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how to couple two different physics?

Posted 11 nov. 2013, 05:02 UTC−5 Low-Frequency Electromagnetics, Plasma Physics, RF & Microwave Engineering Version 5.1 9 Replies

Anup Paul
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Hi
Dear friend

I am using Physics "Transient heat diffusion equation in solid" to calculate T(x,y,z,t).
Now another Physics "Distributed ODEs and DAEs(dode)" is used to write the following equation:

dX/dt=(A)*[exp{-E/RT}]

where
A, E & R=constant
T(x,y,z,t)=variable [obtained after solving Physics "Transient heat diffusion equation in solid"]
t= time
x,y,z= space coordinate

want to solve to find out X(x,y,z,t).............
I got a problem here, as i have mentioned, equation contains three variable:

The temperature T is obtained after solving a "Transient heat diffusion equation in solid Physics" and is used as the input to the ODE. That means the two physics "Transient heat diffusion equation in solid Physics" AND "Distributed ODEs and DAEs(dode) Physics" should be coupled together since I need the value of T(x,y,z,t) to calculate X (x, y,z,t).


Can anyone please tell me, how to couple these two physics in COMSOL 4.2??


regards


Anup
9 Replies Last Post 7 mars 2017, 03:28 UTC−5
Alberto Garcia-Cristobal
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Posted: 1 decade ago 11 nov. 2013, 05:40 UTC−5
Hi

What you have to do is,

1-create two studies one for "Transient heat diffusion equation in solid" (Study 1) and other for PDE (Study 2). in the study-2 you put the parameter you want use from study one...in u case 'T"

2- after this go to ' study two'......> 'dependent variable' you will get option 'Values of Variables Not Solved For' then take the following options...


-Method......>solutions
Solution.....> solver one
-selection.....> automatic
out put ....> initial ....

at this stage the any result from study one can be used in study-2.

for more information read the following note from the help section. search for 'Dependent Variables' in the
help....> dynamic help.... section

Hi What you have to do is, 1-create two studies one for "Transient heat diffusion equation in solid" (Study 1) and other for PDE (Study 2). in the study-2 you put the parameter you want use from study one...in u case 'T" 2- after this go to ' study two'......> 'dependent variable' you will get option 'Values of Variables Not Solved For' then take the following options... -Method......>solutions Solution.....> solver one -selection.....> automatic out put ....> initial .... at this stage the any result from study one can be used in study-2. for more information read the following note from the help section. search for 'Dependent Variables' in the help....> dynamic help.... section
Anup Paul
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Posted: 1 decade ago 11 nov. 2013, 08:23 UTC−5
Dear Alberto

thanks

But I could not understand step-1 u have mentioned

1-create two studies one for "Transient heat diffusion equation in solid" (Study 1) and other for PDE (Study 2). in the study-2 you put the parameter you want use from study one...in u case 'T"



thanks
Dear Alberto thanks But I could not understand step-1 u have mentioned 1-create two studies one for "Transient heat diffusion equation in solid" (Study 1) and other for PDE (Study 2). in the study-2 you put the parameter you want use from study one...in u case 'T" thanks
ComsolRaff
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Posted: 1 decade ago 11 nov. 2013, 08:43 UTC−5
You have 2 different physics.
Alberto says that you can create 2 studies.
If you click on study 1, you can set in Step 1 to solve only the temperature physic, putting the X symbol on the other one.
In Study 2, Step 2 expand the "Values of dependent variables" submenu and set it as Alberto suggests.

You have 2 different physics. Alberto says that you can create 2 studies. If you click on study 1, you can set in Step 1 to solve only the temperature physic, putting the X symbol on the other one. In Study 2, Step 2 expand the "Values of dependent variables" submenu and set it as Alberto suggests.
Anup Paul
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Posted: 1 decade ago 11 nov. 2013, 09:14 UTC−5
hi

Actually I am new to this software.

I am explaining below how i am trying to solve:

Step-1:
Selecting two physics "Heat Transfer (study 1)" and "Distributed ODE & DAEs (Study 2)"
Step-2:
Draw the geometry
Step-3:
Defining material
Step-4:
Meshing
Step-5:
Defining boundary conditions for physics "Heat Transfer (study 1)"
Step-6:
In Study-1 only one thing is mentioned i.e., "Time Dependent". No other links are available
Here, I am defining the time step and the total solution time
Step-7:
Then I compute it for getting T(x,y,z.t)
Step-8:
Now, I move to study-2 there also only one link is given i.e., "Time Dependent"
so I follow the step-6

Solution:

I am getting expected T(x,y,z,t), but not the other variable.



rgds

Anup
hi Actually I am new to this software. I am explaining below how i am trying to solve: Step-1: Selecting two physics "Heat Transfer (study 1)" and "Distributed ODE & DAEs (Study 2)" Step-2: Draw the geometry Step-3: Defining material Step-4: Meshing Step-5: Defining boundary conditions for physics "Heat Transfer (study 1)" Step-6: In Study-1 only one thing is mentioned i.e., "Time Dependent". No other links are available Here, I am defining the time step and the total solution time Step-7: Then I compute it for getting T(x,y,z.t) Step-8: Now, I move to study-2 there also only one link is given i.e., "Time Dependent" so I follow the step-6 Solution: I am getting expected T(x,y,z,t), but not the other variable. rgds Anup
Alberto Garcia-Cristobal
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Posted: 1 decade ago 11 nov. 2013, 10:51 UTC−5
Its so easy just read the note from the help. type ' dependent variable' in the dynamic help section

1-- help
2- dynamic...
3- search
4- type 'dependent variable'



Its so easy just read the note from the help. type ' dependent variable' in the dynamic help section 1-- help 2- dynamic... 3- search 4- type 'dependent variable'
Anup Paul
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Posted: 1 decade ago 12 nov. 2013, 03:48 UTC−5
Dear Alberto

Thanks a lot.......
Dear Alberto Thanks a lot.......
sevima
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Posted: 8 years ago 18 nov. 2016, 03:42 UTC−5
hello,

I have the same problem. The only thing is I can not define the T for both physics. I have a T in heat transfer module and a T2 in a PDE eqn that I have built. The comsol doesn't let me have same variable in both of them. so, How can I solve this?! how can I relate the T2 to T?!

Thanks a lot
hello, I have the same problem. The only thing is I can not define the T for both physics. I have a T in heat transfer module and a T2 in a PDE eqn that I have built. The comsol doesn't let me have same variable in both of them. so, How can I solve this?! how can I relate the T2 to T?! Thanks a lot
Hamdoun Sabrina
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Posted: 8 years ago 15 févr. 2017, 08:20 UTC−5

1-create two studies one for "Transient heat diffusion equation in solid" (Study 1) and other for PDE (Study 2). in the study-2 you put the parameter you want use from study one...in u case 'T"


Hi, please, can you tell me how put the parameter in the study 2 ? in the boundary condition, or in the solver ?
[QUOTE] 1-create two studies one for "Transient heat diffusion equation in solid" (Study 1) and other for PDE (Study 2). in the study-2 you put the parameter you want use from study one...in u case 'T" [/QUOTE] Hi, please, can you tell me how put the parameter in the study 2 ? in the boundary condition, or in the solver ?
Yasmien Abd El Hak
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Posted: 8 years ago 7 mars 2017, 03:28 UTC−5
Hi Hamdoun

Do you get an answer for your question, the proper place to put parameter T in study 2
Hi Hamdoun Do you get an answer for your question, the proper place to put parameter T in study 2

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