Elimination of spurious eigenfrequency in the boundary element method using CHEEF technique

Abstract

It was found that the imaginary-part BEM for eigenproblems results in spurious eigensolutions. By adding the constraints from the null-field integral equation, the CHEEF method (Combined Helmholtz Exterior integral Equation Formulation) is proposed to eliminate spurious eigenfrequencies. The circular cavity is demonstrated to check the validity of the proposed method. 使用虛部核函數之邊界元素法來求解 Helmholtz 特徵值問題時，會有假根問題產生。為了解決假根問題，我們提出了一套 CHEEF 法來過濾假根。由於缺少實部的束制條件，可由零場外域積分方程取得額外的束制條件來補足不足的束制條件。本文以一個圓形的例子來驗證 CHEEF 法之可行性。