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# Can the pressure of an input water source in a laminar flow setup be variable?

i.e. Can I change the total ballistic traveling distance of the water stream by lowering/raising the water pressure into the laminar flow nozzle assembly?

I can't seem to find any theory/equations regarding laminar water flow and how pressure fits into its creation.

Thanks for any help everyone!

## Discussions

Best Answer 8 years ago

Since the Reynolds number of the stream is dependent on diameter, viscosity and velocity, providing the increase in pressure doesn;t cause the critical Reynolds number to be exceeded you should be OK.

Steve

Answer 8 years ago

+1. there's a range of pressures that can be used for a given fluid and pipe geometry. Basically, you want to avoid sheer at the boundary layer. At least the way I interpret the mechanics. Micro vortices begin to form as the sheer stresses at the transition from fluid to solid (the boundary layer) start to exceed the adhesion of the fluid to wall, and after a quick stint in transitional flow, suddenly voila turbulent flow! I'm no expert, so that's essentially a lay interpretation based on working in a flow lab for ~5 years, but over twenty ago. it *seems right to me, at least conceptually, but idk if it's smack-on accurate

Look at the library for books on Fluid Dynamics or "Fluid and Thermal Physics" (or even call or stop by a local university's mech E department....they may have old textbooks available for sale, or if you get lucky, you may end up talking to a prof like my dad, who used to evaluate textbooks and had literally stacks of good but essentially "garbage" textbooks on his office floor...math though..yawn) When he retired, he had hundreds of them...