Analyse vectorielle/Fiche/Formulaire d'analyse vectorielle

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Fiche-mémoire sur l'analyse vectorielle


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[modifier] Coordonnées cartésiennes

La base est (\vec u_x,\vec u_y,\vec u_z).

\vec\nabla=\frac{\partial}{\partial x}\vec u_x+\frac{\partial}{\partial y}\vec u_y+\frac{\partial}{\partial z}\vec u_z
\mathrm{div}(\vec A)=\frac{\partial A_x}{\partial x}+\frac{\partial A_y}{\partial y}+\frac{\partial A_z}{\partial z}
\Delta=
\frac{\partial^2}{\partial x^2 } +
\frac{\partial^2}{\partial y^2 } +
\frac{\partial^2}{\partial z^2 }
\overrightarrow\operatorname{rot}\ \vec F = \vec \nabla \wedge \vec F =
\left(\frac{\partial F_z}{\partial y}-\frac{\partial F_y}{\partial z}\right)\vec u_x
+\left(\frac{\partial F_x}{\partial z} - \frac{\partial F_z}{\partial x}\right)\vec u_y
+\left(\frac{\partial F_y}{\partial x} - \frac{\partial F_x}{\partial y}\right)\vec u_z

[modifier] Coordonnées cylindriques

La base est (\vec u_r,\vec u_\theta,\vec u_z).

\vec\nabla
= \frac{\partial}{\partial r}\vec u_r
+ \frac{1}{r}\frac{\partial}{\partial \theta}\vec u_\theta
+ \frac{\partial}{\partial z}\vec u_z
\mathrm{div}(\vec A)=\frac1r\frac{\partial rA_r}{\partial r}+\frac1r\frac{\partial A_\theta}{\partial\theta}+\frac{\partial A_z}{\partial z}
\Delta f
= \frac{1}{r} \frac{\partial}{\partial r} \left( r \frac{\partial f}{\partial r} \right) 
+ \frac{1}{r^2} \frac{\partial^2 f}{\partial \phi^2}
+ \frac{\partial^2 f}{\partial z^2 }
\vec\Delta\vec A
=\left[\Delta A_r-\frac1{r^2}\left(A_r+2\frac{\partial A_\theta}{\partial \theta}\right)\right]\vec u_r
+ \left[\Delta A_\theta-\frac1{r^2}\left(A_\theta-2\frac{\partial A_r}{\partial \theta}\right)\right]\vec u_\theta
+ \Delta A_z \vec u_z
\operatorname{rot}\,\vec{A}=\left(\frac{1}{r}\frac{\partial A_z}{\partial \theta}-\frac{\partial A_\theta}{\partial z}\right)\vec{u_r} + \left(\frac{\partial A_r}{\partial z}-\frac{\partial A_z}{\partial r}\right)\vec{u_\theta} + \frac{1}{r}\left(\frac{\partial}{\partial r}(rA_\theta)-\frac{\partial A_r}{\partial \theta}\right)\vec{u_z}

[modifier] Coordonnées sphériques

\vec\nabla f
= \frac{\partial f}{\partial r}\vec u_r
+ \frac{1}{r}\frac{\partial f}{\partial \theta}\vec u_\theta
+ \frac{1}{r \sin\theta}\frac{\partial f}{\partial \phi}\vec u_\phi
\Delta f 
= \frac{1}{r^2} \frac{\partial}{\partial r}\left( r^2 \frac{\partial f}{\partial r} \right) 
+ \frac{1}{r^2 \sin \theta} \frac{\partial}{\partial \theta} \left( \sin \theta \frac{\partial f}{\partial \theta} \right) 
+ \frac{1}{r^2 \sin^2 \theta} \frac{\partial^2 f}{\partial \phi^2}
\operatorname{rot}\,\vec{A}
 =   \frac{1}{r\sin\theta}\left(\frac{\partial}{\partial \theta}(\sin\theta A_\varphi)-\frac{\partial A_\theta}{\partial \varphi}\right)\vec{u_r}
   + \left(\frac{1}{r\sin\theta}\frac{\partial A_r}{\partial \varphi}-\frac{1}{r}\frac{\partial}{\partial r}(rA_\varphi)\right)\vec{u_\theta}
   + \frac{1}{r}\left(\frac{\partial}{\partial r}(rA_\theta)-\frac{\partial A_r}{\partial \theta}\right)\vec{u_\varphi}

[modifier] Composition des opérateurs

  • \mathrm{div}\left(\overrightarrow{\rm rot}(\vec A)\right)=0