Introduction

NaSt3DGP is a C++ implementation of a solver for the incompressible, time-dependent Navier-Stokes equations in three dimensions. It is based on a Chorin-type projection method and uses finite difference approximations for the spatial derivatives on non-uniform staggered meshes. Among the implemented features are Adams-Bashforth and Runge-Kutta methods for handling of the time derivatives and various upwind schemes like QUICK, SMART and VONOS for discretization of the convective terms. The calculation of temperature or concentration fields within the flow is also possible.

The code can be compiled to get a parallel version based on the message passing interface MPI, or to get a single processor version, which does not require any installation of MPI.

NaSt3DGP provides a user-friendly interface to describe the geometry and the various problem dependent parameters by a macro language. This interface also provides import and export capabilities for the numerical results. In addition, NaSt3DGP includes some utilities for the generation of smooth non-uniform grids and for the import and export of numerical results from/to various other software packages such as MatLab or Tecplot.

The remainder of this guide is as follows.

Chapter 2 explains the installation of NaSt3DGP and the basic usage is shown for the standard testcase of Driven-Cavity flow.

Chapter 3 describes the numerical scheme. This includes the description of the difference stencils used for the spatial discretization and the boundary conditions.

Chapter 4 introduces navcalc and navcalcmpi - the parts of NaSt3DGP which actually perform the numerical simulations. A basic outline of the implementation is given. This should help users to adapt the code for their own purposes if necessary.

Chapter 5 deals with navsetup - the interface tool. First the command line arguments are introduced. navsetup is able to read so-called scene description files which describe different parameters of the flow, the spatial discretization and a description of the geometry of the domain using a simple macro language. The key words of this language are given in subsection .

Chapter 6 explains various utilities that come with NaSt3DGP.

Chapter 7 shows some example simulations done with NaSt3DGP. The scenefiles for these simulations are included in the distribution.

Chapter 8 describes how to report bugs.

Chapter 9 contains the license under which NaSt3DGP is made available.