做个笔记



  • \begin{equation}
    \frac{\mathrm{D}K}{\mathrm{D}t} = \frac{1}{2}\frac{\mathrm{D}|\mathbf{U}|^2 }{\mathrm{D}t}
    = \frac{1}{2}\frac{\mathrm{D} u_i^2 }{\mathrm{D}t}
    = \frac{1}{2} \left( \frac{\partial u_i^2}{\partial t} + \mathbf{U} \cdot \nabla u_i^2 \right) \
    = u_i \frac{\partial u_i}{\partial t} + \mathbf{U} \cdot u_i \nabla u_i
    = \frac{\mathrm{D} \mathbf{U}}{\mathrm{D} t} \cdot \mathbf{U}
    \label{KK}
    \end{equation}

    :sunglasses:



  • $\mathrm{TV}=\sum_{i}^{}|\phi_{i+1}-\phi_{i}|$


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