Menu

Discussion Forum

New Discussion
Filtrer

Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.

Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.

heat transfer in pipe flow

Posted 9 juin 2010, 03:16 UTC−4 Fluid & Heat, Heat Transfer & Phase Change, Computational Fluid Dynamics (CFD) Version 4.2 23 Replies

Ahmet Caglar
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

I have 1-m length copper tube with diameter 0.013 m, thickness 0.001 m and have heat transfer fluid passing through the tube. The inlet temperature of the fluid is 500 K. The flow velocity of the fluid is 0.05 m/s. The pipe is insulated. Initial conditions are default value of 273 K. When I work with 2D axial heat transfer module in transient condition, I draw two rectangles (half of the tube) one for fluid and the other for copper tube. When I enter the boundary conditions and subdomain settings and solve the model, I see that the temperature distribution is much more strange than I expect. I expect the temp. of hot oil is immediately transferred to the tube and temp. difference between the fluid and pipe is very small, let's say in the order of 10-20 K. However, the results give a very large temp. difference. Furthermore, for short times (when fluid flow is middle of the pipe 0.5 m) fluid temperature shows adsurd change at the end of flow. It increases up to 800-900 K which is not possible, and dicreases about 300 K. I don' t know what happens? I am looking for the mistake in boundary condition. At the horizontal contact boundary (contact between fluid and tube) comsol does not permit to enter a boundary condition in default. But I open the boundary interior boundaries option, it asks the hinf and Tinf. hinf is easy to enter but I don't know abut Tinf. Please can you help me about this? this is not, of course, my main purpose. I can not add any thing to my main project without doing this.
23 Replies Last Post 14 nov. 2011, 06:45 UTC−5
Andy Tomlinson
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 9 juin 2010, 10:01 UTC−4
Hi Ahmet,

Try this heat transfer model by creating "Identity/Contact pair" between the solid and fluid surfaces and by giving "Continuity" Boundary condition for the pair, so that it transfers heat between the two surfaces.

Regards,
AndyT
Hi Ahmet, Try this heat transfer model by creating "Identity/Contact pair" between the solid and fluid surfaces and by giving "Continuity" Boundary condition for the pair, so that it transfers heat between the two surfaces. Regards, AndyT
Ahmet Caglar
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 9 juin 2010, 11:29 UTC−4
Dear Andy
Very thanks for your interest. Then, how about the boundary conditions for individual two boundaries. Should both be heat flux having hinf and Tinf or covective flux or something else. The results obtained by creating a pair (I can not see identity/contact pair in Comsol 3.5, I just use create pairs in drawing mode) have some meaningful progress but not sufficient yet. Does your soln. includes the convective heat transfer in radial direction between solid and fluid? It does not ask h and Tdif (Tdif is temp diff. between tube wall and fluid) in applying continuity condition.



Hi Ahmet,

Try this heat transfer model by creating "Identity/Contact pair" between the solid and fluid surfaces and by giving "Continuity" Boundary condition for the pair, so that it transfers heat between the two surfaces.

Regards,
AndyT


Dear Andy Very thanks for your interest. Then, how about the boundary conditions for individual two boundaries. Should both be heat flux having hinf and Tinf or covective flux or something else. The results obtained by creating a pair (I can not see identity/contact pair in Comsol 3.5, I just use create pairs in drawing mode) have some meaningful progress but not sufficient yet. Does your soln. includes the convective heat transfer in radial direction between solid and fluid? It does not ask h and Tdif (Tdif is temp diff. between tube wall and fluid) in applying continuity condition. [QUOTE] Hi Ahmet, Try this heat transfer model by creating "Identity/Contact pair" between the solid and fluid surfaces and by giving "Continuity" Boundary condition for the pair, so that it transfers heat between the two surfaces. Regards, AndyT [/QUOTE]
Andy Tomlinson
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 10 juin 2010, 09:54 UTC−4
Hi Ahmet,
You can try doing this way - Go to Pairs (Boundary Settings - Pairs) and apply Continuity Boundary Condition for the Pair. Then go to Boundaries (Boundary Settings - Boundaries), it will show you 2 individual boundaries of the pair, select one on the fluid side and apply Heat Flux BC (Boundary Condition) by specifying 'h' and 'Tinf' (this is the Bulk temp. of the fluid). Then select another one on the solid side and give the same conditions as before and also enable Highly Conductive layer for this.
Then Solve it, see if this works.

Regards,
AndyT
Hi Ahmet, You can try doing this way - Go to Pairs (Boundary Settings - Pairs) and apply Continuity Boundary Condition for the Pair. Then go to Boundaries (Boundary Settings - Boundaries), it will show you 2 individual boundaries of the pair, select one on the fluid side and apply Heat Flux BC (Boundary Condition) by specifying 'h' and 'Tinf' (this is the Bulk temp. of the fluid). Then select another one on the solid side and give the same conditions as before and also enable Highly Conductive layer for this. Then Solve it, see if this works. Regards, AndyT
Meera Tetali
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 10 juin 2010, 17:20 UTC−4
Hello
This is meera , i am doing research on heat transfer in ceramic material when placed in center of microwave cavity (multimode cavity)
can you please help me in this topic.

Thanks
meera
Hello This is meera , i am doing research on heat transfer in ceramic material when placed in center of microwave cavity (multimode cavity) can you please help me in this topic. Thanks meera
Ahmet Caglar
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 13 juin 2010, 15:43 UTC−4
Hi Andy, Your suggestions seem to work. However, now there exists another problem. In this small-dia anf long-lenght pipe (radius and lenght of the pipe is 0.007 m and 0.75 m respectively), after a certain point along the pipe, temperature distribution of the fluid inside the pipe becomes very strange. It shows a behavior like a slug flow in fluid dynamics. After a certain distance from the starting of the flow, the temperature first increases over 500 K and then decreases about 300 K (initial temp. of the fluid and pipe) suddenly, and this wave oscillates between them. What may the problem be? Is there anybody who has any idea about that? Also although I select the bottom boundary as symmetry, temperature at this boundary decreases about 300 K after certain distance while it should be the hottest line (500 K or at least the highest in r direction) in the pipe. I don't know what happens at there? Could you please help me if you know?
Hi Andy, Your suggestions seem to work. However, now there exists another problem. In this small-dia anf long-lenght pipe (radius and lenght of the pipe is 0.007 m and 0.75 m respectively), after a certain point along the pipe, temperature distribution of the fluid inside the pipe becomes very strange. It shows a behavior like a slug flow in fluid dynamics. After a certain distance from the starting of the flow, the temperature first increases over 500 K and then decreases about 300 K (initial temp. of the fluid and pipe) suddenly, and this wave oscillates between them. What may the problem be? Is there anybody who has any idea about that? Also although I select the bottom boundary as symmetry, temperature at this boundary decreases about 300 K after certain distance while it should be the hottest line (500 K or at least the highest in r direction) in the pipe. I don't know what happens at there? Could you please help me if you know?
Robynne Murray
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 6 août 2010, 13:49 UTC−4
Hello,

I am having a similar problem. I have a very simple set up with aluminum and water, the water is flowing and is hotter than the Al, so heat should be transferred to the Al through the boundary. However, no heat is passing through. I have tried making a contact pair between the two surfaces, however there is only one edge that can be selected (the Al and water interface falls on the same line). I then use heat continuity under the heat transfer mode. Can anyone help me so that I can get heat flowing to the Al??

Thank you!!
Hello, I am having a similar problem. I have a very simple set up with aluminum and water, the water is flowing and is hotter than the Al, so heat should be transferred to the Al through the boundary. However, no heat is passing through. I have tried making a contact pair between the two surfaces, however there is only one edge that can be selected (the Al and water interface falls on the same line). I then use heat continuity under the heat transfer mode. Can anyone help me so that I can get heat flowing to the Al?? Thank you!!
comsol newbie
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 3 juin 2011, 01:37 UTC−4
Hi!

I am trying to model a pipeline of length 11.6 km with a known dia and thickness of metal wall and insulation thickness. The idea is to find the cooling power of the insulation fixing the outside temperature in one case and using the winds in the second case. For that i created a 3d using 3 concentric cylinders. Is the geometry right?Do i need to specify a control volume also.The problem i am facing is that the subdomain settings is coming deactivated in the physics menu and its not even being shown in the model tree. The same is for the boundary settings. What is the mistake here?

I'll be really glad if you could help me with this!
Hi! I am trying to model a pipeline of length 11.6 km with a known dia and thickness of metal wall and insulation thickness. The idea is to find the cooling power of the insulation fixing the outside temperature in one case and using the winds in the second case. For that i created a 3d using 3 concentric cylinders. Is the geometry right?Do i need to specify a control volume also.The problem i am facing is that the subdomain settings is coming deactivated in the physics menu and its not even being shown in the model tree. The same is for the boundary settings. What is the mistake here? I'll be really glad if you could help me with this!
Carlos Perez de la Blanca Castellano
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 8 nov. 2011, 06:56 UTC−5



Hi Anhmet,

I have just seen the problem you had time ago,and i would like to know if you can help me.

Im working in something similar,a heated fluid inside a pipe.Joined to this pipe there are fins that transfer the heat to a phase change material.

i achieved to make the fluid flow but my problem is relationated with his temperature.I want the fluid to enter at 573K and transfer the heat to the rest,so the temperature at the beginning should not be the same that the one at the end due to the heat losses.Instead of that i have a fluid flow at constant temperature of 573K and i dont want that.

Did you achieve to do that in your model???Can you give any advice or suggestion,i would be really grateful!!!!

Best regards,

Carlos
Hi Anhmet, I have just seen the problem you had time ago,and i would like to know if you can help me. Im working in something similar,a heated fluid inside a pipe.Joined to this pipe there are fins that transfer the heat to a phase change material. i achieved to make the fluid flow but my problem is relationated with his temperature.I want the fluid to enter at 573K and transfer the heat to the rest,so the temperature at the beginning should not be the same that the one at the end due to the heat losses.Instead of that i have a fluid flow at constant temperature of 573K and i dont want that. Did you achieve to do that in your model???Can you give any advice or suggestion,i would be really grateful!!!! Best regards, Carlos
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 8 nov. 2011, 10:15 UTC−5
Hi Carlos

Try to set your "initial value 2" temp at 300[K] for the fluid, and keep the inlet boundary at your high temperature, then change your time stepping "range(0,50,1000)" to "0,1 2 5 10 20 range(50,50,1000)"

You will then see the temperature of the fluid change over the first 3-4 seconds, thereafter, with your flow, the fluid temperature will be almost constant. Check the BIOT value for the different parts of your model

--
Good luck
Ivar
Hi Carlos Try to set your "initial value 2" temp at 300[K] for the fluid, and keep the inlet boundary at your high temperature, then change your time stepping "range(0,50,1000)" to "0,1 2 5 10 20 range(50,50,1000)" You will then see the temperature of the fluid change over the first 3-4 seconds, thereafter, with your flow, the fluid temperature will be almost constant. Check the BIOT value for the different parts of your model -- Good luck Ivar
Carlos Perez de la Blanca Castellano
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 8 nov. 2011, 10:39 UTC−5
Hi Ivar,

But that temperature change corresponds to the initial change temperature of the fluid(from 300K(initial value) to 573 K(temperature boundary condition)),isnt it?It should be like this at the beginning,may be,but after that,the temperature reached by the fluid should be less.,because its being heated by a "colder fluid"(not at 573K)

I mean,we can see how the initial fluid is heated until reach the maximum temperature but then,nothing happens,it remains at that temperature and it shouldnt be like this,isnt it?

Did i understand you???

Thank you for your time and for being helping me!!!

Best regards,

Carlos



ANOTHER THING:

I HAVE ALSO BEING SUGGESTED ABOUT USE "STEP FUNCTION"...WHAT DO YOU THINK???


Hi Ivar, But that temperature change corresponds to the initial change temperature of the fluid(from 300K(initial value) to 573 K(temperature boundary condition)),isnt it?It should be like this at the beginning,may be,but after that,the temperature reached by the fluid should be less.,because its being heated by a "colder fluid"(not at 573K) I mean,we can see how the initial fluid is heated until reach the maximum temperature but then,nothing happens,it remains at that temperature and it shouldnt be like this,isnt it? Did i understand you??? Thank you for your time and for being helping me!!! Best regards, Carlos ANOTHER THING: I HAVE ALSO BEING SUGGESTED ABOUT USE "STEP FUNCTION"...WHAT DO YOU THINK???
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 8 nov. 2011, 16:11 UTC−5
Hi

I believe you are getting fooled by the colors, you should chek the numerical values by integrating over the input and output, or make a temperature plot over the input/output boundaries

For the step function its often a good way to get a flow started, by ramping it gently with a continuous smooth function. But in your case, with a bundary mesh and a laminar inflow, I got the solver to converge quicly even without a step function, because you have a low flow rate

--
Good luck
Ivar
Hi I believe you are getting fooled by the colors, you should chek the numerical values by integrating over the input and output, or make a temperature plot over the input/output boundaries For the step function its often a good way to get a flow started, by ramping it gently with a continuous smooth function. But in your case, with a bundary mesh and a laminar inflow, I got the solver to converge quicly even without a step function, because you have a low flow rate -- Good luck Ivar
Carlos Perez de la Blanca Castellano
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 8 nov. 2011, 16:39 UTC−5


Hi Ivar,

Do you think the temperature plot is wronga nd the temperatures already changes?How can i do temperature plot over the imput/output boundaries as you said to check it?Im desperate with this!

Tomorrow i will also try the step function,both for the tempearure and for the velocity.

With this function,the velocity and the temperature will vary from 0 to the desirable value in a period of time,and then they will change but not due to this function(the fluid will dicrease the temperature due to heat losses) ¿?

Im not sure what i will achieve with this function!

Thanks you Ivar,you are helping me a lot!!
Hi Ivar, Do you think the temperature plot is wronga nd the temperatures already changes?How can i do temperature plot over the imput/output boundaries as you said to check it?Im desperate with this! Tomorrow i will also try the step function,both for the tempearure and for the velocity. With this function,the velocity and the temperature will vary from 0 to the desirable value in a period of time,and then they will change but not due to this function(the fluid will dicrease the temperature due to heat losses) ¿? Im not sure what i will achieve with this function! Thanks you Ivar,you are helping me a lot!!
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 9 nov. 2011, 03:43 UTC−5
Hi

from my experience there are very few "bugs" in COMSOL, but its easy to give wrong or incorrect input in multiphysics simulations. Your temperature plots are correct, but the automatic scale and graphical rendering can give you wrong impression on surface plots.

You can add a line plot and select a line along the inlet, then choose to plot the temperature the inflow velocity and the product of the density rho, heat capacity Cp times the temperature T times the velocity and you get the power influx W/m^2. The same for the outlet, and you can compare easier on 1D plots. To combine the two plots, you need to project the results from the inlet onto the outlet. Or you define global variables

--
Good luck
Ivar
Hi from my experience there are very few "bugs" in COMSOL, but its easy to give wrong or incorrect input in multiphysics simulations. Your temperature plots are correct, but the automatic scale and graphical rendering can give you wrong impression on surface plots. You can add a line plot and select a line along the inlet, then choose to plot the temperature the inflow velocity and the product of the density rho, heat capacity Cp times the temperature T times the velocity and you get the power influx W/m^2. The same for the outlet, and you can compare easier on 1D plots. To combine the two plots, you need to project the results from the inlet onto the outlet. Or you define global variables -- Good luck Ivar
Carlos Perez de la Blanca Castellano
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 9 nov. 2011, 07:33 UTC−5




Hi,

If i put the temperature in "intial value 2" at 493K,and the inlet temperature also at 493K,the temperature in the fins at the end of the simulation is different at the top than the tempearure fins at the bottom....so the fluid is loosing heat and is transferring less heat¿?but the tempearure fluid seems to be the same in all the pipe

I dont know what to think,you think is correct,but how can i do Comsol plot it right??

I attached the file
Hi, If i put the temperature in "intial value 2" at 493K,and the inlet temperature also at 493K,the temperature in the fins at the end of the simulation is different at the top than the tempearure fins at the bottom....so the fluid is loosing heat and is transferring less heat¿?but the tempearure fluid seems to be the same in all the pipe I dont know what to think,you think is correct,but how can i do Comsol plot it right?? I attached the file
Lechoslaw Krolikowski
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 9 nov. 2011, 12:40 UTC−5
Hi,

I've run your simulation. It looks fine. See attached files. Animation shows how heat penetrates from water to aluminium and SS. Plot of average outflow temperature vs time shows that water loses heat.

Regards,
Andrzej
Hi, I've run your simulation. It looks fine. See attached files. Animation shows how heat penetrates from water to aluminium and SS. Plot of average outflow temperature vs time shows that water loses heat. Regards, Andrzej
Carlos Perez de la Blanca Castellano
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 9 nov. 2011, 13:01 UTC−5
Hi Andrzej,

That you for looking my model.

I dont understand.Looking at the plot Av-Out vs T,i see that the temperature of the fluid increases until 493K,so its not loosing heat,and in the other plot the entire pipe its at the same color.The fluid temperature at the end should be inferior than 493K,isnt it?

Could you explain me?

Thanks,

Best regards,

Carlos

AND HOW DID YOU DO THE OUTvsT PLOT??Thanks
Hi Andrzej, That you for looking my model. I dont understand.Looking at the plot Av-Out vs T,i see that the temperature of the fluid increases until 493K,so its not loosing heat,and in the other plot the entire pipe its at the same color.The fluid temperature at the end should be inferior than 493K,isnt it? Could you explain me? Thanks, Best regards, Carlos AND HOW DID YOU DO THE OUTvsT PLOT??Thanks
Lechoslaw Krolikowski
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 9 nov. 2011, 16:14 UTC−5
Hi,

In the limit, when time tends to infinity, the temperature tends to 493K (inflow temp.) in all domains and the rate of heat transfer goes to 0. Under these conditions (steady state) the outflow temp. is equal to the inflow temp.

How to get the plot of average outflow temp. vs time?
Under the Results node right-click Derived Values. Choose Average > Line Average. Line Average window appears. Under Selection choose boundary 28. Click = icon (evaluate icon). In the Results window (right-bottom corner) click Plot icon.

Regards,
Andrzej
Hi, In the limit, when time tends to infinity, the temperature tends to 493K (inflow temp.) in all domains and the rate of heat transfer goes to 0. Under these conditions (steady state) the outflow temp. is equal to the inflow temp. How to get the plot of average outflow temp. vs time? Under the Results node right-click Derived Values. Choose Average > Line Average. Line Average window appears. Under Selection choose boundary 28. Click = icon (evaluate icon). In the Results window (right-bottom corner) click Plot icon. Regards, Andrzej
Carlos Perez de la Blanca Castellano
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 9 nov. 2011, 17:01 UTC−5
Hi Andrzej,

Thank you very much for your answer,again!

Why do the domains tend to 493K if the intial value is 493K??They have a flow entering at 493K also,so at the beginning,the outflow temperature should be the same that the inlet temperature,but after the time simulation,it shouldnt be like that,the entering flow should have dicrease his temperature due to it has transferred heat to the rest.......SORRY for my clumsiness!!!!!I just want to simulate the heat transferred by a fluid that enters at that temperature...do you think is already achieved?

Why is not that reflected in the temperature plot???The fluid should have different colors(less temperature)at the end!!!

Sorry again,i hope to understand what you mean

Best regards,

Thank you for your time,really!!!

Carlos

CAN I DO A PLOT "OUTFLOW TEMPERATURE vs TIME" or it doesnt have sense?
Hi Andrzej, Thank you very much for your answer,again! Why do the domains tend to 493K if the intial value is 493K??They have a flow entering at 493K also,so at the beginning,the outflow temperature should be the same that the inlet temperature,but after the time simulation,it shouldnt be like that,the entering flow should have dicrease his temperature due to it has transferred heat to the rest.......SORRY for my clumsiness!!!!!I just want to simulate the heat transferred by a fluid that enters at that temperature...do you think is already achieved? Why is not that reflected in the temperature plot???The fluid should have different colors(less temperature)at the end!!! Sorry again,i hope to understand what you mean Best regards, Thank you for your time,really!!! Carlos CAN I DO A PLOT "OUTFLOW TEMPERATURE vs TIME" or it doesnt have sense?
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 10 nov. 2011, 01:27 UTC−5
Hi Carlos

take a look, you have a flow of 0.5 m/s your device is only 0.45m long, then you look at the temperature after 50 seconds, the fluid has passed 100x the length of your device, that is why the fluid appear at more or less constant temperature. Try a stepping time much shorterr at the beginning like 0.1 0.5 1 2 seconds and you will see better effects. By the way have you checked your mesh size, time stepping, heat diffucivity and heat capaciyt time constants, and their coherence across your model ?. Chekc a book on the Biot number and the time constants for yout thermal analysis, as well as the fluid Renolds, Prandtl and Nusselt number, all these are also useful to check the validity of your model settings

--
Good luck
Ivar
Hi Carlos take a look, you have a flow of 0.5 m/s your device is only 0.45m long, then you look at the temperature after 50 seconds, the fluid has passed 100x the length of your device, that is why the fluid appear at more or less constant temperature. Try a stepping time much shorterr at the beginning like 0.1 0.5 1 2 seconds and you will see better effects. By the way have you checked your mesh size, time stepping, heat diffucivity and heat capaciyt time constants, and their coherence across your model ?. Chekc a book on the Biot number and the time constants for yout thermal analysis, as well as the fluid Renolds, Prandtl and Nusselt number, all these are also useful to check the validity of your model settings -- Good luck Ivar
Lechoslaw Krolikowski
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 10 nov. 2011, 11:09 UTC−5

Why do the domains tend to 493K if the intial value is 493K??
CAN I DO A PLOT "OUTFLOW TEMPERATURE vs TIME" or it doesnt have sense?


Hi,

Initial temperature of Al+SS domains is 293K as you can see in Prueba Conjugate HT.mph.
Hot water of the constant temperature 493K flows into your system. All outer boundaries (exept inlet and outlet) are insulated. Therefore, the final temperature of all domains (H2O+Al+SS) must be 493K irrespective of the initial temperature.

Outflow temperature Tout is a function of the two variables: t (time) and x-coordinate. You can plot Tout vs t fixing x or
Tout vs x fixing t.

Regards,
Andrzej

[QUOTE] Why do the domains tend to 493K if the intial value is 493K?? CAN I DO A PLOT "OUTFLOW TEMPERATURE vs TIME" or it doesnt have sense? [/QUOTE] Hi, Initial temperature of Al+SS domains is 293K as you can see in Prueba Conjugate HT.mph. Hot water of the constant temperature 493K flows into your system. All outer boundaries (exept inlet and outlet) are insulated. Therefore, the final temperature of all domains (H2O+Al+SS) must be 493K irrespective of the initial temperature. Outflow temperature Tout is a function of the two variables: t (time) and x-coordinate. You can plot Tout vs t fixing x or Tout vs x fixing t. Regards, Andrzej
Carlos Perez de la Blanca Castellano
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 10 nov. 2011, 12:39 UTC−5


Hi Andrzej,


Today i made a 3D simulation with a fluid putting the same boundary condition(TEMPERATURE and INLET).The fluid looses temperature,so i think the design should be ok,as you said!

I will try to make the plots,i will tell you if i can!

Thank very much for your time!

Best regards,

Carlos
Hi Andrzej, Today i made a 3D simulation with a fluid putting the same boundary condition(TEMPERATURE and INLET).The fluid looses temperature,so i think the design should be ok,as you said! I will try to make the plots,i will tell you if i can! Thank very much for your time! Best regards, Carlos
Carlos Perez de la Blanca Castellano
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 10 nov. 2011, 12:45 UTC−5


Hi Ivar,

You were also right,the water looses temperature,i have seen it in a 3D simulation with the same boundary condition,but not in 2D.


Where can i check all these parameters??

Thank you very much for your time and help!!!

Best regards,

Carlos
Hi Ivar, You were also right,the water looses temperature,i have seen it in a 3D simulation with the same boundary condition,but not in 2D. Where can i check all these parameters?? Thank you very much for your time and help!!! Best regards, Carlos
Carlos Perez de la Blanca Castellano
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 14 nov. 2011, 06:45 UTC−5



Ivar,is there any way to make a fluid flows in close circuit(self circulating)?I have a close circuit of pipes,one of the part of the circuit is exposed to heat flux and i would like to see the velocity,temperature..

Any suggestion?

Thanks,

Carlos
Ivar,is there any way to make a fluid flows in close circuit(self circulating)?I have a close circuit of pipes,one of the part of the circuit is exposed to heat flux and i would like to see the velocity,temperature.. Any suggestion? Thanks, Carlos

Note that while COMSOL employees may participate in the discussion forum, COMSOL® software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team.

Suggested Content