Flow modeling in 2D geometry as helical coil.

Ash Kot · January 6, 2021, 20:25

Hello Sir/Ma'am,

I'm trying to setup helical coil heat exchanger using 2D geometry. Now if one takes cross-section of 3D helical coil, then the person should see bunch of circles aligned next to each other in form of array. Sure, its not possible to setup helical flow in this 2D section because all 3 dimensions play critical role. The flow moves X,Y,Z directions.

Now, correct me if I'm wrong but if I put the periodic boundary conditions for each of these circles and periodicity setup only for velocity variable, will it work?
The attached geometry shall provide 'some-what' idea that I'm talking about

Gert-Jan · January 7, 2021, 10:32

Maybe the approach as described in the PhD thesis of Jasper Kelder from The Eindhoven University of Technology might help:

https://research.tue.nl/en/publicati...al-sterilisers

evcelica · January 7, 2021, 13:16

I would not recommend proceeding in that 2D way.
Even if it ends up "working", it will take a ton of time and effort to set up and get it to solve, plus the physics will be wrong for multiple reasons
I would definitely just Model this in 3D.

Ash Kot · January 7, 2021, 15:43

Quote:

Originally Posted by Gert-Jan

Maybe the approach as described in the PhD thesis of Jasper Kelder from The Eindhoven University of Technology might help:

https://research.tue.nl/en/publicati...al-sterilisers

The whole Thesis is just 3D approach of Geometry, so the document didn't help me at all other than getting information of Food industry CFD stuff.

Gert-Jan · January 7, 2021, 16:10

Indeed, this thesis is all about 3D modelling, but it shows a nice simplification of a helical tube to a straight tube, which is easier to model. So if you want to model what is happening inside the tubes, this could be a valuable approach, even with a small computer, which I suspect you have, since you try to simplify things in a way that is useless as Evelica already mentioned.

Treating a heat exchanger with a helical tube in the way you want to, would not lead to meaning full results since you ignore the dean vortices that help the heat transfer.

If you are interested in what is happening outside the helical coil. then simply ignore these and model them as wall with a Neumann-Dirichlet boundary condition with temperature at infinitiy and a heat transfer coefficient.

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January 7, 2021, 10:32		#2
Gert-Jan Senior Member Gert-Jan Join Date: Oct 2012 Location: Europe Posts: 1,928 Rep Power: 28	Maybe the approach as described in the PhD thesis of Jasper Kelder from The Eindhoven University of Technology might help: https://research.tue.nl/en/publicati...al-sterilisers

January 7, 2021, 13:16		#3
evcelica Senior Member Erik Join Date: Feb 2011 Location: Earth (Land portion) Posts: 1,188 Rep Power: 23	I would not recommend proceeding in that 2D way. Even if it ends up "working", it will take a ton of time and effort to set up and get it to solve, plus the physics will be wrong for multiple reasons I would definitely just Model this in 3D.

January 7, 2021, 16:10		#5
Gert-Jan Senior Member Gert-Jan Join Date: Oct 2012 Location: Europe Posts: 1,928 Rep Power: 28	Indeed, this thesis is all about 3D modelling, but it shows a nice simplification of a helical tube to a straight tube, which is easier to model. So if you want to model what is happening inside the tubes, this could be a valuable approach, even with a small computer, which I suspect you have, since you try to simplify things in a way that is useless as Evelica already mentioned. Treating a heat exchanger with a helical tube in the way you want to, would not lead to meaning full results since you ignore the dean vortices that help the heat transfer. If you are interested in what is happening outside the helical coil. then simply ignore these and model them as wall with a Neumann-Dirichlet boundary condition with temperature at infinitiy and a heat transfer coefficient.