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-   -   Heat conduction and convection simulation (http://www.cfd-online.com/Forums/openfoam-solving/58211-heat-conduction-convection-simulation.html)

debashis December 15, 2008 11:18

hi all, I am trying to simula
 
hi all,
I am trying to simulate a very basic model, involving a solid heater over a solid block and a fluid flowing over the heater. I want to simulate the heat dissipation as conduction through the lower solid block and that as convection and conduction through the above fluid. I tried to solve it in 2D with only the fluid present and the heater & I am getting results, but when i am doing the 3D analysis, i am getting only the conduction results (straight heat distribution).... not the convection one, i.e. heat distribution (the heat flow bend) along flow direction..
Has anybody got similar problems before? Please let me know if u had so... Your help is highly appreciated...
Thanks in advance - Debashis Maji

debashis April 21, 2009 15:30

Hi.... please somebody help me with the above problem.... I am facing it yet again..... :o :mad: .......I am getting proper results of conduction but for convection i am not getting the heat flow distribution. Can anybody plz tell me whether there are any special settings for convection?.... any particular boundary condition?...
Thanking you in advance.....

kinghujun April 24, 2009 14:14

hi,
These days I also do some simulations on heat transfer, can you show me your boundry condition settings? or email me your mesh data, i really want to exchange some views with you on this question.
my email : kinghujun@163.com ;)

pathakamit September 12, 2012 00:58

Quote:

Originally Posted by debashis (Post 213707)
Hi.... please somebody help me with the above problem.... I am facing it yet again..... :o :mad: .......I am getting proper results of conduction but for convection i am not getting the heat flow distribution. Can anybody plz tell me whether there are any special settings for convection?.... any particular boundary condition?...
Thanking you in advance.....

We are simulating a simple heat transfer problem. The fins are supposed to enhance heat transfer from a plate. It consists of fins and air is being passed through them so as to cool them.

We guess that the design and mesh are correct, and perhaps we are not able to pre-define the problem. The description of our solving strategy is as follows:

1. Modelling in Pro-E

2. Importing in Ansys Workbench 14.0 Release, Fluid Flow (FLUENT)

3. DESIGN MODELLER: Creating Named Selections in Design Modeler, and specifying the domain as fluid and the fins as solid.

4. ANSYS MESH: Creating Fine Mesh with Default settings in Ansys Mesh.

5. FLUENT:

i. Creating Problem Setup: In Fluent

a) General: Pressure Based Solver, steady,

Model:

∑ Energy – ON

∑ Viscous-k-epsilon(Realizable)

b) Boundary Conditions:

∑ Giving an Inlet Velocity of 5m/sec at the inlet, and 300K air.

∑ Pressure Outlet is on by default.

∑ Heated Plate: Giving constant temperature of 723K

∑ Heat Generation Rate: 1000

∑ Heat transfer Coefficient: 210

∑ Mesh Interfaces: We defined interface connecting the interface domain and interface fins and we connected it by coupled wall.

ii. a) Solution Method:

Pressure Velocity Coupling: SIMPLE

b) Solution Initialization:

Solution Initialization: Standard Initialization(Compute From Inlet)

iii. c) Run Calculation:

No of iterations: 250

Results:
When we plot the contours, then we are getting pretty good contours as per our intuition of physical conditions but when we see the numerical values we are observing the air to leave at the same temp it enters.

MOREOVER WE HAVE USED THE SAME SETUP PROCEDURES, OF A WORK PREVIOUSLY DONE USING GAMBIT AND FLUENT 6.3, AND IN THAT WORK NO HEAT GENERATION RATE WAS GIVEN, STILL IT GAVE CORRECT RESULTS BUT IN OUR CASE WHEN WE DON’T GIVE THE HEAT GENERATION RATE (EVEN IF CHOOSE THE CONSTANT TEMPERATURE OPTION), THE PLATE COOLS DOWN.

So can anyone suggest the correct problem setup for the current case of heat transfer from a heated plate using fins.

This is the link for my problem case files, i.e. the ANSYS workbench files, using the same setup conditions, so anyone can check it out and tell the correct method.

https://www.dropbox.com/s/1csudpwioz...%20Problem.rar

OR CAN YOU SUGGEST ANY LINKS FOR SOME TUTORIAL OR VIDEOS, FOR THE CASE OF SIMPLE HEAT TRANSFER FROM A HEATED PLATE WITH FINS, SO THAT WE CAN LEARN HOW TO SET UP A HEAT TRANSFER PROBLEM FOR THE CASE OF FINS FIXED ON A HEATED PLATE.

pathakamit September 12, 2012 01:22

Quote:

Originally Posted by debashis (Post 213707)
Hi.... please somebody help me with the above problem.... I am facing it yet again..... :o :mad: .......I am getting proper results of conduction but for convection i am not getting the heat flow distribution. Can anybody plz tell me whether there are any special settings for convection?.... any particular boundary condition?...
Thanking you in advance.....

We are simulating a simple heat transfer problem. The fins are supposed to enhance heat transfer from a plate. It consists of fins and air is being passed through them so as to cool them.

We guess that the design and mesh are correct, and perhaps we are not able to pre-define the problem. The description of our solving strategy is as follows:

1. Modelling in Pro-E

2. Importing in Ansys Workbench 14.0 Release, Fluid Flow (FLUENT)

3. DESIGN MODELLER: Creating Named Selections in Design Modeler, and specifying the domain as fluid and the fins as solid.

4. ANSYS MESH: Creating Fine Mesh with Default settings in Ansys Mesh.

5. FLUENT:

i. Creating Problem Setup: In Fluent

a) General: Pressure Based Solver, steady,

Model:

∑ Energy Ė ON

∑ Viscous-k-epsilon(Realizable)

b) Boundary Conditions:

∑ Giving an Inlet Velocity of 5m/sec at the inlet, and 300K air.

∑ Pressure Outlet is on by default.

∑ Heated Plate: Giving constant temperature of 723K

∑ Heat Generation Rate: 1000

∑ Heat transfer Coefficient: 210

∑ Mesh Interfaces: We defined interface connecting the interface domain and interface fins and we connected it by coupled wall.

ii. a) Solution Method:

Pressure Velocity Coupling: SIMPLE

b) Solution Initialization:

Solution Initialization: Standard Initialization(Compute From Inlet)

iii. c) Run Calculation:

No of iterations: 250

Results:
When we plot the contours, then we are getting pretty good contours as per our intuition of physical conditions but when we see the numerical values we are observing the air to leave at the same temp it enters.

MOREOVER WE HAVE USED THE SAME SETUP PROCEDURES, OF A WORK PREVIOUSLY DONE USING GAMBIT AND FLUENT 6.3, AND IN THAT WORK NO HEAT GENERATION RATE WAS GIVEN, STILL IT GAVE CORRECT RESULTS BUT IN OUR CASE WHEN WE DONíT GIVE THE HEAT GENERATION RATE (EVEN IF CHOOSE THE CONSTANT TEMPERATURE OPTION), THE PLATE COOLS DOWN.

So can anyone suggest the correct problem setup for the current case of heat transfer from a heated plate using fins.

This is the link for my problem case files, i.e. the ANSYS workbench files, using the same setup conditions, so anyone can check it out and tell the correct method.

https://www.dropbox.com/s/1csudpwioz...%20Problem.rar

OR CAN YOU SUGGEST ANY LINKS FOR SOME TUTORIAL OR VIDEOS, FOR THE CASE OF SIMPLE HEAT TRANSFER FROM A HEATED PLATE WITH FINS, SO THAT WE CAN LEARN HOW TO SET UP A HEAT TRANSFER PROBLEM FOR THE CASE OF FINS FIXED ON A HEATED PLATE.

dineshkanthtp March 24, 2014 00:28

HT
 
How to calculate Heat transfer Coefficient for thermal analysis.Kindly please let me know


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