using Navier-Stokes equation.
These materials have been shown to exhibit a variety of different phases ranging from well ordered patterns to chaotic states (see below).
Recent experimental investigations have suggested that the various dynamical phases exhibited by active fluids may have important technological applications.
[11] From topological considerations, it can be seen that the constituent element in quasi stationary states of active fluids should necessarily be vortices.