Cleansing action in residential toilets is all in the swirl, both in velocity and duration. I have never attempted to mearsure the velocity generated in my Gerber, but it IS impressive and lasts 8 seconds.

Regarding depth of the the water, such a discussion may actually be a little too delicate for some, but us engineers have been tasked with getting things right so we have to take everything into account when designing any system. Thereto, briefly,

Where,