User:Arcturus0624/Eulerian fluid dynamics

The Eulerian and Lagrangian viewpoints are two different ways to represent a fluid flow. In Lagrangian fluid mechanics, the fluid properties and equations are written for a fixed parcel of fluid. In Eulerian fluid mechanics, fluid properties and equations are written for a point in space. The two viewpoints are linked by the Material derivative, which gives the time derivative of a variable for a fixed fluid particle in an Eulerian frame of reference. Most fluid flow analyses, including numerical simulations, are based on the Eulerian viewpoint; equations can be written more easily in a reference frame with a well-defined (or no) motion. A notable exception is the simulation of multiphase flows, in which the dispersed phase (bubbles, droplets, or particles) is simulated as discrete parcels in a Lagrangian frame of reference while the continuous phase is simulated in an Eulerian frame of reference.