Is there a name for this anime/manga visual convention? sometimes when a character is frustrated or has failed to do something, a cloud made of moving squiggly lines will form above their head (it's somewhat of a common trope in video games that use speech bubbles too.)  



Is there a name for this anime/manga visual convention?
Yes, this pictorial rune has the name: twirl.

These pictorial rune's originate from Forceville's categorization, which mostly describes the location/orientation.

  

This is often used to depict movement as well as confusion, as described by samcyb


 Forcevile Image source: source