Hydraulic and pneumatic networks are highly nonlinear and difficult to analyze. This study presents a software application designed to help students, visualize and understand fluid systems' dynamic behaviors. The application uses a combined bond graph and singular perturbation approach for system equation formulation. A standard iterative and adaptive integrator provides online numerical solutions to the system equations. Coupled to the integrator's output are a graphical animation subsystem and an instrumentation subsystem. The animation subsystem is responsible for rendering movable components on screen, at every simulation time-step, creating the illusion of continuous movement. The instrumentation subsystem collects and displays numerical data in numerical and graphical forms. An interesting contribution of this fluid system analyzer is its "user-in-the-loop" feature. This feature allows students to become active participants by enabling them to interact with network components while a simulation run is in progress. © 2005 Wiley Periodicals, Inc. Comput Appl Eng Educ 13: 169–180, 2005; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.20037

Hydraulic and pneumatic systems are highly nonlinear and difficult to analyze. This paper presents a quasi real-time simulator designed for efficient numerical simulation of hydraulic and pneumatic systems. This simulator uses a bond-graph theoretic approach for system equation formulation. A highly optimized and stabilized iterative integrator ensures accurate numerical solution of the system equations. Coupled to the integrator's output is a graphical animation subsystem. The latter is responsible for rendering movable components on screen at every simulation time-step. Thus, creating the illusion of continuous movement. An important characteristic of this simulator is its ability to permit in-simulation manipulation that allows user to interact with circuit components while a simulation run is in progress.