This video lesson describes how diffusers used in wind tunnels can reduce the inlet pressure required for Mach 2.5 flow from 17 atm to 2.4 atm. This reduction greatly reduces the cost and efficiency of wind tunnel equipment. This lesson is part of the Ansys Innovation Course: Internal Compressible Flows. To access this and all of our free, online courses — featuring additional videos, quizzes and handouts — visit Ansys Innovation Courses at https://www.ansys.com/courses.