User:Verdy p/sandbox

$$u\frac{\partial u}{\partial x}+v\frac{\partial u}{\partial y}+w\frac{\partial u}{\partial z}+\lambda_1\begin{pmatrix} u^2\frac{\partial^2 u}{\partial x^2}+v\frac{\partial^2 u}{\partial y^2}+w^2\frac{\partial^2 u}{\partial z^2}\\+2uv\frac{\partial^2 u}{\partial x\partial y}+2vw\frac{\partial^2 u}{\partial y\partial z}+2uw\frac{\partial^2 u}{\partial x\partial z} \end{pmatrix} = \nu\frac{\partial^2 u}{\partial z^2}$$