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Simulation Nozzle and Spray

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Hello at all
I am new at Comsol and have not any experince at Comsol. I try to simulate a nozzle from a spraying system and i will know the fly-curve and fly-time at a special room, but i have no idea how i can solve this problem. The nozzle is a hollow cone. The medium is water with i want spray at a vaccum of 40mbar. Can anybody give me some tipps how i can solve this problem?

Thanks

6 Replies Last Post Jan 16, 2017, 12:27 p.m. EST
Jim Freels mechanical side of nuclear engineering, multiphysics analysis, COMSOL specialist

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Posted: 1 decade ago Mar 2, 2010, 9:46 a.m. EST
Start by drawing the geometry with COMSOL.
Start by drawing the geometry with COMSOL.

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Posted: 1 decade ago Mar 2, 2010, 10:24 a.m. EST
I done this. but then i have no idea which physics behind the spraying process and i have not find any literatur about such processes. i think perhaps navier stokes. The nozzle-typ is a hollow cone. So i have a thin layer at first, which break at small droplets. But i dont know how i can descrbe this process with equations.
I done this. but then i have no idea which physics behind the spraying process and i have not find any literatur about such processes. i think perhaps navier stokes. The nozzle-typ is a hollow cone. So i have a thin layer at first, which break at small droplets. But i dont know how i can descrbe this process with equations.

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Posted: 1 decade ago Mar 2, 2010, 1:29 p.m. EST
Michael,

I hesitated before I decided to respond because I don't like discouraging people but I think what you are wanting to do is a hugely monumental task and you don't realize what you are up against :) Please forgive my candor.

Simulating drop breakup/spray formation from first principles is very hard because 1- the underlying physics is non-trivial (not that N-S is trivial itself, but this is even more complicated due to the nature of free surface BCs) and 2- implemeting this computationally is very difficult too. Belive me I would know because I spent my entire Ph.D. coming up with a way of doing this for a single droplet and simulating it with finite element code that I wrote myself.

I suggest you find some literature and read up on the subject to see for yourself the underlying physics/math before you even begin to worry about simulating it.

If you need engineering answers there might be other feasible ways of getting them (engineering correlations, experiments etc.). Although I am a computational guy myself, CFD is not always the best way to go after a problem- it all depends on what you want and what your constraints are.

Hope this helps
Ozgur

Michael, I hesitated before I decided to respond because I don't like discouraging people but I think what you are wanting to do is a hugely monumental task and you don't realize what you are up against :) Please forgive my candor. Simulating drop breakup/spray formation from first principles is very hard because 1- the underlying physics is non-trivial (not that N-S is trivial itself, but this is even more complicated due to the nature of free surface BCs) and 2- implemeting this computationally is very difficult too. Belive me I would know because I spent my entire Ph.D. coming up with a way of doing this for a single droplet and simulating it with finite element code that I wrote myself. I suggest you find some literature and read up on the subject to see for yourself the underlying physics/math before you even begin to worry about simulating it. If you need engineering answers there might be other feasible ways of getting them (engineering correlations, experiments etc.). Although I am a computational guy myself, CFD is not always the best way to go after a problem- it all depends on what you want and what your constraints are. Hope this helps Ozgur

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Posted: 1 decade ago Aug 23, 2010, 1:51 p.m. EDT
I am also interested in spray simulation for liquids, nozzles.

So is it save to assume that Comsol is not the program I'm looking for?
Here they mention nozzles: www.comsol.com/products/cfd/?tab=appareas but I guess that is an optimistic marketing thing.

Did anyone see a simulation model with mist?
I am also interested in spray simulation for liquids, nozzles. So is it save to assume that Comsol is not the program I'm looking for? Here they mention nozzles: http://www.comsol.com/products/cfd/?tab=appareas but I guess that is an optimistic marketing thing. Did anyone see a simulation model with mist?

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Posted: 7 years ago Nov 25, 2016, 1:25 a.m. EST
i came through your post because i have same model that i have to use for my thesis, so is there any luck to simulate nozzle spray (mist)?





Thanks
i came through your post because i have same model that i have to use for my thesis, so is there any luck to simulate nozzle spray (mist)? Thanks

Stephen Haralampu Certified Consultant

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Posted: 7 years ago Jan 16, 2017, 12:27 p.m. EST
I agree about the complexity of this problem. Droplet breakup in a nozzle is largely governed by flow non-idealities at the surface of the ligand. Numerically, these instabilities are difficult to quantify. Then tracking the free surface formation from fundamental principles becomes a monumental task. There are many empirical models for drop formation, but are limited to specific nozzle designs. You might be able to couple a finite element approach for flow within a nozzle with the empirical equations for the breakup to get what you need.
I agree about the complexity of this problem. Droplet breakup in a nozzle is largely governed by flow non-idealities at the surface of the ligand. Numerically, these instabilities are difficult to quantify. Then tracking the free surface formation from fundamental principles becomes a monumental task. There are many empirical models for drop formation, but are limited to specific nozzle designs. You might be able to couple a finite element approach for flow within a nozzle with the empirical equations for the breakup to get what you need.

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