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.