I came across the following article on black hole simulations in water tanks and it made me wonder if these simulations have been used to model primordial black holes during an early universe effectively 'bounded' by the limits of space time?

https://phys.org/news/2021-02-backre...imulation.html
The researchers used a water tank simulator consisting of a draining vortex, like the one that forms when you pull the plug in the bath. This mimics a black hole since a wave which comes too close to the drain gets dragged down the plug hole, unable to escape. Systems like these have grown increasingly popular over the past decade as a means to test gravitational phenomena in a controlled laboratory environment. In particular, Hawking radiation has been observed in an analog black hole experiment involving quantum optics.

Using this technique the researchers showed for the first time that when waves are sent into an analog black hole, the properties of the black hole itself can change significantly. The mechanism underlying this effect in their particular experiment has a remarkably simple explanation. When waves come close to the drain, they effectively push more water down the plug hole causing the total amount of water contained in the tank to decrease. This results in a change in the water height, which in the simulation corresponds to a change in the properties of the black hole.
When you create a vortex in a circular coffee cup it will gradually fade away after you stop stirring but if you use a hexagonal cup you will notice an interesting phenomena, that as the bounded vortex decays it will reach a point where it turns into an attenuating wave that moves from the center of the cup to the sides and back again several times before fading away. You can try this at home if you like and see for yourself.