With the advent of high-speed graphics workstations came the ability to develop Graphical User Interfaces (GUIs - pronounced gooies) allowing the user to interactively control the execution of a program while graphically displaying the program's results real-time. Such a capability provides a means for developing computational virtual-realities and methods for efficient exploration of complicated numerical problems. The examples shown below illustrate a few of the possibilities afforded by the use of GUIs.

Virtual Wind Tunnel: Experimentation in a wind tunnel is an invaluable component of every aerodynamisist's education. Unfortunately, many educational institutions do not have the resources to provide such an expensive and space-consuming facility. One solution is to provide students with a virtual wind-tunnel. Such a utility has been developed at the Naval Postgraduate School, as shown in the screen-shot at the right. The software provides a real-time, unsteady, potential-flow solution about a moving airfoil, and allows the user to probe the flow in much the same way that an experimentalist might make measurements in a real tunnel. Click the circle-i icon or the screen-shot to read more about this software.

Joukowski Airfoil Generator: Of course, virtual-realities are only one class of problem that may benefit from GUIs. Another highly successful application is the instructional benefit afforded by real-time feedback. An example of this is the Joukowski Airfoil Generator program pictured in the screenn-shot on the right. Without going into detail, the Joukowski airfoil problem uses a conformal-mapping technique to solve a very simple problem in one plane, and then map the solution into another plane where the result are of more interest. Specifically, the Joukowski transform maps circles in one plane into shapes that make pretty good airfoils in another plane. The size and location of the circle determines the thickness and camber of the airfoil. A really nice feature of the conformal mapping method is that the transformation is analytic, which basically means that we can also transform our governing equations from one plane to the other. Therefore, we can solve for the really simple flow around a cylinder in one plane, and map this solution into the other plane to give us the flow about an airfoil. The numerical algorithm is a common Computational Fluid Dynamics (CFD) exercise in undergraduate and graduate courses.

The problem with the non-GUI form of the program is that it is difficult for users to get a feel for the relationship between the circle and the airfoil, but with the instantaneous feedback of the GUI, it is immediately obvious. Click on the circle-i icon or the screen-shot for details on this code. A downloadable version of the software is available for SGI users.