Jeff Hiller
COMSOL Employee
Please login with a confirmed email address before reporting spam
Posted:
9 years ago
Mar 9, 2016, 9:44 a.m. EST
Yes, just use a rectangular function to define your heat source: Definitions>Functions>Rectangle.
Best,
Jeff
Edit: I am not sure if that feature already existed in version 4.3. If not, you can get something similar by taking the product of two smoothed Heaviside step functions, etc.
Yes, just use a rectangular function to define your heat source: Definitions>Functions>Rectangle.
Best,
Jeff
Edit: I am not sure if that feature already existed in version 4.3. If not, you can get something similar by taking the product of two smoothed Heaviside step functions, etc.
Please login with a confirmed email address before reporting spam
Posted:
9 years ago
Mar 9, 2016, 9:48 a.m. EST
Hey Jeff,
But how do I make it start when the temperature reaches the desired value? I can definitely define a rectangular step function as a function of time. But I need the temperature condition.
Paul
Hey Jeff,
But how do I make it start when the temperature reaches the desired value? I can definitely define a rectangular step function as a function of time. But I need the temperature condition.
Paul
Jeff Hiller
COMSOL Employee
Please login with a confirmed email address before reporting spam
Posted:
9 years ago
Mar 9, 2016, 9:50 a.m. EST
I had not realized you did not know in advance how long your up time needs to be.
Instead you can use the concept of Events. See this link:
www.comsol.com/blogs/implementing-a-thermostat-with-the-events-interface/
Best,
Jeff
I had not realized you did not know in advance how long your up time needs to be.
Instead you can use the concept of Events. See this link: http://www.comsol.com/blogs/implementing-a-thermostat-with-the-events-interface/
Best,
Jeff
Please login with a confirmed email address before reporting spam
Posted:
9 years ago
Mar 9, 2016, 9:56 a.m. EST
Hey Jeff,
Thanks for the help. I was thinking about events. But an event would give me a temperature dependence and that's all. I can have for example an event that has 0 until the temperature is reached. Then 1 when the temperature is reached. How do I make it back to 0 after a certain time?
Is it me, or I didn't see this information in the thread you have just provided (I know it from before)? And can I also implement time conditions in the events?
Paul
Hey Jeff,
Thanks for the help. I was thinking about events. But an event would give me a temperature dependence and that's all. I can have for example an event that has 0 until the temperature is reached. Then 1 when the temperature is reached. How do I make it back to 0 after a certain time?
Is it me, or I didn't see this information in the thread you have just provided (I know it from before)? And can I also implement time conditions in the events?
Paul
Walter Frei
COMSOL Employee
Please login with a confirmed email address before reporting spam
Posted:
9 years ago
Mar 9, 2016, 10:59 a.m. EST
Dear Paul,
You can indeed expand upon the approach outlined here:
www.comsol.com/blogs/implementing-a-thermostat-with-the-events-interface/
and modify as demonstrated in the attached file.
Note these features:
- An additional ODE for a variable "HeaterOnTime" that simply integrates "1" over time, thereby keeping track of time since any event at which HeaterOnTime is set to zero.
- An indicator state variable called "On_Time" that goes from negative to positive after a specified time.
- Implicit Event 1, that triggers when the temperature gets too low, and sets HeaterOnTime = 0
- Implicit event 2, that triggers based in the On_Time > 0 which turns off the heater.
Hopefully this is all fairly self-explanatory from here on. Please note that this file is created in version 5.2.
Best Regards,
Dear Paul,
You can indeed expand upon the approach outlined here:
http://www.comsol.com/blogs/implementing-a-thermostat-with-the-events-interface/
and modify as demonstrated in the attached file.
Note these features:
- An additional ODE for a variable "HeaterOnTime" that simply integrates "1" over time, thereby keeping track of time since any event at which HeaterOnTime is set to zero.
- An indicator state variable called "On_Time" that goes from negative to positive after a specified time.
- Implicit Event 1, that triggers when the temperature gets too low, and sets HeaterOnTime = 0
- Implicit event 2, that triggers based in the On_Time > 0 which turns off the heater.
Hopefully this is all fairly self-explanatory from here on. Please note that this file is created in version 5.2.
Best Regards,
Please login with a confirmed email address before reporting spam
Posted:
9 years ago
Mar 9, 2016, 4:00 p.m. EST
Dear Walter,
Thank you very much! I don't have 5.2, but I will install it for this and I will write back if I encounter any problems.
Best Regards,
Paul
Dear Walter,
Thank you very much! I don't have 5.2, but I will install it for this and I will write back if I encounter any problems.
Best Regards,
Paul
Please login with a confirmed email address before reporting spam
Posted:
9 years ago
Mar 10, 2016, 7:58 a.m. EST
Dear Walter,
Thank you very much. It works as it should.
Paul
Dear Walter,
Thank you very much. It works as it should.
Paul