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.
1D heat model question, time dependent
Posted Jun 4, 2017, 10:13 p.m. EDT 1 Reply
Please login with a confirmed email address before reporting spam
Hi, I'm trying to model heat loss between different material. I can find the heat flux at the given point given the time, however when i integrate the heat flux with respect to time to figure out how much heat is lost at a given area [J/m^2] I get a large negative number after 0.1 second. The point that this happens is where 2 materials touch (I'm assuming that they're touching perfectly right now). I've noticed that the point becomes near the average of the temperature of the two materials, however I want to assume that the temperature at this point is the same as the first material and that any equation to smooth out the transition between materials occurs in the second material so that there is heat loss at this point. I've tried setting the temperature of the point to the static state temperature, however that is not good enough.
Thanks
Thanks
1 Reply Last Post Jun 5, 2017, 11:46 p.m. EDT
Please login with a confirmed email address before reporting spam
Posted:
7 years ago
Updated:
7 years ago
Mike,
I worked on a similar problem (liquid in contact with vapor) and would like to share my experience.
1) I used one heat transfer physics for each domain (ht, ht2). Therefore, I had two variables, T in domain 1 and T2 in domain 2. You may link the temperatures at the boundary like: T=T2+0.2.
2) Try to read more about the "up" and "down" operators in the documentation. Each represents one side of the interface. Sometimes, up(variable) and down(variable) are not equal.
3) Use contact pair and continuity of heat flux at the boundary. For this, you need to form the geometry as "assembly" not "'union".
4) Finally, a negative number for heat flux may be correct. It might have shown that the heat is flowing in an opposite direction to the axis.
Hope my instructions help you. If you don't get the desired results, then someone else may guide you here or ask comsol support team directly.
Amin,
I worked on a similar problem (liquid in contact with vapor) and would like to share my experience.
1) I used one heat transfer physics for each domain (ht, ht2). Therefore, I had two variables, T in domain 1 and T2 in domain 2. You may link the temperatures at the boundary like: T=T2+0.2.
2) Try to read more about the "up" and "down" operators in the documentation. Each represents one side of the interface. Sometimes, up(variable) and down(variable) are not equal.
3) Use contact pair and continuity of heat flux at the boundary. For this, you need to form the geometry as "assembly" not "'union".
4) Finally, a negative number for heat flux may be correct. It might have shown that the heat is flowing in an opposite direction to the axis.
Hope my instructions help you. If you don't get the desired results, then someone else may guide you here or ask comsol support team directly.
Amin,