Krishan Kumar Ahuja: A brief history and testimonial to the half century of achievements in acoustics.

This paper provides some personal background, technical achievements, and a few testimonials from those who Professor Krishan Kumar Ahuja has worked with throughout his career. I have known Krish as an advisor, a colleague, and as someone I would consider a friend since my graduate school enrollment at Georgia Tech. He not only supported my research in pursuit of an MS and PhD but has been a constant reliable source of technical and professional advice throughout my young career and today, over 30 years later. This paper contains contributions from Krish's wife Philippa, and from several students and colleagues. It has information from a small subset of many people that Krish has mentored and influenced and worked with over the years. It serves as a starting point for this special edition tribute to Dr Krish Ahuja and his half century of contributions in acoustics. Although Dr. Ahuja's contributions in jet noise are arguably his most foundational work, he has made significant technical contributions in the areas of cavity noise, engine acoustic liner technologies, rotorcraft and UAV noise, advanced flow and noise measurements and diagnostics, active flow and noise control, and many others. The subsequent papers to follow in this special edition cover a range of topics in areas exemplary to Dr. Ahuja's career and from authors he has worked with and influenced over the years. [ABSTRACT FROM AUTHOR]