Ideal magnetohydrodynamic induction equation (source code)

= Ideal magnetohydrodynamic induction equation
{title2=ideal MHD induction equation}

The ideal magnetohydrodynamic induction equation is $\partial_t\mathbf B=\nabla\times(\mathbf u\times\mathbf B)$. Together with $\nabla\mathbin\cdot\mathbf B=0$, it implies magnetic-flux freezing.