Ethirajan Rathakrishnan is a Professor of Aerospace Engineering at the Indian Institute of Technology Kanpur, India. He is internationally recognized for his research in high-speed jets, including the establishment of the Rathakrishnan Limit for passive control of jets. His contributions to aerospace engineering include the development of the Breathing Blunt Nose (BBN) concept for drag reduction at hypersonic speeds and significant advances in vortex flow theory by positioning the twin-vortex Reynolds number at around 5000 using flat plate geometry. A Fellow of the Royal Aeronautical Society and other professional societies, Professor Rathakrishnan has published extensively in reputed international journals. He is the author of several acclaimed books published by CRC Press, including Encyclopedia of Fluid Mechanics (9781032382388), Elements of Heat Transfer , 2nd ed. (9781041236788), and Instrumentation, Measurements, and Experiments in Fluids, 3rd ed. (9781041345169).