Computer simulation of complex high speed fluid flow is a vital issue to the design of experimental space vehicles. During reentry from Earth's orbit, a spacecraft plows into relatively dense air at over 17,000 miles per hour. At this speed, the air surrounding the vehicle undergoes extreme compression and, as a result, heats to thousands of degrees. In fact, during the reentry phase of space flight, the air surrounding the vehicle must be regarded as a chemically reacting and radiating mixture of atoms, molecules, and ions. Manned space vehicles must survive reentry with 100 percent certainty and, in the case of modern space planes, descend afterwards to a runway in a manner similar to a conventional airplane. This challenging goal must be attained economically, both with respect to the size and complexity of the vehicle itself, and with respect to the cost of the vehicle's design and construction. Therefore, the space vehicle design team must be aided by numerical simulation.

Hypersonic flows are essentially impossible to model reliably in a wind tunnel. Moreover, wind tunnel experimentation is expensive for a given configuration and very difficult to apply to subtle design changes. Unfortunately, numerical simulation is also far from 100 percent reliable. What appear to be small changes in a given model for the physics can often lead to substantial changes in a computed solution. Moreover, one computed solution can vary from another one, given the same configuration, depending only on the particular numerical algorithm employed. For these reasons, it is desirable to compare numerical simulation to wind tunnel experimentation on certain standard test problems. Experimental techniques also vary from one research group to another. It is therefore of value to compare experimental results from many research groups applied to standardized test problems as well as various computer simulations applied to standard problems.

Figure 1a (l.). The Hyperboloid Flare test problem T2.1a from the 1995 Houston workshop.
Figure 1b (r.). The Shock-Shock Interaction test problem T3.1 from the 1995 Houston workshop.

During the late 80's and early 90's, the Europeans seriously considered constructing a manned space plane which was to be denoted the Hermes. While the Hermes project was recently canceled, some good things survived its demise. One example is the annual European workshop on "Hypersonic Flows for Reentry Problems" first held in Antibes, France in 1990. In 1995, this workshop was held for the first time in the USA at the University of Houston; see the web page http://math.uh.edu/~hsff. Numerous computational and related experimental data have been collected during these several workshops for a wide variety of test problems specifically focused on very high speed flight. These data are kept in the European High Velocity Database (EHVD) which is located at the Institut National de Research en Informatique (INRIA), Sofia-Antipolis, France. The current EHVD is really little more than an ftp site. The University of Houston and JSC have agreed to form a joint High Speed Flow Database with INRIA. We are in the process of developing some new key capabilities over the capabilities of the EHVD. One is interactive network flow visualization.

Figure 2. The energy field of a Navier-Stokes calculation around the US shutle. These results are from C.P. Li from NASA/JSC. The full solution can be visualized on the web at ../Sanders1.html.

A three dimensional fluid flow visualization project was initiated between R. Sanders of Houston and Thomas Niederle of the University Munich during Niederle's Aerospace Technology Diploma Thesis work done with Sanders in 1993. Over the last several months, Sanders and Eric Morano (ISSO 1996 post-doc) have extended this earlier work to include networking capabilities. Morano is an experienced computational fluid dynamics researcher, having done his Ph.D. work at INRIA, Sofia-Antipolis and two years at NASA/Langly before coming to UH. Demos of this work can be found at http://math.uh.edu/~~sanders/Sandersl.html as well as http:// math.uh.edu/ ~~eric/demo_2d.html. Summer support funding as well as funding to support a graduate student have come to this project from NASA. Moreover, a graduate student exchange program between UH and the University of Nice are in the early stages of discussion. (Nice is affiliated with INRIA at Sofia-Antipolis.) It is the desire of our two groups, the EHVD and Houston HSFD, to use this graduate student exchange to solidify our long term cooperation on this effort.

References
1Hypersonic Flows for Reentry Problems, I & II. Ed. Desideri, Glowinski and Periaux, Berlin: Springer 1991.
2"3D-Visualization of Computational Fluid Dynamics," Diploma Thesis, Technical University of Munich, 1993.
3High Speed Flow Fields. Ed. Desideri, Fitzgibbon, Glowinski and Periaux, Strasbourg: Wiley.