#### Clausius2

Science Advisor

Gold Member

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[tex] \frac{\partial u}{\partial

x}+\frac{1}{r}\frac{\partial}{\partial r}(vr)=0

[/tex]

[tex] u\frac{\partial u}{\partial x}+v \frac{\partial

u}{\partial r}=\frac{1}{r}\frac{\partial}{\partial r}\Big(r

\frac{\partial u}{\partial r}\Big)

[/tex]

Any idea?. I have read some ways of doing so by establishing a complicated matrix of coefficients, but it is only valid for linear equations.

Thanks in Advance!