Predicting when a liquid flow will break into droplets

[Jeff Corkern]

The following is also posted in the Chemistry forum. This is a cross-post. If this is not allowed, it's fine with me if this post is deleted by an admin.

I would like to know how to predict when a flow of liquid---dichloromethane, actually---freely flowing downward through a small hole (varying from around .05 to .001 cm) will exit as droplets instead of flowing in a steady stream. I have been bouncing around the Internet for a good while now and everything I find is either too specialized or grade-school level. I'm not interested in the flow of polymer solutions, just a plain old low-viscosity Newtonian fluid.

I've learned how to predict flow rate using Poiseuille's Law and drop size using Tate's Law. Now I need to know how to predict if the flow will be a steady stream or drops. Drops is what I want, actually.

I need something simple, not something complicated.

My own chemistry/mathematical/physical background:Simple quantum mechanics. Mathematics through simple differential equations. Vector calculus. E&M theory, i.e. applications and analysis of Maxwell's Equations. Thermodynamics and statistical thermodynamics.

So I can handle a certain amount of math.

Anybody here have any links? TIA.

Jeff Corkern
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"If people possesses immortal souls, it should be possible to deduce this by logical analysis of their behavior."

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[PerennialII]

Have you tried looking for two-phase or multi-phase flow (and perhaps thermohydraulic analyses)? I'm thinking that might be what you're after. Don't know of any decent online sources though, would probably hit www.cfd-online.com and start browsing ("elementary" books, manuals of various software packages would be my first pick for material).

 

[Jeff Corkern]

Have you tried looking for two-phase or multi-phase flow (and perhaps thermohydraulic analyses)? I'm thinking that might be what you're after. Don't know of any decent online sources though, would probably hit www.cfd-online.com and start browsing ("elementary" books, manuals of various software packages would be my first pick for material).

Thanks for the URL. I'll check them out.

The question I ask has already been completely solved numerically, would you believe, the solution's just not available to me. The ink-jet industry had a HUGE financial interest in solving that particular problem. Some massive model with like 50,000 parameters, according to the newspaper article I read.

Jeff Corkern
--------------------------------------------------------------------------------------
Consider the following as a statement of logic and rank it as "True" or "False."

"If people possesses immortal souls, it should be possible to deduce this by logical analysis of their behavior."

www.theninepointfivetheses.blogspot.com
--------------------------------------------------------------------------------------

 

[PerennialII]

yeah I'd say numerically it's "fairly solvable" (not your simplest CFD model but still not the hardest can imagine), and several (even) commercial packages have models to predict two phase flow for one. Probably most common application is steam, bubbles and all that, but can use to model for example rain and this sounds like a similar problem.