Buoyant thermal mass balance
= Buoyant thermal mass balance
If a <buoyant thermal> receives volume inflow $J$ with <reduced gravity> $g_p$ and receives no other <fluid entrainment>, its mass and volume balances imply $\dot V=J$ and $d(g_tV)/dt=g_pJ$. If $V\propto t^{9/4}$ and $g_t\propto t^{-5/4}$, then $g_t=9g_p/4$.