boil, ferment, seethe, uproar, breed
湧 centers on something welling up from within: liquid boiling or seething, a fermenting process, or a sudden uproar. The idea of breeding can be seen as a vigorous, generative surge.
湧 combines 氵 (water) with 勇, which likely contributes both sound and the idea of vigorous movement, suggesting water welling up or boiling.
Water 氵 plus 勇 (bravery) suggests water bravely bubbling up: boiling, fermenting, or causing an uproar as it surges forth.
For ユウ, imagine you watching a pot of water suddenly boil over: you -> ユウ, and the water wells up vigorously.
to well (up); to gush out (of water); to spring out; to surge
spring water
to gush forth (e.g. water from a spring); to flow (out); to stream (out); to bubble up
gushing out; welling up; springing up
to boil up; to come to the boil; to seethe
(appearing) out of nowhere; as if one had fallen from the sky or sprung from the ground
those who seek riches will find them; fortune comes to those who seek it
to feel that something is true or actually happening; to hit one (realization, thought); to sink in
to breed (e.g. maggots); to let breed
welling (up); gushing forth (of water); springing out; surging
to gush out
to appear suddenly
output
upwelling
welling of water; spring water; spring
bubbling spring; gushing spring; fountain
hydrothermal discharge zone
to tingle with excitement; to be full of excitement; to be thrilled
to happen suddenly; to occur unexpectedly; to appear out of the blue