Bernoulli invariant (source code)

= Bernoulli invariant
{c}
{title2=$b=u^2/2+\Phi+w$}

In a steady adiabatic inviscid fluid with a conservative body force, the <Bernoulli invariant> is the displayed specific energy, constant along each <streamline>. Dotting the <Euler equations> with velocity and using the <specific enthalpy> identity gives $\mathbf u\cdot\nabla b=0$. In <ideal magnetohydrodynamics>, magnetic work need not vanish; the <planar ideal-MHD Bernoulli invariant> includes the corresponding electromagnetic correction.