User Guide Table of Contents

Gryphon
Euler Quasi One-Dimensional Euler Solver

Introduction: About the Code

    Gryphon is a Java-based computational fluid dynamics code written to solve the quasi 1-D Euler equations. Version 1 was written primarily in the summer and fall of 2002. Although most real fluid dynamics problems are two or three dimensional, solving the 1-D equations can be useful for several reasons. First, the code generates solutions very quickly, and can be useful to provide an initial approximation for common problems like nozzles and shocktubes. Moreover, the 1-D Euler equations are good for instructional and research purposes as they contain most of the difficult aspects of higher dimensional and/or viscous equation solution. It is often fruitful to test and evaluate new flux discretization schemes out on a code such as this to avoid the complications that higher dimesnions introduce (boundary condition treatment, grid construction, implicit solution sweeping/linearization, etc.).
    Gryphon offers many of the state-of-the-art techniques and features for solving this type of equation system. Several time integration schemes are supported with both explicit and implicit options. The most popular flux discretization scheme are coded, consisting of Roe flux difference splitting (the approximate Riemann problem) with a Harten entropy correction, Van Leer flux splitting, and AUSM flux splitting. Several popular choices of limiters are offered to suppress numerical oscillations of high order schemes associated with shocks. Steady-state and transient problems are available with comprehensive solution management. Local time stepping is available for steady problems which can sometime accelerate solution convergence speed. Simple, complete graphing routines are available coupled with solution export routines to ASCII text files for import into other programs.
    Additional advanced features are planned in a future version, which will include multi-grid acceleration, grid motion/optimization routines, and a viscous correction option for nozzles and similar applications.

Table of Contents:

Table of Contents
General Program Operation
Building a Physical Model
Generating a Grid
Setting Boundary Conditions
Setting Initial Conditions
Solution Options
Solution Control
Graphing Options
Evaluating the Solution
Tutorials

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