IMOC is an Interactive implementation of
the Method Of Characteristics
for supersonic irrotational flow in a two-dimensional geometry.
As at Version 0.1.2, IMOC is a completely new implementation
of the Turbo-Pascal program described in the journal article:
Jacobs, P. A. & Gourlay, C. M. (1991),
An interactive method-of-characteristics program for gas-dynamic calculations.,
The International Journal of Applied Engineering Education, Vol.7(3),pp242--250.
The flow field is described as a mesh of nodes
with flow-field data known only at the nodes and
adjacent nodes being connected to each other along
the C-minus and C-plus characteristic directions.
For details on the method of characteristics as implemented
in IMOC, refer to a text on gas dynamics.
For an introductory discussion, try
J. D. Anderson, Modern Compressible Flow, McGraw-Hill;
for more detail on the axisymmetric formulation, try
H. Liepmann & A. Roshko, Elements of Gas Dynamics, Wiley;
and, for lots of detail, refer to
M. J. Zucrow & J. D. Hoffman, Gas Dynamics, Robert E. Krieger Publishing.
Since the geometry of the mesh evolves as the flow field is computed, it is often easier to decide what operation to perform next based on the state of the characteristic mesh. The IMOC software does the house-keeping and provides some basic computational functionality which can be used directly or can be augmented by user-written procedures.
The old MOC program was written as a single Pascal program and all interaction with the user occurred via its menu system. If a new feature was needed, the core of the program had to be edited and recompiled. In contrast, the new IMOC software consists of several layers:
For an introduction to the Tcl scripting language, see the URL http://dev.scriptics.com/scripting/primer.html. There are also a number of good books on the language and its graphics toolkit.