Wiktionary
antivortex
n. (context physics English) A vortex that rotates in an opposite direction to another that it is paired with
Usage examples of "antivortex".
And there were antivortex baffles, like huge propeller blades, to prevent the buildup of whirlpools—like those above the plug hole of a draining bath—that could suck bubbles of vapor into the feed pipes.