O'Reilly logo

Aeroacoustics of Low Mach Number Flows by William Devenport, Stewart Glegg

Stay ahead with the world's most comprehensive technology and business learning platform.

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, tutorials, and more.

Start Free Trial

No credit card required

5

The Ffowcs Williams and Hawkings equation

Abstract

Lighthills acoustic analogy gives the general solution to the wave equation for a medium that includes turbulence and stationary scattering objects. In many important applications, such as for propellers and helicopter rotor noise, the surfaces are moving and so we need to modify the analysis to take full account of surface motion. Very powerful techniques to address this problem have been pioneered by Ffowcs Williams and Farassat, and the objective of this chapter is to introduce these techniques. We will start by reviewing the concept of a generalized derivative and then show how these may be used to give solutions to Lighthill's equation for a medium that includes moving surfaces and ...

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, interactive tutorials, and more.

Start Free Trial

No credit card required