Generalized Fluid System Simulation Program (GFSSP) version 4 is a generalpurpose computer program for analyzing steady-state and transient flows in a complex fluid network. [GFSSP version 2.01 was reported in a prior issue of NASA Tech Briefs.] The program is capable of modeling compressibility, fluid transients (e.g., water hammers), phase changes, mixtures of chemical species, and such externally applied body forces as gravitational and centrifugal ones. A graphical user interface enables the user to interactively develop a simulation of a fluid network consisting of nodes and branches. The user can also run the simulation and view the results in the interface. The system of equations for conservation of mass, energy, chemical species, and momentum is solved numerically by a combination of the Newton-Raphson and successive-substitution methods. The program includes subroutines that compute thermodynamic and thermophysical properties for 12 fluids and is integrated with a commercial program that gives thermodynamic properties of 36 fluids. Eighteen different options are provided for modeling momentum sources or sinks in the branches. Additional capabilities, including new resistance options, new fluids, and non-linear boundary conditions, can be added by means of subroutines. An audio-visual training CD (compact disk) containing lectures, demonstration of graphical user interface, and tutorial problems is available for learning to use the program.

This program was written by Alok Kumar Majumdar of Marshall Space Flight Center. For further information, access the Technical Support Package (TSP) free on-line at under the Software category.

This invention is owned by NASA, and a patent application has been filed. For further information, contact Sammy Nabors, MSFC Commercialization Assistance Lead, at This email address is being protected from spambots. You need JavaScript enabled to view it.. Refer to MFS- 32125-1.