lagrangian/eulerian views
 

Hello, a simple question about the Lagrangian and Eulerian descriptions of fluid flow.

When is the Lagrangian (particle point of view) useful? It seems that the Eulerian is always the right one, since velocity and pressure are fields.....

thanks ! marco

Re: lagrangian/eulerian views
 

Hi Marco. There is a competition between advective motions and diffusion in general fluid flows. When advection dominates the dynamics, a Lagrangian perspective can be useful. Lagrangian frames track the history of fluid elements. One practical application is: if you have an immersed elastic solid, the communication between the solid and fluid dynamics may be simplified if everything is done in a Lagrangian frame. More often than not, however, you will see problems being tackled in Eulerian frames, as there are various numerical difficulties that arise in Lagrangian frames when you have, say, diffusion.