A Code for Linear Stability Analysis

Abstract

Linear.x is a spectral code for the analysis of the linear stability of some basic state. The code is generic and void of any particular physical problem yet provides for various common tasks:

• global — eigenvalue spectra,

• local — single eigenvalues and eigenfunctions,

• table — one- or more-dimensional tables of eigenvalues

• curve — (neutral) curves in parameter space

and others. A specific physical problem can be defined in a set of usually very short files. Some of these files are included at compile time, while definitions, tasks, and parameters are read during run time. The code is written in Fortran 77. The standard version has been used in various Unix environments and under VAX-VMS. The code has been successfully used for a variety of classical stability problems and is currently utilized to analyze the stability of compressible flows.