heat transfer screws

Martin_Sz · May 25, 2015, 07:11

Hello
I have to model a heat transfer on the steel screws. How to simplify and model this problem. The black cube is filled with screws. Green cube is a fluid domain. On the top and the bottom wall I have temperature 700 C.
Initialization
Fluid domain 20 C
screws 20 C.
Transient analysis - 9 hours.
How to model black domain ??
Porosity, multiphase, particle tracking ??
Best regards from poland

JuPa · May 25, 2015, 09:05

Model the thousands of screws as a porous medium.

Martin_Sz · May 26, 2015, 02:09

Thanks
And how to determine interfacial loss coefficient ??

Martin_Sz · May 26, 2015, 02:11

sorry
interfacial area density ??

JuPa · May 26, 2015, 07:25

Why do you need the interfacial area density? This is a single phase simulation isn't it?

Regarding loss coefficients: they can be found in text books to start with.

Martin_Sz · May 29, 2015, 01:12

thanks for Your answer
I define porous domain. Everything is good when I define heat transfer between
fluid domain and porous.
But when i define velocity from left wall to right wall (fluid domain) imbalances go high and after couple time steps i get error overflow.
What I do wrong??
Best regards

singer1812 · May 29, 2015, 10:09

Did you try increasing your Source Coefficient?
Is it large to begin with?

Martin_Sz · May 30, 2015, 02:26

Hello
What do You mean ??
I have another questions
below interface area density is heat transfer coefficient
can i take value form previous simuation with one screw which I determine to 2
W/m2K?? And what about heat transfer on solid? Can Ileave adiabatic ??
Best regards

Martin_Sz · May 30, 2015, 02:30

so when air with defined velocity going into porous domain all imbalances goes high and after couple timesteps I get error overflow
Anyone knew any tutorials with immersed porous medium like in my case ??

Martin_Sz · June 1, 2015, 02:08

Can anyone help me ??

singer1812 · June 2, 2015, 08:32

Look up Source Coefficient in CFX help. I briefly looked over your post and it seems like this could help you.
Take a look, and ask more questions after. If you need more help, describe your problem more, and perhaps post some pics of your setup and settings.

Martin_Sz · July 22, 2015, 05:48

thanks a lot of your answers

Martin_Sz · July 23, 2015, 08:37

can anyone tutorials for porous medium with heat transfer but immersed (all walls) on the fluid domain ??

July 22, 2015, 05:48		#12
Martin_Sz Senior Member Marcin Join Date: May 2014 Location: Poland, Swiebodzin Posts: 232 Rep Power: 12	thanks a lot of your answers __________________ Quick Tips and Tricks, Tutorials FLuent/ CFX (CFD) https://howtooansys.blogspot.com/

July 23, 2015, 08:37		#13
Martin_Sz Senior Member Marcin Join Date: May 2014 Location: Poland, Swiebodzin Posts: 232 Rep Power: 12	can anyone tutorials for porous medium with heat transfer but immersed (all walls) on the fluid domain ?? __________________ Quick Tips and Tricks, Tutorials FLuent/ CFX (CFD) https://howtooansys.blogspot.com/

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May 25, 2015, 09:05		#2
JuPa Senior Member Mr CFD Join Date: Jun 2012 Location: Britain Posts: 361 Rep Power: 14	Model the thousands of screws as a porous medium.

May 26, 2015, 02:09		#3
Martin_Sz Senior Member Marcin Join Date: May 2014 Location: Poland, Swiebodzin Posts: 232 Rep Power: 12	Thanks And how to determine interfacial loss coefficient ??

May 26, 2015, 02:11		#4
Martin_Sz Senior Member Marcin Join Date: May 2014 Location: Poland, Swiebodzin Posts: 232 Rep Power: 12	sorry interfacial area density ??

May 26, 2015, 07:25		#5
JuPa Senior Member Mr CFD Join Date: Jun 2012 Location: Britain Posts: 361 Rep Power: 14	Why do you need the interfacial area density? This is a single phase simulation isn't it? Regarding loss coefficients: they can be found in text books to start with.

May 29, 2015, 01:12		#6
Martin_Sz Senior Member Marcin Join Date: May 2014 Location: Poland, Swiebodzin Posts: 232 Rep Power: 12	thanks for Your answer I define porous domain. Everything is good when I define heat transfer between fluid domain and porous. But when i define velocity from left wall to right wall (fluid domain) imbalances go high and after couple time steps i get error overflow. What I do wrong?? Best regards

May 29, 2015, 10:09		#7
singer1812 Senior Member Edmund Singer P.E. Join Date: Aug 2010 Location: Minneapolis, MN Posts: 511 Rep Power: 20	Did you try increasing your Source Coefficient? Is it large to begin with?

May 30, 2015, 02:26		#8
Martin_Sz Senior Member Marcin Join Date: May 2014 Location: Poland, Swiebodzin Posts: 232 Rep Power: 12	Hello What do You mean ?? I have another questions below interface area density is heat transfer coefficient can i take value form previous simuation with one screw which I determine to 2 W/m2K?? And what about heat transfer on solid? Can Ileave adiabatic ?? Best regards

May 30, 2015, 02:30		#9
Martin_Sz Senior Member Marcin Join Date: May 2014 Location: Poland, Swiebodzin Posts: 232 Rep Power: 12	so when air with defined velocity going into porous domain all imbalances goes high and after couple timesteps I get error overflow Anyone knew any tutorials with immersed porous medium like in my case ??

June 1, 2015, 02:08		#10
Martin_Sz Senior Member Marcin Join Date: May 2014 Location: Poland, Swiebodzin Posts: 232 Rep Power: 12	Can anyone help me ??

June 2, 2015, 08:32		#11
singer1812 Senior Member Edmund Singer P.E. Join Date: Aug 2010 Location: Minneapolis, MN Posts: 511 Rep Power: 20	Look up Source Coefficient in CFX help. I briefly looked over your post and it seems like this could help you. Take a look, and ask more questions after. If you need more help, describe your problem more, and perhaps post some pics of your setup and settings.