This paper describes a computer modeling and simulation systemthat supports computational steering, which is an effort to makethe typical simulation workflow more efficient. Our system providesan interface that allows scientists to perform all of the stepsin the simulation process in parallel and online. It uses a standardnetwork flow visualization package, which has been extended todisplay graphical output in an immersive virtual environment suchas a CAVE. Our system allows scientists to interactively manipulatesimulation parameters and observe the results. It also supportsinverse steering, where the user specifies the desired simulationresult, and the system searches for the simulation parameters thatachieve this result. Taken together, these capabilities allow scientiststo more efficiently and effectively understand model behavior,as well as to search through simulation parameter space.This paper is also a case study of applying our system to theproblem of simulating microwave interactions with missile bodies.Because these interactions are difficult to study experimentally, andhave important effects on missile electronics, there is a strong desireto develop and validate simulation models of this phenomena.