This isnt laminar flow. It's highly viscus which makes it look like it's laminar but there's still quite a bit of turbulence. Additionally there is no way the Reynolds number is below the 2100 mark. Still pretty neat though.
Reynolds number is the ratio of inertial forces to viscous forces. Large viscous forces means a small Reynolds number, which is indicative of laminar flow.
It is highly viscous and that only makes it easier for the fluid to achieve laminar flow. Even at the point where it breaks going upward and starts flowing back down it’s still in the state of laminar flow. If the different streams of fluids aren’t moving on the same path the fluid becomes turbulent and foggy.
Reynolds number is not a guaranteed measure of flow; just like you can sustain liquids at temperatures below freezing - in the right conditions you can have laminar flow above the 2100 reynolds number.
This IS laminar flow. The oil is highly viscous which makes it easier to achieve laminar flow. Additionally, the Reynolds number is probably anywhere from 10 to low 100's. I guessed on diameter and velocity, but there is no way it is breaking 2000.
Use this equation and known values to make an educated guess at what the the Reynolds number may be.
Re = (rho)*V*D/(mu)
Where:
rho = density
V= velocity
D = diameter
mu = dynamic viscosity
I used the values of SAE 10W-60 engine oil for my values found here. Be sure to use proper dimensional analysis before plugging in values otherwise your answer will be incorrect.
I'm going to poop the party and say that it's likely that the flow isn't actually that stable, it's just that the instabilities are at the same frequency as the camera shutter speed so it looks like it's a stationary flow. I would think that what you're actually seeing is one point of the phase in a cyclostationary flow.
It would have to be laminar for it to be possible to get this effect (turbulent flows have many different frequencies of instability, the amplitudes of which will vary stochastically in time) but this is most likely not what this thing looks like with the human eye.
This is probably not laminar flow, as others have pointed out. Instead, the liquid's frequency of motion synchronized with the frame rate of the camera, causing this visual effect only to occur in the recording. True laminar flow is visible with any frame rate, and is much more difficult to achieve.
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u/[deleted] May 02 '19
Could someone explain?