Research Group of Prof. Dr. M. Griebel
Institute for Numerical Simulation


A Parallel 3D Free Surface Flow Solver




NaSt3DGPF is an implementation of a solver for the incompressible Navier-Stokes equations in three dimensions. It allows the realistic simulation of two-phase flows with free surfaces. NaSt3DGPF exhibits the following features:
  • Simulation of two-phase flow is implemented with a level-set approach
  • Surface tension forces are implemented with the continuum surface force method
  • Simulation of turbulence is based on a large-eddy approach (Smagorinsky model)
  • Convective terms can be discretized with higher order ENO and WENO schemes
  • spatial discretization by 2nd order finite differences on a rectangular, non-uniform, staggered mesh
  • convective term: higher order upwind schemes (VONOS, SMART), central differences (2nd order), simple upwind (1st order)
  • 2nd order Adams-Bashforth scheme for the time discretization
  • boundary conditions: slip, no slip, periodic, inflow, outflow (Neumann, convective, natural)
  • (passive) advection-diffusion transport model for concentration of species
  • Boussinesq advection-diffusion transport model for temperature
  • handling of complex geometries by a simple cell decomposition/enumeration technique
  • BiCGStab and SOR iterative solver for pressure Poisson equation (lexicographical, red-black, colored red-black)
  • parallelization by means of 3D domain decomposition with good communication/work ratio heuristics
  • parallelization based on MPI
  • implemented in C++
  • various import/export formats, including architecture independent ones and for the VTK graphics library
  • macro language for easy problem description
Much emphasis is laid on the point that also complex problems, such as flows around complicated geometries, can be defined in a clear and easy way to obtain numerical results rapidly. To this end, there is a simple macro-language with a few but powerful and meaningful key-words to describe the flow configuration. This allows the user to
  • build complex geometries by union, intersection, subtraction of CSG (Constructive Solid Geometry) primitives using shape parameters independent on the discretization
  • describe the computational mesh in a simple way
  • define various parameters, e.g. Reynolds number, stopping value for iterative solver, upwind parameter, etc.
Have a look at the Gallery for movies of simulation results obtained with NaSt3DGPF.
A list of projects which use NaSt3DGPF as the primary toolkit for numerical simulation of two-phase flow is available here.


The software package NaSt3DGPF can be licensed on an individual basis. Please contact us for further details.


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