Gerris is a system for the solution of the partial differential equations describing fluid flow.

A brief summary of its main (current) features:

* Solves the time-dependent incompressible variable-density Euler,
Stokes or Navier-Stokes equations
* Adaptive mesh refinement: the resolution is adapted dynamically to
the features of the flow
* Entirely automatic mesh generation in complex geometries
* Second-order in space and time
* Unlimited number of advected/diffused passive tracers
* Flexible specification of additional source terms
* Portable parallel support using the MPI library
* Volume of Fluid advection scheme for interfacial flows
This package has MPI support built in.