Keeping two immiscible liquids well-mixed in a tube due to high Re alone

[plantprowler]

If you co-feed two immiscible liquids (low viscosity; no tendency to emulsify) into a long, small diameter tube, say 10 mm dia and maybe 20 m length could you keep them well mixed by turbulence alone?

i.e. Say the Reynolds No. (Re) was maintained high by pumping at a high velocity, e.g. 20,000 would you expect a good interfluid mixing. i.e. If I sampled various parts of the tubes cross section would I get pretty even mix of Fluid A and Fluid B? We can assume the densities are different e.g. 0.8 and 1.1 gm/cc maybe.

My prior knowledge on this subject makes me think "No", and this is why we use static mixers etc. but I am reading something that made me question my intuitions on this.

My impression was that unless you have internals (e.g. static mixers) to remix them or add some sort of stable dispersion agent the natural tendency for the fluids to segregate based on density is always going to win over the initial turbulence you introduced into the system beyond some length. Maybe 100 pipe diameters max.

Any comments? Is it possible to keep two imiscible liquids mixed using a high Re alone?

 

[moltenmetal]

You might be able to achieve this in a larger diameter tube in turbulent flow, but a small diameter tube is a) hard to achieve a high Re in due to pressure drop and b) represents a lot of surface area which will tend to coalesce one or the other phase.

Static mixers have a better shot at keeping the phases mixed.