Dr. Joseph C. (Joe) Majdalani is the Auburn Alumni Engineering Council Endowed Professor and Chair of Aerospace Engineering at Auburn University. He previously served as Professor and H. H. Arnold Chair of Excellence in Advanced Propulsion at the University of Tennessee. He is known for his work on acoustic instability theory and vortex engine technology encompassing solid, liquid and hybrid rocket applications. Dr. Majdalani is presently a Fellow of ASME, Associate Fellow of AIAA, Vice-Chair of the AIAA Hybrid Rockets Technical Committee, Associate Editor of the International Journal of Energetic Materials and Chemical Propulsion (Begell House), and AIAA Instructor for two short courses. Dr. Majdalani’s research devotes itself to the theoretical and computational modeling of thermofluid and propulsion systems that are mainly driven by either wall-normal or wall-tangential injection. His interests span both low and high speed fluid mechanics, hydrodynamic and acoustic instabilities, engine internal flowfields, vorticity dynamics, biologically-inspired fractal flows, and singular perturbation theory. His research activities since 1997 have materialized in over 240 publications in first-rate journals, book chapters, and conference proceedings. His work on helical flow modeling has led to the discovery of new Trkalianand Beltramian families of solutions to describe cyclonic motions in self-cooled liquid and hybrid rocket engines, tropical cyclones, and industrial centrifuges. His work on wave propagation has resulted in the development of a generalized-scaling technique in perturbation theory, and of a consistently compressible framework for capturing both vorticoacoustic and biglobal stability waves in simulated combustors. Recently, his work on compressible gas motions has required the development of a systematic procedure for modeling high speed flow problems. In fact, a total of eighteen dimensionless parameters have been newly identified in the course of his research investigations.