As a whirlpool of boiling waters has a centre point, so, all this raging circled round Defarge’s wine-shop, and every human drop in the caldron had a tendency to be sucked towards the vortex where Defarge himself, already begrimed with gunpowder and sweat, issued orders, issued arms, thrust this man back, dragged this man forward, disarmed one to arm another, laboured and strove in the thickest of the uproar.
There are no more uses of "vortex" in the book.
Show samples from other sources
The tunnel ended in a whirling vortex of darkness.
Cassandra Clare -- City of Heavenly Fire
What happens is the water spray creates a vortex, kind of like a hurricane.