The Equation of Continuity

流体连续性方程

$\color{Blue} {The\quad Equation \quad of \quad Continuity} $

流体连续性方程表达通式

物理意义: 物质进入系统的量等于 物质离开离开系统的量与物质在系统内累积量的加和。


1.直角坐标系($ x, y, z $)

直角坐标系Cartesian coordinates ($\textit { x,y,z }$): NO.
$\dfrac {\partial \rho}{\partial t}+\dfrac {\partial}{\partial x}(\rho v_x)+\dfrac {\partial}{\partial y}(\rho v_y) +\dfrac {\partial}{\partial z}(\rho v_z)=0$ 1-1

2.圆柱坐标系($r,\theta, z$)

圆柱坐标系Cylindrical coordinates coordinates ($\textit {r, $\theta$, z }$): NO.
$\dfrac {\partial \rho}{\partial t}+\dfrac {1}{r}\dfrac {\partial}{\partial r}(\rho r v_r)+\dfrac {1}{r} \dfrac {\partial}{\partial \theta}(\rho v_\theta) +\dfrac {\partial}{\partial z}(\rho v_z)=0$ 2-1

3.球坐标系($r, \theta, \phi $)

球坐标系Spherical coordinates($\textit {r, $\theta$, $\phi$ }$): NO.
$\dfrac {\partial \rho}{\partial t}+\dfrac {1}{r^2}\dfrac {\partial}{\partial r}(\rho r^2 v_r)+\dfrac {1}{r sin\theta} \dfrac {\partial}{\partial \theta}(\rho v_\theta sin\theta) +\dfrac {1}{r sin\theta}\dfrac {\partial}{\partial \phi}(\rho v_\phi)=0$ 3-1


参考文献

  1. R. Byron Bird, Warren E. stewart, Edwin N. Lightfoot. Transport phenomena:Revised second edition John Wiely &Sons, Inc.
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