The solution of the pressure and flow rate components is substituted into the variational principle, a linear algebraic equation about the generalized coordinates is solved by an eigenfunctionexpansion method, and, in such a case, differentiation about the axial direction coordinates of the eigenvalue which arises because pipe cross sectional dimensions are not uniform in the axial direction is taken into consideration (step S4). 圧力と流速成分の解を変分原理に代入し、固有関数展開法により一般化座標に関する線形代数方程式を解き、この際、パイプ断面寸法が軸方向に一様でないために生じる固有値の軸方向座標に関する微分を考慮する(ステップS4)。 - 特許庁