Constant viscosity in radiation-supported vertical balance (source code)

= Constant viscosity in radiation-supported vertical balance
{title2=$\mu=4c/(9\kappa)$}

Combining $F=c\Omega^2z/\kappa$ with viscous heating $dF/dz=(9/4)\mu\Omega^2$ gives a height-independent <dynamic viscosity> $\mu=4c/(9\kappa)$ under constant <opacity>. This exact limiting relation differs from an approximate vertically averaged <alpha disk> closure.