Zur Theorie der Lichtstrahlen

Abstract

1 zv = tr, cos-22n +-D ' sin-9-z T T -* t (n? + ~' 2 + Oz + b'? + m' + m'l). setzt, 2 _ _ _ _~ -1) C l e b s c h in Borchard's Journ. 61. p. 195. 1562.

Surface Integral Analogy Approaches to Computing Noise Generated by a 3D High-Lift Wing Configuration

“…In the Kirchhoff method, the integral surface is assumed to be located in a position where the condition of the wave propagation is satisfied. 7 In practice, this means that the nonlinear quantities such as ρu i u j on the integral surface must be considerably weaker than the linear terms p ′ , dp/dn and dp/dt. 6 The surface is required to be large enough to enclose most of the strong nonlinear structures of the flow.…”

“…5,6 The Kirchhoff method is an alternative acoustic analogy of the surface integral. [7][8][9][10] The integral surface in this method should be located in the linear region of the flow where the wave propagation condition is fulfilled. Then it is necessary to enclose all nonlinear sound sources by the integral surface.…”

Aero-acoustic computations of wind turbines

“…This became a more generalized approach for noise prediction based on Lighthill's acoustic analogy. The Ffowcs Williams and Hawkings' integral approach has some resemblance with the Kirchhoff's theory [18] which was proposed in 1882. In Kirchhoff's theory the wave equation is represented by a surface integral and was originally applied for light diffraction and electromagnetic problems.…”

Am Rande des Unendlichen: Numerische Verfahren f�r unbegrenzte Gebiete

“…Randbedingung durch einen angenäherten Differentialoperator bietet die Kirchhoffsche Integraldarstellung der exakten Lösung [13]. Nach dem Huygens'schen Prinzip [11] [5], dessen Form und Position ja frei zur Wahl stehen.…”