Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: scientizscht on 26/03/2020 10:08:14

Title: Can bulk diffusion prevent normal diffusion?
Post by: scientizscht on 26/03/2020 10:08:14

Let's say we have a pipe with a solution moving at a specific speed. If we connect a vertical tube to the pipe that contains water, will the solute from the moving liquid in the pipe diffuse to the vertical tube?

If yes, will it diffuse at the same or different rate?

Title: Re: Can bulk diffusion prevent normal diffusion?
Post by: yor_on on 28/03/2020 12:45:53
First of all it depends on where you join the vertical pipe to the horizontal. At the bottom , at the top? That's because you have to count in gravity for it even though the 'force' of it may not be particularly strong. Then it depends on if the main (horizontal) pipe is fully filled with your solution, its density pressure speed etc. Presuming it fully filled, up to the brink, and your vertical pipe joining the horizontal from the top it should create a turbulence which means that some water will get diverted into the vertical, thereby also losing kinetic energy for the main flow. As it lose kinetic energy it also should lose some speed, well, as I think then. And then there is the shape of that vertical opening too, size etc.

The Romans used a similar technique in their aqueducts to create turbulence by making small openings with a obstruction at its sides at intervalls, getting their 'pipes' to clean themselves which was pretty smart. Someone there understood fluid dynamics on either a intuitive or mathematical plane.

This may be questioned as you can have f.ex 'whirlpools' standing more or less 'still' in a river, meaning that you can think of it as 'layers upon layers' of different 'speeds' too.