The name Rhealyn means beautiful flowing stream. I know this because it's my name. ;-)
Whitewater.
The Gulf Stream
I know of no special name for southerly flowing streams. 'Draining in a southerly direction' would perhaps be a description.
Boil Line Tailrace
Gulf Stream
The difference between a river and a stream is the name applied to it by local residents, and relative size. In the same region, something called a river is usually larger than something called a stream. However, something that is called a river in one place could be the same size as something called a stream in another place.
Confluence means coming together, joining or flowing together at a single place. An example would the joining of two streams to form a single combined stream like the Missouri and Mississippi Rivers join into a single stream (river) near St Louis MO. It can also be a name for the place where they meet or be applied to the resultant stream.
A stream.
Flowing electricity is called electric current.
flowing
The Jet stream got it's name by being as strong as jets