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.
Variable/constant heat over specific time periods
Posted Oct 27, 2015, 11:15 a.m. EDT Heat Transfer & Phase Change, Parameters, Variables, & Functions 2 Replies
Please login with a confirmed email address before reporting spam
Hi,
I am obviously quite new to COMSOL, and I have a question regarding time dependent variables.
I have constructed a very easy cable (conductor and insulation) with a constant temperature on the outer surface of the cable. The heat produced in the conductor is sat as a "Heat source" from the "Heat transfer in solids" interface. I Have defined the heat as P=I^2*R, where both P, I and R are defined in "parameters" as constant values. The simulations looks good, and the results are just as expected. This is under a time dependent simulation, where the time runs from 0 to 4 hours. Steady state temperatures are achieved after aprox. 3 hours. So far, so good.
Now, i want to run a simulation where the current (I) is a variable in time. This could for example be something like this:
0 hour to 1 hour --> current = 0.8*I
1 hour to 2 hour --> current = 1.2*I
2 hours to 3 hours --> current =1.6*I
3 hours to 4 hours --> current =0.6*I etc.
I have tried to use the piecewise-function, but i don`t undertand how to implement it to the simulations. I have also tried the parametric sweep, but it made no sense. Obviously, I would like to plot the temperature as a function of time, and the current as a function of time, and finally compare them.
How can I solve this?
Best Regards,
Tord
I am obviously quite new to COMSOL, and I have a question regarding time dependent variables.
I have constructed a very easy cable (conductor and insulation) with a constant temperature on the outer surface of the cable. The heat produced in the conductor is sat as a "Heat source" from the "Heat transfer in solids" interface. I Have defined the heat as P=I^2*R, where both P, I and R are defined in "parameters" as constant values. The simulations looks good, and the results are just as expected. This is under a time dependent simulation, where the time runs from 0 to 4 hours. Steady state temperatures are achieved after aprox. 3 hours. So far, so good.
Now, i want to run a simulation where the current (I) is a variable in time. This could for example be something like this:
0 hour to 1 hour --> current = 0.8*I
1 hour to 2 hour --> current = 1.2*I
2 hours to 3 hours --> current =1.6*I
3 hours to 4 hours --> current =0.6*I etc.
I have tried to use the piecewise-function, but i don`t undertand how to implement it to the simulations. I have also tried the parametric sweep, but it made no sense. Obviously, I would like to plot the temperature as a function of time, and the current as a function of time, and finally compare them.
How can I solve this?
Best Regards,
Tord
2 Replies Last Post Oct 28, 2015, 5:06 a.m. EDT
Please login with a confirmed email address before reporting spam
Posted:
9 years ago
Attached my suggestion.
BR
Lasse
BR
Lasse
Attachments:
Please login with a confirmed email address before reporting spam
Posted:
9 years ago
I don`t know how to repay you Mr. Murtomäki, but thank you so much. You saved me from a lot of frustration! The model worked exactly the way I hoped. Again, thank you!
Best regards,
Tord
Best regards,
Tord