広告
・運動量収支式の離散化
x, y軸方向の無次元化した運動量収支式は次式となります。
\[
\phi_x=\frac{\partial V_x}{\partial\tau}
+V_x\frac{\partial V_x}{\partial X}
+V_y\frac{\partial V_x}{\partial Y}
-\frac{\partial\sigma^*_{xx}}{\partial X}
-\frac{\partial\sigma^*_{yx}}{\partial Y}
-g_x^*=0
\]
\[
\phi_y=\frac{\partial V_y}{\partial\tau}
+V_x\frac{\partial V_y}{\partial X}
+V_y\frac{\partial V_y}{\partial Y}
-\frac{\partial\sigma^*_{xy}}{\partial X}
-\frac{\partial\sigma^*_{yy}}{\partial Y}
-g_y^*=0
\]
内挿関数Niを重み関数に使用すると離散化式は次式となります。
\[
\int_V
\begin{bmatrix}N_1\\N_2\\N_3\end{bmatrix}
\phi_i\,dV
=
\int_V
\begin{bmatrix}0\\0\\0\end{bmatrix}dV
=
\begin{bmatrix}0\\0\\0\end{bmatrix}
\]
速度、圧力は、内挿関数Niを用いてそれぞれ次式で表されます。
\[
\begin{aligned}
V_x
&=N_1V_{x,1}+N_2V_{x,2}+N_3V_{x,3}\\[6pt]
&=\begin{bmatrix}N_1&N_2&N_3\end{bmatrix}
\begin{bmatrix}V_{x,1}\\V_{x,2}\\V_{x,3}\end{bmatrix}\\[6pt]
&=[N]\{V_x\}=0,\\[6pt]
V_y&=N_1V_{y,1}+N_2V_{y,2}+N_3V_{y,3}=0,\\[6pt]
P&=N_1P_{x,1}+N_2P_{x,2}+N_3P_{x,3}
\end{aligned}
\]
i軸方向の離散化式は、次式となります。
\[
\begin{aligned}
&\int_V
\begin{bmatrix}N_1\\N_2\\N_3\end{bmatrix}\phi_i\,dV\\[6pt]
&={}\int_S
\begin{bmatrix}N_1\\N_2\\N_3\end{bmatrix}
\left(
\frac{\partial V_i}{\partial\tau}
+V_x\frac{\partial V_i}{\partial X}
+V_y\frac{\partial V_i}{\partial Y}
-\frac{\partial\sigma^*_{xi}}{\partial X}
-\frac{\partial\sigma^*_{yi}}{\partial Y}
-g_i^*
\right)dS
\end{aligned}
\]
展開すると
\[
\begin{aligned}
&={}\int_S\begin{bmatrix}N_1\\N_2\\N_3\end{bmatrix}\frac{\partial V_i}{\partial\tau}dS
+V_x\int_S\begin{bmatrix}N_1\\N_2\\N_3\end{bmatrix}\frac{\partial V_i}{\partial X}dS
+V_y\int_S\begin{bmatrix}N_1\\N_2\\N_3\end{bmatrix}\frac{\partial V_i}{\partial Y}dS\\[6pt]
&-\int_S\begin{bmatrix}N_1\\N_2\\N_3\end{bmatrix}\frac{\partial\sigma^*_{xi}}{\partial X}dS
-\int_S\begin{bmatrix}N_1\\N_2\\N_3\end{bmatrix}\frac{\partial\sigma^*_{yi}}{\partial Y}dS\\[6pt]
&-\int_S\begin{bmatrix}N_1\\N_2\\N_3\end{bmatrix}g_i^*dS
\end{aligned}
\]
\[
\begin{aligned}
&={}\int_S[N]^T\frac{\partial V_i}{\partial\tau}dS
+V_x\int_S[N]^T\frac{\partial V_i}{\partial X}dS
+V_y\int_S[N]^T\frac{\partial V_i}{\partial Y}dS\\[6pt]
&-\int_S[N]^T\frac{\partial\sigma^*_{xi}}{\partial X}dS
-\int_S[N]^T\frac{\partial\sigma^*_{yi}}{\partial Y}dS\\[6pt]
&-\int_S[N]^Tg_i^*dS
\end{aligned}
\]
グリーン・ガウスの定理より
\[
\begin{aligned}
&={}\int_S[N]^T\frac{[N](\{V_i\}^{\tau+\Delta\tau}-\{V_i\}^{\tau})}{\Delta\tau}dS\\[6pt]
&+V_x\int_S[N]^T\frac{\partial[N]\{V_i\}}{\partial X}dS
+V_y\int_S[N]^T\frac{\partial[N]\{V_i\}}{\partial Y}dS\\[6pt]
&-\int_L[N]^T\sigma^*_{xi}n_xdL
+\int_S\left[\frac{\partial N}{\partial X}\right]^T\sigma^*_{xi}dS\\[6pt]
&-\int_L[N]^T\sigma^*_{yi}n_ydL
+\int_S\left[\frac{\partial N}{\partial Y}\right]^T\sigma^*_{yi}dS\\[6pt]
&-\int_S[N]^Tg_i^*dS
\end{aligned}
\]
界面に作用する応力をまとめると
\[
\begin{aligned}
&={}\int_S[N]^T[N]dS\frac{\{V_i\}^{\tau+\Delta\tau}-\{V_i\}^{\tau}}{\Delta\tau}\\[6pt]
&+V_x\int_S[N]^T\left[\frac{\partial N}{\partial X}\right]dS\{V_i\}
+V_y\int_S[N]^T\left[\frac{\partial N}{\partial Y}\right]dS\{V_i\}\\[6pt]
&+\int_S\left[\frac{\partial N}{\partial X}\right]^T\sigma^*_{xi}dS
+\int_S\left[\frac{\partial N}{\partial Y}\right]^T\sigma^*_{yi}dS\\[6pt]
&-\int_L[N]^T(\sigma^*_{xi}n_x+\sigma^*_{yi}n_y)dL\\[6pt]
&-\int_S[N]^Tg_i^*dS
\end{aligned}
\]
応力を展開して
\[
\begin{aligned}
&={}\int_S[N]^T[N]dS\frac{\{V_i\}^{\tau+\Delta\tau}-\{V_i\}^{\tau}}{\Delta\tau}\\[6pt]
&+V_x\int_S[N]^T\left[\frac{\partial N}{\partial X}\right]dS\{V_i\}
+V_y\int_S[N]^T\left[\frac{\partial N}{\partial Y}\right]dS\{V_i\}\\[6pt]
&+\int_S\left[\frac{\partial N}{\partial X}\right]^T
\left\{-\delta_{xi}P+\frac1{Re}\left(\frac{\partial V_i}{\partial X}+\frac{\partial V_x}{\partial X_i}\right)\right\}dS\\[6pt]
&+\int_S\left[\frac{\partial N}{\partial Y}\right]^T
\left\{-\delta_{yi}P+\frac1{Re}\left(\frac{\partial V_i}{\partial Y}+\frac{\partial V_y}{\partial X_i}\right)\right\}dS\\[6pt]
&-\frac{2K^*}{We}n_i\int_L[N]^TdL\\[6pt]
&-\int_S[N]^Tg_i^*dS
\end{aligned}
\]
\[
\begin{aligned}
&={}\int_S[N]^T[N]dS\frac{\{V_i\}^{\tau+\Delta\tau}-\{V_i\}^{\tau}}{\Delta\tau}\\[6pt]
&+V_x\int_S[N]^T\left[\frac{\partial N}{\partial X}\right]dS\{V_i\}
+V_y\int_S[N]^T\left[\frac{\partial N}{\partial Y}\right]dS\{V_i\}\\[6pt]
&+\int_S\left[\frac{\partial N}{\partial X}\right]^T
\left\{-\delta_{xi}P+\frac1{Re}\left(\frac{\partial V_i}{\partial X}+\frac{\partial V_x}{\partial X_i}\right)\right\}dS\\[6pt]
&+\int_S\left[\frac{\partial N}{\partial Y}\right]^T
\left\{-\delta_{yi}P+\frac1{Re}\left(\frac{\partial V_i}{\partial Y}+\frac{\partial V_y}{\partial X_i}\right)\right\}dS\\[6pt]
&+\frac{2K^*}{We}n_i\int_L[N]^TdL\\[6pt]
&-\int_S[N]^Tg_i^*dS
\end{aligned}
\]
項ごとに分解して
\[
\begin{aligned}
&={}\int_S[N]^T[N]dS\frac{\{V_i\}^{\tau+\Delta\tau}-\{V_i\}^{\tau}}{\Delta\tau}\\[6pt]
&+V_x\int_S[N]^T\left[\frac{\partial N}{\partial X}\right]dS\{V_i\}
+V_y\int_S[N]^T\left[\frac{\partial N}{\partial Y}\right]dS\{V_i\}\\[6pt]
&+\frac1{Re}\int_S\left[\frac{\partial N}{\partial X}\right]^T\frac{\partial V_i}{\partial X}dS
+\frac1{Re}\int_S\left[\frac{\partial N}{\partial X}\right]^T\frac{\partial V_x}{\partial X_i}dS
-\int_S\left[\frac{\partial N}{\partial X}\right]^T\delta_{xi}P\,dS\\[6pt]
&+\frac1{Re}\int_S\left[\frac{\partial N}{\partial Y}\right]^T\frac{\partial V_i}{\partial Y}dS
+\frac1{Re}\int_S\left[\frac{\partial N}{\partial Y}\right]^T\frac{\partial V_y}{\partial X_i}dS
-\int_S\left[\frac{\partial N}{\partial Y}\right]^T\delta_{yi}P\,dS\\[6pt]
&+\frac{2K^*}{We}n_i\int_L[N]^TdL\\[6pt]
&-g_i^*\int_S[N]^TdS
\end{aligned}
\]
速度、圧力を内挿関数で表示して
\[
\begin{aligned}
&={}\int_S[N]^T[N]dS\frac{\{V_i\}^{\tau+\Delta\tau}-\{V_i\}^{\tau}}{\Delta\tau}\\[6pt]
&+V_x\int_S[N]^T\left[\frac{\partial N}{\partial X}\right]dS\{V_i\}
+V_y\int_S[N]^T\left[\frac{\partial N}{\partial Y}\right]dS\{V_i\}\\[6pt]
&+\frac1{Re}\int_S\left[\frac{\partial N}{\partial X}\right]^T\frac{\partial[N]\{V_i\}}{\partial X}dS
+\frac1{Re}\int_S\left[\frac{\partial N}{\partial X}\right]^T\frac{\partial[N]\{V_x\}}{\partial X_i}dS
-\delta_{xi}\int_S\left[\frac{\partial N}{\partial X}\right]^T[N]\{P\}dS\\[6pt]
&+\frac1{Re}\int_S\left[\frac{\partial N}{\partial Y}\right]^T\frac{\partial[N]\{V_i\}}{\partial Y}dS
+\frac1{Re}\int_S\left[\frac{\partial N}{\partial Y}\right]^T\frac{\partial[N]\{V_y\}}{\partial X_i}dS
-\delta_{yi}\int_S\left[\frac{\partial N}{\partial Y}\right]^T[N]\{P\}dS\\[6pt]
&+\frac{2K^*}{We}n_iL\int_L[N]^TdL\\[6pt]
&-g_i^*\int_S[N]^TdS
\end{aligned}
\]
形状関数内挿後の節点自由度は積分変数に依存しないため、積分の外に出します。
\[
\begin{aligned}
&={}\int_S[N]^T[N]dS\frac{\{V_i\}^{\tau+\Delta\tau}-\{V_i\}^{\tau}}{\Delta\tau}\\[6pt]
&+V_x\int_S[N]^T\left[\frac{\partial N}{\partial X}\right]dS\{V_i\}
+V_y\int_S[N]^T\left[\frac{\partial N}{\partial Y}\right]dS\{V_i\}\\[6pt]
&+\frac1{Re}\int_S\left[\frac{\partial N}{\partial X}\right]^T\left[\frac{\partial N}{\partial X}\right]dS\{V_i\}
+\frac1{Re}\int_S\left[\frac{\partial N}{\partial X}\right]^T\left[\frac{\partial N}{\partial X_i}\right]dS\{V_x\}
-\delta_{xi}\int_S\left[\frac{\partial N}{\partial X}\right]^T[N]dS\{P\}\\[6pt]
&+\frac1{Re}\int_S\left[\frac{\partial N}{\partial Y}\right]^T\left[\frac{\partial N}{\partial Y}\right]dS\{V_i\}
+\frac1{Re}\int_S\left[\frac{\partial N}{\partial Y}\right]^T\left[\frac{\partial N}{\partial X_i}\right]dS\{V_y\}
-\delta_{yi}\int_S\left[\frac{\partial N}{\partial Y}\right]^T[N]dS\{P\}\\[6pt]
&+\frac{2K^*}{We}n_i\int_L[N]^TdL\\[6pt]
&-g_i^*\int_S[N]^TdS,
\qquad (i=1,2)
\end{aligned}
\]
行列式で表す
蓄積量
\[
=\int_S
\begin{bmatrix}
N_1N_1&N_1N_2&N_1N_3\\
N_2N_1&N_2N_2&N_2N_3\\
N_3N_1&N_3N_2&N_3N_3
\end{bmatrix}dS\,
\frac{\{V_i\}^{\tau+\Delta\tau}-\{V_i\}^{\tau}}{\Delta\tau}
\]
対流項
\[
\begin{aligned}
&+V_x\int_S
\begin{bmatrix}
N_1\frac{\partial N_1}{\partial X}&N_1\frac{\partial N_2}{\partial X}&N_1\frac{\partial N_3}{\partial X}\\
N_2\frac{\partial N_1}{\partial X}&N_2\frac{\partial N_2}{\partial X}&N_2\frac{\partial N_3}{\partial X}\\
N_3\frac{\partial N_1}{\partial X}&N_3\frac{\partial N_2}{\partial X}&N_3\frac{\partial N_3}{\partial X}
\end{bmatrix}dS\{V_i\}\\[6pt]
&+V_y\int_S
\begin{bmatrix}
N_1\frac{\partial N_1}{\partial Y}&N_1\frac{\partial N_2}{\partial Y}&N_1\frac{\partial N_3}{\partial Y}\\
N_2\frac{\partial N_1}{\partial Y}&N_2\frac{\partial N_2}{\partial Y}&N_2\frac{\partial N_3}{\partial Y}\\
N_3\frac{\partial N_1}{\partial Y}&N_3\frac{\partial N_2}{\partial Y}&N_3\frac{\partial N_3}{\partial Y}
\end{bmatrix}dS\{V_i\}
\end{aligned}
\]
粘性項のx成分/圧力項のx成分
\[
\begin{aligned}
&+\frac1{Re}\int_S
\begin{bmatrix}
\frac{\partial N_1}{\partial X}\frac{\partial N_1}{\partial X}&\frac{\partial N_1}{\partial X}\frac{\partial N_2}{\partial X}&\frac{\partial N_1}{\partial X}\frac{\partial N_3}{\partial X}\\
\frac{\partial N_2}{\partial X}\frac{\partial N_1}{\partial X}&\frac{\partial N_2}{\partial X}\frac{\partial N_2}{\partial X}&\frac{\partial N_2}{\partial X}\frac{\partial N_3}{\partial X}\\
\frac{\partial N_3}{\partial X}\frac{\partial N_1}{\partial X}&\frac{\partial N_3}{\partial X}\frac{\partial N_2}{\partial X}&\frac{\partial N_3}{\partial X}\frac{\partial N_3}{\partial X}
\end{bmatrix}dS\{V_i\}\\[6pt]
&+\frac1{Re}\int_S
\begin{bmatrix}
\frac{\partial N_1}{\partial X}\frac{\partial N_1}{\partial X_i}&\frac{\partial N_1}{\partial X}\frac{\partial N_2}{\partial X_i}&\frac{\partial N_1}{\partial X}\frac{\partial N_3}{\partial X_i}\\
\frac{\partial N_2}{\partial X}\frac{\partial N_1}{\partial X_i}&\frac{\partial N_2}{\partial X}\frac{\partial N_2}{\partial X_i}&\frac{\partial N_2}{\partial X}\frac{\partial N_3}{\partial X_i}\\
\frac{\partial N_3}{\partial X}\frac{\partial N_1}{\partial X_i}&\frac{\partial N_3}{\partial X}\frac{\partial N_2}{\partial X_i}&\frac{\partial N_3}{\partial X}\frac{\partial N_3}{\partial X_i}
\end{bmatrix}dS\{V_x\}\\[6pt]
&-\delta_{xi}\int_S
\begin{bmatrix}
\frac{\partial N_1}{\partial X}N_1&\frac{\partial N_1}{\partial X}N_2&\frac{\partial N_1}{\partial X}N_3\\
\frac{\partial N_2}{\partial X}N_1&\frac{\partial N_2}{\partial X}N_2&\frac{\partial N_2}{\partial X}N_3\\
\frac{\partial N_3}{\partial X}N_1&\frac{\partial N_3}{\partial X}N_2&\frac{\partial N_3}{\partial X}N_3
\end{bmatrix}dS\{P\}
\end{aligned}
\]
粘性項のy成分/圧力項のy成分
\[
\begin{aligned}
&+\frac1{Re}\int_S
\begin{bmatrix}
\frac{\partial N_1}{\partial Y}\frac{\partial N_1}{\partial Y}&\frac{\partial N_1}{\partial Y}\frac{\partial N_2}{\partial Y}&\frac{\partial N_1}{\partial Y}\frac{\partial N_3}{\partial Y}\\
\frac{\partial N_2}{\partial Y}\frac{\partial N_1}{\partial Y}&\frac{\partial N_2}{\partial Y}\frac{\partial N_2}{\partial Y}&\frac{\partial N_2}{\partial Y}\frac{\partial N_3}{\partial Y}\\
\frac{\partial N_3}{\partial Y}\frac{\partial N_1}{\partial Y}&\frac{\partial N_3}{\partial Y}\frac{\partial N_2}{\partial Y}&\frac{\partial N_3}{\partial Y}\frac{\partial N_3}{\partial Y}
\end{bmatrix}dS\{V_i\}\\[6pt]
&+\frac1{Re}\int_S
\begin{bmatrix}
\frac{\partial N_1}{\partial Y}\frac{\partial N_1}{\partial X_i}&\frac{\partial N_1}{\partial Y}\frac{\partial N_2}{\partial X_i}&\frac{\partial N_1}{\partial Y}\frac{\partial N_3}{\partial X_i}\\
\frac{\partial N_2}{\partial Y}\frac{\partial N_1}{\partial X_i}&\frac{\partial N_2}{\partial Y}\frac{\partial N_2}{\partial X_i}&\frac{\partial N_2}{\partial Y}\frac{\partial N_3}{\partial X_i}\\
\frac{\partial N_3}{\partial Y}\frac{\partial N_1}{\partial X_i}&\frac{\partial N_3}{\partial Y}\frac{\partial N_2}{\partial X_i}&\frac{\partial N_3}{\partial Y}\frac{\partial N_3}{\partial X_i}
\end{bmatrix}dS\{V_y\}\\[6pt]
&-\int_S
\begin{bmatrix}
\frac{\partial N_1}{\partial Y}N_1&\frac{\partial N_1}{\partial Y}N_2&\frac{\partial N_1}{\partial Y}N_3\\
\frac{\partial N_2}{\partial Y}N_1&\frac{\partial N_2}{\partial Y}N_2&\frac{\partial N_2}{\partial Y}N_3\\
\frac{\partial N_3}{\partial Y}N_1&\frac{\partial N_3}{\partial Y}N_2&\frac{\partial N_3}{\partial Y}N_3
\end{bmatrix}dS\{P\}
\end{aligned}
\]
表面張力項
\[
+\frac{2K^*}{We}n_i\int_L
\begin{bmatrix}N_1\\N_2\end{bmatrix}dL
\]
重力項
\[
-g_i^*\int_S
\begin{bmatrix}N_1\\N_2\\N_3\end{bmatrix}dS,
\qquad (i=1,2)
\]
内挿関数を形状関数に直す
\[
=\int_S
\begin{bmatrix}
L_1L_1&L_1L_2&L_1L_3\\
L_2L_1&L_2L_2&L_2L_3\\
L_3L_1&L_3L_2&L_3L_3
\end{bmatrix}dS\,
\frac{\{V_i\}^{\tau+\Delta\tau}-\{V_i\}^{\tau}}{\Delta\tau}
\]
対流項
\[
\begin{aligned}
&+V_x\int_S\frac1{2A}
\begin{bmatrix}
L_1c_{1x}&L_1c_{2x}&L_1c_{3x}\\
L_2c_{1x}&L_2c_{2x}&L_2c_{3x}\\
L_3c_{1x}&L_3c_{2x}&L_3c_{3x}
\end{bmatrix}dS\{V_i\}\\[6pt]
&+V_y\int_S\frac1{2A}
\begin{bmatrix}
L_1c_{1y}&L_1c_{2y}&L_1c_{3y}\\
L_2c_{1y}&L_2c_{2y}&L_2c_{3y}\\
L_3c_{1y}&L_3c_{2y}&L_3c_{3y}
\end{bmatrix}dS\{V_i\}
\end{aligned}
\]
x軸方向の粘性項と圧力項
\[
\begin{aligned}
&+\frac1{Re}\int_S\frac1{4A^2}
\begin{bmatrix}
c_{1x}c_{1x}&c_{1x}c_{2x}&c_{1x}c_{3x}\\
c_{2x}c_{1x}&c_{2x}c_{2x}&c_{2x}c_{3x}\\
c_{3x}c_{1x}&c_{3x}c_{2x}&c_{3x}c_{3x}
\end{bmatrix}dS\{V_i\}\\[6pt]
&+\frac1{Re}\int_S\frac1{4A^2}
\begin{bmatrix}
c_{1x}c_{1i}&c_{1x}c_{2i}&c_{1x}c_{3i}\\
c_{2x}c_{1i}&c_{2x}c_{2i}&c_{2x}c_{3i}\\
c_{3x}c_{1i}&c_{3x}c_{2i}&c_{3x}c_{3i}
\end{bmatrix}dS\{V_x\}\\[6pt]
&-\delta_{xi}\int_S\frac1{2A}
\begin{bmatrix}
c_{1x}L_1&c_{1x}L_2&c_{1x}L_3\\
c_{2x}L_1&c_{2x}L_2&c_{2x}L_3\\
c_{3x}L_1&c_{3x}L_2&c_{3x}L_3
\end{bmatrix}dS\{P\}
\end{aligned}
\]
y軸方向の粘性項と圧力項
\[
\begin{aligned}
&+\frac1{Re}\int_S\frac1{4A^2}
\begin{bmatrix}
c_{1y}c_{1y}&c_{1y}c_{2y}&c_{1y}c_{3y}\\
c_{2y}c_{1y}&c_{2y}c_{2y}&c_{2y}c_{3y}\\
c_{3y}c_{1y}&c_{3y}c_{2y}&c_{3y}c_{3y}
\end{bmatrix}dS\{V_i\}\\[6pt]
&+\frac1{Re}\int_S\frac1{4A^2}
\begin{bmatrix}
c_{1y}c_{1i}&c_{1y}c_{2i}&c_{1y}c_{3i}\\
c_{2y}c_{1i}&c_{2y}c_{2i}&c_{2y}c_{3i}\\
c_{3y}c_{1i}&c_{3y}c_{2i}&c_{3y}c_{3i}
\end{bmatrix}dS\{V_y\}\\[6pt]
&-\delta_{yi}\int_S\frac1{2A}
\begin{bmatrix}
c_{1y}L_1&c_{1y}L_2&c_{1y}L_3\\
c_{2y}L_1&c_{2y}L_2&c_{2y}L_3\\
c_{3y}L_1&c_{3y}L_2&c_{3y}L_3
\end{bmatrix}dS\{P\}
\end{aligned}
\]
表面張力項
\[
+\frac{2K^*}{We}n_i\int_L
\begin{bmatrix}L_1\\L_2\end{bmatrix}dL
\]
重力項
\[
-g_i^*\int_S
\begin{bmatrix}L_1\\L_2\\L_3\end{bmatrix}^{T}dS,
\qquad (i=1,2)
\]
ここで、面積積分、体積積分の公式より
\[
\int_S L_1^pL_2^qL_3^r\,dS
=\frac{p!q!r!}{(p+q+r+2)!}\,2A
\]
\[
\int_S L_iL_j\,dS=
\begin{cases}
\displaystyle \frac{1!1!}{(1+1+2)!}\,2A=\frac{2}{4!}A=\frac1{12}A,&(i\ne j),\\[6pt]
\displaystyle \frac{2!}{(1+1+2)!}\,2A=\frac{4}{4!}V=\frac1{6}A,&(i=j)
\end{cases}
\]
\[
\int_S L_i\,dS=\frac{1!}{(1+2)!}\,2A=\frac{2}{3!}A=\frac13A
\]
\[
\int_L L_1^pL_2^q\,dL=\frac{p!q!}{(p+q)!}L
\]
\[
\int_L L_i\,dL=\frac1{1!}L=L
\]
形状関数を積分すると
\[
=\frac1{12}A
\begin{bmatrix}
2&1&1\\
1&2&1\\
1&1&2
\end{bmatrix}
\frac{\{V_i\}^{\tau+\Delta\tau}-\{V_i\}^{\tau}}{\Delta\tau}
\]
対流項
\[
\begin{aligned}
&+V_x\frac1{2A}\frac{A}{3}
\begin{bmatrix}
c_{1x}&c_{2x}&c_{3x}\\
c_{1x}&c_{2x}&c_{3x}\\
c_{1x}&c_{2x}&c_{3x}
\end{bmatrix}\{V_i\}\\[6pt]
&+V_y\frac1{2A}\frac{A}{3}
\begin{bmatrix}
c_{1y}&c_{2y}&c_{3y}\\
c_{1y}&c_{2y}&c_{3y}\\
c_{1y}&c_{2y}&c_{3y}
\end{bmatrix}\{V_i\}
\end{aligned}
\]
x軸方向の粘性項と圧力項
\[
\begin{aligned}
&+\frac1{Re}\frac1{4A^2}A
\begin{bmatrix}
c_{1x}c_{1x}&c_{1x}c_{2x}&c_{1x}c_{3x}\\
c_{2x}c_{1x}&c_{2x}c_{2x}&c_{2x}c_{3x}\\
c_{3x}c_{1x}&c_{3x}c_{2x}&c_{3x}c_{3x}
\end{bmatrix}\{V_i\}\\[6pt]
&+\frac1{Re}\frac1{4A^2}A
\begin{bmatrix}
c_{1x}c_{1i}&c_{1x}c_{2i}&c_{1x}c_{3i}\\
c_{2x}c_{1i}&c_{2x}c_{2i}&c_{2x}c_{3i}\\
c_{3x}c_{1i}&c_{3x}c_{2i}&c_{3x}c_{3i}
\end{bmatrix}\{V_x\}\\[6pt]
&-\delta_{xi}\frac1{2A}\frac{A}{3}
\begin{bmatrix}
c_{1x}&c_{1x}&c_{1x}\\
c_{2x}&c_{2x}&c_{2x}\\
c_{3x}&c_{3x}&c_{3x}
\end{bmatrix}\{P\}
\end{aligned}
\]
y軸方向の粘性項と圧力項
\[
\begin{aligned}
&+\frac1{Re}\frac1{4A^2}A
\begin{bmatrix}
c_{1y}c_{1y}&c_{1y}c_{2y}&c_{1y}c_{3y}\\
c_{2y}c_{1y}&c_{2y}c_{2y}&c_{2y}c_{3y}\\
c_{3y}c_{1y}&c_{3y}c_{2y}&c_{3y}c_{3y}
\end{bmatrix}\{V_i\}\\[6pt]
&+\frac1{Re}\frac1{4A^2}A
\begin{bmatrix}
c_{1y}c_{1i}&c_{1y}c_{2i}&c_{1y}c_{3i}\\
c_{2y}c_{1i}&c_{2y}c_{2i}&c_{2y}c_{3i}\\
c_{3y}c_{1i}&c_{3y}c_{2i}&c_{3y}c_{3i}
\end{bmatrix}\{V_y\}\\[6pt]
&-\delta_{yi}\frac1{2A}\frac{A}{3}
\begin{bmatrix}
c_{1y}&c_{1y}&c_{1y}\\
c_{2y}&c_{2y}&c_{2y}\\
c_{3y}&c_{3y}&c_{3y}
\end{bmatrix}\{P\}
\end{aligned}
\]
表面張力項
\[
+\frac{2K^*}{We}n_iL
\begin{bmatrix}1\\1\end{bmatrix}
\]
境界辺上の2節点ベクトルは、要素方程式へ加算するときに境界辺の節点番号から三角形要素の3節点へ写像します。以降では
\(\mathbf b_L=A_L^T[1\;1]^T\)
と表し、例えば境界辺が要素節点1-2なら \(\mathbf b_L=[1\;1\;0]^T\) となります。
重力項
\[
-g_i^*\frac{A}{3}
\begin{bmatrix}1\\1\\1\end{bmatrix},
\qquad (i=1,2)
\]
係数をまとめて
\[
=\frac1{12}A
\begin{bmatrix}
2&1&1\\
1&2&1\\
1&1&2
\end{bmatrix}
\frac{\{V_i\}^{\tau+\Delta\tau}-\{V_i\}^{\tau}}{\Delta\tau}
\]
対流項
\[
\begin{aligned}
&+V_x\frac16
\begin{bmatrix}
c_{1x}&c_{2x}&c_{3x}\\
c_{1x}&c_{2x}&c_{3x}\\
c_{1x}&c_{2x}&c_{3x}
\end{bmatrix}\{V_i\}\\[6pt]
&+V_y\frac16
\begin{bmatrix}
c_{1y}&c_{2y}&c_{3y}\\
c_{1y}&c_{2y}&c_{3y}\\
c_{1y}&c_{2y}&c_{3y}
\end{bmatrix}\{V_i\}
\end{aligned}
\]
x軸方向の粘性項と圧力項
\[
\begin{aligned}
&+\frac1{Re}\frac1{4A}
\begin{bmatrix}
c_{1x}c_{1x}&c_{1x}c_{2x}&c_{1x}c_{3x}\\
c_{2x}c_{1x}&c_{2x}c_{2x}&c_{2x}c_{3x}\\
c_{3x}c_{1x}&c_{3x}c_{2x}&c_{3x}c_{3x}
\end{bmatrix}\{V_i\}\\[6pt]
&+\frac1{Re}\frac1{4A}
\begin{bmatrix}
c_{1x}c_{1i}&c_{1x}c_{2i}&c_{1x}c_{3i}\\
c_{2x}c_{1i}&c_{2x}c_{2i}&c_{2x}c_{3i}\\
c_{3x}c_{1i}&c_{3x}c_{2i}&c_{3x}c_{3i}
\end{bmatrix}\{V_x\}\\[6pt]
&-\delta_{xi}\frac16
\begin{bmatrix}
c_{1x}&c_{1x}&c_{1x}\\
c_{2x}&c_{2x}&c_{2x}\\
c_{3x}&c_{3x}&c_{3x}
\end{bmatrix}\{P\}
\end{aligned}
\]
y軸方向の粘性項と圧力項
\[
\begin{aligned}
&+\frac1{Re}\frac1{4A}
\begin{bmatrix}
c_{1y}c_{1y}&c_{1y}c_{2y}&c_{1y}c_{3y}\\
c_{2y}c_{1y}&c_{2y}c_{2y}&c_{2y}c_{3y}\\
c_{3y}c_{1y}&c_{3y}c_{2y}&c_{3y}c_{3y}
\end{bmatrix}\{V_i\}\\[6pt]
&+\frac1{Re}\frac1{4A}
\begin{bmatrix}
c_{1y}c_{1i}&c_{1y}c_{2i}&c_{1y}c_{3i}\\
c_{2y}c_{1i}&c_{2y}c_{2i}&c_{2y}c_{3i}\\
c_{3y}c_{1i}&c_{3y}c_{2i}&c_{3y}c_{3i}
\end{bmatrix}\{V_y\}\\[6pt]
&-\delta_{yi}\frac16
\begin{bmatrix}
c_{1y}&c_{1y}&c_{1y}\\
c_{2y}&c_{2y}&c_{2y}\\
c_{3y}&c_{3y}&c_{3y}
\end{bmatrix}\{P\}
\end{aligned}
\]
表面張力項
\[
+\frac{2K^*}{We}n_iL
\begin{bmatrix}1\\1\end{bmatrix}
\]
重力項
\[
-g_i^*\frac{A}{3}
\begin{bmatrix}1\\1\\1\end{bmatrix},
\qquad (i=1,2)
\]
行列式をまとめると
\[
\begin{aligned}
&={}[C]\frac{\{V_i\}^{\tau+\Delta\tau}-\{V_i\}^{\tau}}{\Delta\tau}
+V_x[C_x]\{V_i\}+V_y[C_y]\{V_i\}\\[6pt]
&+\frac1{Re}[S_{xx}]\{V_i\}+\frac1{Re}[S_{xi}]\{V_x\}-\delta_{xi}[H_x]\{P\}\\[6pt]
&+\frac1{Re}[S_{yy}]\{V_i\}+\frac1{Re}[S_{yi}]\{V_y\}-\delta_{yi}[H_y]\{P\}\\[6pt]
&+\frac{2K^*}{We}Ln_i\begin{bmatrix}1\\1\end{bmatrix}
-g_i^*\frac{A}{3}\begin{bmatrix}1\\1\\1\end{bmatrix},
\qquad (i=1,2)
\end{aligned}
\]
行列ごとにまとめると
\[
\begin{aligned}
&={}[C]\frac{\{V_i\}^{\tau+\Delta\tau}-\{V_i\}^{\tau}}{\Delta\tau}
+(V_x[C_x]+V_y[C_y])\{V_i\}\\[6pt]
&+\frac1{Re}([S_{xx}]+[S_{yy}])\{V_i\}\\[6pt]
&+\frac1{Re}([S_{xi}]\{V_x\}+[S_{yi}]\{V_y\})\\[6pt]
&-(\delta_{xi}[H_x]+\delta_{yi}[H_y])\{P\}\\[6pt]
&+\frac{2K^*}{We}Ln_i\begin{bmatrix}1\\1\end{bmatrix}\\[6pt]
&-g_i^*\frac{A}{3}\begin{bmatrix}1\\1\\1\end{bmatrix},
\qquad (i=1,2,3)\\[6pt]
&={}\begin{bmatrix}0\\0\\0\end{bmatrix}
\end{aligned}
\]
最終的に次式が導出されます。
\[
\begin{aligned}
[C]\frac{\{V_i\}^{\tau+\Delta\tau}-\{V_i\}^{\tau}}{\Delta\tau}
&+(V_x[C_x]+V_y[C_y])\{V_i\}\\[6pt]
&+\frac1{Re}([S_{xx}]+[S_{yy}])\{V_i\}\\[6pt]
&+\frac1{Re}([S_{xi}]\{V_x\}+[S_{yi}]\{V_y\})\\[6pt]
&-(\delta_{xi}[H_x]+\delta_{yi}[H_y])\{P\}\\[6pt]
&+\frac{2K^*}{We}Ln_i\begin{bmatrix}1\\1\end{bmatrix}
-g_i^*\frac{A}{3}\begin{bmatrix}1\\1\\1\end{bmatrix}
=\begin{bmatrix}0\\0\\0\end{bmatrix},
\qquad (i=1,2)
\end{aligned}
\]
既知の項を右辺に移項します。
\[
\begin{aligned}
\frac{[C]}{\Delta\tau}\{V_i\}^{\tau+\Delta\tau}
&+(V_x[C_x]+V_y[C_y])\{V_i\}^{\tau+\Delta\tau}\\[6pt]
&+\frac1{Re}([S_{xx}]+[S_{yy}])\{V_i\}^{\tau+\Delta\tau}\\[6pt]
&+\frac1{Re}([S_{xi}]\{V_x\}^{\tau+\Delta\tau}+[S_{yi}]\{V_y\}^{\tau+\Delta\tau})\\[6pt]
&-(\delta_{xi}[H_x]+\delta_{yi}[H_y])\{P\}^{\tau+\Delta\tau}\\[6pt]
&={}\frac{[C]}{\Delta\tau}\{V_i\}^{\tau}
-\frac{2K^*}{We}Ln_i\begin{bmatrix}1\\1\end{bmatrix}
+g_i^*\frac{A}{3}\begin{bmatrix}1\\1\\1\end{bmatrix},
\qquad (i=1,2)
\end{aligned}
\]
x軸方向の成分は次式となります。
\[
\begin{aligned}
\frac{[C]}{\Delta\tau}\{V_x\}^{\tau+\Delta\tau}
&+(V_x[C_x]+V_y[C_y])\{V_x\}^{\tau+\Delta\tau}\\[6pt]
&+\frac1{Re}\left\{(2[S_{xx}]+[S_{yy}])\{V_x\}^{\tau+\Delta\tau}+[S_{yx}]\{V_y\}^{\tau+\Delta\tau}-[H_x]\{P\}^{\tau+\Delta\tau}\right\}\\[6pt]
&={}\frac{[C]}{\Delta\tau}\{V_x\}^{\tau}
-\frac{2K^*}{We}Ln_x\begin{bmatrix}1\\1\end{bmatrix}
+g_x^*\frac{A}{3}\begin{bmatrix}1\\1\\1\end{bmatrix}
\end{aligned}
\]
y軸方向の成分は次式となります。
\[
\begin{aligned}
\frac{[C]}{\Delta\tau}\{V_y\}^{\tau+\Delta\tau}
&+(V_x[C_x]+V_y[C_y])\{V_y\}^{\tau+\Delta\tau}\\[6pt]
&+\frac1{Re}\left\{[S_{xy}]\{V_x\}^{\tau+\Delta\tau}+([S_{xx}]+2[S_{yy}])\{V_y\}^{\tau+\Delta\tau}-[H_y]\{P\}^{\tau+\Delta\tau}\right\}\\[6pt]
&={}\frac{[C]}{\Delta\tau}\{V_y\}^{\tau}
-\frac{2K^*}{We}Ln_y\begin{bmatrix}1\\1\end{bmatrix}
+g_y^*\frac{A}{3}\begin{bmatrix}1\\1\\1\end{bmatrix}
\end{aligned}
\]
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