# Laminar , steady state pipe flow

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 April 3, 2013, 03:29 #21 Member   B T KANNAN Join Date: Jul 2011 Location: CHENNAI (MADRAS), INDIA Posts: 54 Rep Power: 6 Dear Vishal,We are assuming wedge as an approximation to simplify the domain. Radius is R {because R*0.999 is approximately equals R only right ??} -- KANNAN

April 4, 2013, 00:15
#22
Senior Member

Vishal Nandigana
Join Date: Mar 2009
Location: Champaign, Illinois, U.S.A
Posts: 207
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Quote:
 Originally Posted by skyinventorbt Dear Vishal,We are assuming wedge as an approximation to simplify the domain. Radius is R {because R*0.999 is approximately equals R only right ??} -- KANNAN
You are right :P... was just curious why it was thought about to construct the geometry in this manner . The geometry works fine. Thanks for your tips.

April 5, 2013, 14:16
#23
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Vishal Nandigana
Join Date: Mar 2009
Location: Champaign, Illinois, U.S.A
Posts: 207
Rep Power: 9
Quote:
 Originally Posted by nandiganavishal You are right :P... was just curious why it was thought about to construct the geometry in this manner . The geometry works fine. Thanks for your tips.
Hi Kanan,

I am now modeling a concentric pipe geometry. I have difficulty in understanding which faces I should generate the mesh. I would like to give boundary conditions on both the surface of inner pipe and on the outer pipe. Here is the sample blockmesh dict file that I have generated.

// length of pore = 36 nm and diameter: 10.2nm , theta = 2 deg (consider this as outer pipe)
// length of DNA = 36 nm and diameter of DNA: 2.2nm , theta = 2 deg (consider this as inner pipe)
//r_DNA*cos(theta/2) = 1.1*cos(0.0349/2 radians) = 1.0998
// r_DNA*sin(theta/2) = 1.1*sin(0.0349/2 radians) = 0.0192
//r_pore*cos(theta/2) = 5.1*cos(0.0349/2 radians) = 5.0992
//r_pore*sin(theta/2) = 5.1*sin(0.0349/2 radians) = 0.0890
vertices
(
(0 0 0) // vertex 0
(36 0 0) // vertex 1
(36 1.0998 -0.0192) // vertex 2 (L,r_DNA*cos(theta/2),-r_DNA*sin(theta/2))
(0 1.0998 -0.0192) // vertex 3 (0,rcos(theta/2),-rsin(theta/2))
(36 5.0992 -0.0890) // vertex 4 (L,r_pore*cos(theta/2),-r_pore*sin(theta/2))
(0 5.0992 -0.0890) // vertex 5 (0,r_pore*cos(theta/2),-r_pore*sin(theta/2))

(0 0 0.0192) // vertex 6 (0, 0,r_DNA*sin(theta/2))
(36 0 0.0192) // vertex 7 (L, 0,r_DNA*sin(theta/2))
(36 1.0998 0.0192) // vertex 8 (0, r_DNA*cos(theta/2),r_DNA*sin(theta/2))
(0 1.0998 0.0192) // vertex 9 (L, r_DNA*cos(theta/2),r_DNA*sin(theta/2))
(0 0 0.0890) // vertex 10 (0, 0,r_pore*sin(theta/2))
(36 0 0.0890) // vertex 11 (L, 0,r_pore*sin(theta/2))
(36 5.0992 0.0890) // vertex 12 (L,r_pore*cos(theta/2),r_pore*sin(theta/2))
(0 5.0992 0.0890) // vertex 13 (0,r_pore*cos(theta/2),r_pore*sin(theta/2))
);

Please let me know if the vertices are correct. If so, how to generate the mesh for the same.

Thanks

Regards
Vishal

 February 23, 2015, 11:30 #24 Member   Naresh Yathuru Join Date: Feb 2015 Posts: 54 Rep Power: 2 hi thanks every one for posting the reply. i have a question i would like to simulate a steady state simulate in ico foam so i changed to ddtScheme { type steadystate; } Then i got this error FOAM Warning : From function gaussConvectionScheme in file finiteVolume/convectionSchemes/gaussConvectionScheme/gaussConvectionScheme.H at line 123 Reading "/home/yathuru/task1steady/system/fvSchemes.divSchemes.div(phi,U)" at line 31 Unbounded 'Gauss' div scheme used in steady-state solver, use 'bounded Gauss' to ensure boundedness. To remove this warning switch off 'boundedGauss' in "/opt/OpenFOAM-2.3.0/etc/controlDict". can some one help me.. i m lost.

 February 23, 2015, 11:59 #25 Senior Member     Jose Luis Santos Join Date: Mar 2009 Location: Portugal Posts: 213 Rep Power: 9 Hi, icoFoam is a transient solver. If you need steady state, simpleFoam is probably what you need. Regards, Jose

February 25, 2015, 06:57
#26
Senior Member

Tushar Chourushi
Join Date: Jul 2009
Location: IIT-Indore, India
Posts: 319
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Quote:
 Originally Posted by Naresh yathuru hi thanks every one for posting the reply. i have a question i would like to simulate a steady state simulate in ico foam so i changed to ddtScheme { type steadystate; } Then i got this error FOAM Warning : From function gaussConvectionScheme in file finiteVolume/convectionSchemes/gaussConvectionScheme/gaussConvectionScheme.H at line 123 Reading "/home/yathuru/task1steady/system/fvSchemes.divSchemes.div(phi,U)" at line 31 Unbounded 'Gauss' div scheme used in steady-state solver, use 'bounded Gauss' to ensure boundedness. To remove this warning switch off 'boundedGauss' in "/opt/OpenFOAM-2.3.0/etc/controlDict". can some one help me.. i m lost.
Dear Naresh,

It's just a warning I guess you can run your case with that.

OR, you can remove the warning as follows:

Code:
```divSchemes
{
... bounded Gauss upwind;
...
}```
-
Best Regards!
__________________
Mistakes Are Inevitable, You Can Only Grow Stronger If You Lean From Them

 March 2, 2015, 05:03 #27 Member   Naresh Yathuru Join Date: Feb 2015 Posts: 54 Rep Power: 2 Thank you so much for your reply santos and tushar. I knew i can do it in simple foam but just out of curiosity i wanted to try it in ico foam. I ran the simulation in simple foam its working well then i changed the case to turbulent simulation its is also working well now. however i have some issues with the convergence. i will try to figure it out. if not i will get back again .

March 2, 2015, 06:42
#28
Senior Member

Tushar Chourushi
Join Date: Jul 2009
Location: IIT-Indore, India
Posts: 319
Blog Entries: 1
Rep Power: 9
Quote:
 Originally Posted by Naresh yathuru Thank you so much for your reply santos and tushar. I knew i can do it in simple foam but just out of curiosity i wanted to try it in ico foam... .
Dear Naresh,

Please refer my previous post again. I said that you can run your icofoam solver using the steady state command. Anyways I am writing these again:

Code:
```ddtScheme
{
type steadystate;
}

divSchemes
{
div(phi,U) bounded Gauss upwind;
...
}```
Best Luck!
__________________
Mistakes Are Inevitable, You Can Only Grow Stronger If You Lean From Them

 March 2, 2015, 11:17 #29 Member   Naresh Yathuru Join Date: Feb 2015 Posts: 54 Rep Power: 2 Thanks once again Tushar. I m afraid if i can post this question here. could you please give me some tips for which solver to use for this case below: Geometry : a room with a box inside. the room has a inlet and outlet. I want to simulate the flow through this room with some velocity and temperature at the inlet, the roof is maintained at a low temperature (20 C) and the box inside is maintained at a temperature (35C). could you please suggest a solver.

March 3, 2015, 00:11
#30
Senior Member

Tushar Chourushi
Join Date: Jul 2009
Location: IIT-Indore, India
Posts: 319
Blog Entries: 1
Rep Power: 9
Quote:
 Originally Posted by Naresh yathuru Thanks once again Tushar. I m afraid if i can post this question here. could you please give me some tips for which solver to use for this case below: Geometry : a room with a box inside. the room has a inlet and outlet. I want to simulate the flow through this room with some velocity and temperature at the inlet, the roof is maintained at a low temperature (20 C) and the box inside is maintained at a temperature (35C). could you please suggest a solver.
Dear Naresh,

I will prefer you to go for "BuoyantBoussinesqPisoFoam", this will do the job. Wish you Good Luck for your work.

-
Best Regards!
__________________
Mistakes Are Inevitable, You Can Only Grow Stronger If You Lean From Them

 March 3, 2015, 03:12 #31 Member   Naresh Yathuru Join Date: Feb 2015 Posts: 54 Rep Power: 2 Thank you once again for your continuous support. U have no idea how much this tipp mean to me. thanks.

March 3, 2015, 03:42
#32
Senior Member

Tushar Chourushi
Join Date: Jul 2009
Location: IIT-Indore, India
Posts: 319
Blog Entries: 1
Rep Power: 9
Quote:
 Originally Posted by Naresh yathuru Thank you once again for your continuous support. U have no idea how much this tipp mean to me. thanks.
Welcome

-
Best Luck!
__________________
Mistakes Are Inevitable, You Can Only Grow Stronger If You Lean From Them

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