Hey,
I’m fairly new to COMSOL and trying to use the Electric Currents and Heat Transfer Interface to simulate the heating process caused by an applied voltage in a solid.
If I implement the applied Voltage using the piecewise function the simulation works just fine, but if I try to implement the signal using a rectangular function and making it periodic by using the analytic function (like I read it in a few other discussions), the simulation works a lot worse (meaning: it takes much longer to solve, the time steps need to be a lot smaller (0.01 -> 0.005) and the convergence plots don’t look very good).
I want to be able to change the signal (“on”-time, “off”-time, amplitude, and the overall pulse train time) without having to change all the values in the piecewise function. I would really appreciate it if anyone could tell me what the difference is between the piecewise and analytic function since I seem to be missing something here. Like I said it is not working properly with the analytic function and to me they look exactly the same.
This is what I have done so far:
The applied Voltage is a periodic rectangular function for about 15 seconds (the last pulse should finish regularly before the signal stops), after that it is zero before the simulations stops (to look at the cooling due to convection).
The amplitude is 50 V, the pulse is turned “on” for 500 ms and turned “off” for 150 ms.
Version 1 (works perfectly)
Piecewise function (pw1):
-> see pw1.jpg
I implement the signal with the terminal at the electric currents interface (terminal type: voltage): 50*pw1(t[1/s])
I use a userdefined mesh and the time dependent study.
Version 2 (doesn't rally work) - I use the rectangle and analytic function to implement the pulse:
Global Parameters:
rt: rise time = 25 ms
ampl: amplitude of the signal = 50
p: period = 650 ms
V_an: time for how long the pulse sequence should be turned on = 15 s
rectangle (rect3):
-> see rect3.jpg
analytic (an5):
-> see an5.jpg
analytic (an6):
-> see an6.jpg
I implement the signal with the terminal: an6(t[1/s])
I use a userdefined mesh and the time dependent study. Also I changed the time stepping in the time-dependent solver intermediate.
Thanks a lot for your help!
Yasmin
I’m fairly new to COMSOL and trying to use the Electric Currents and Heat Transfer Interface to simulate the heating process caused by an applied voltage in a solid.
If I implement the applied Voltage using the piecewise function the simulation works just fine, but if I try to implement the signal using a rectangular function and making it periodic by using the analytic function (like I read it in a few other discussions), the simulation works a lot worse (meaning: it takes much longer to solve, the time steps need to be a lot smaller (0.01 -> 0.005) and the convergence plots don’t look very good).
I want to be able to change the signal (“on”-time, “off”-time, amplitude, and the overall pulse train time) without having to change all the values in the piecewise function. I would really appreciate it if anyone could tell me what the difference is between the piecewise and analytic function since I seem to be missing something here. Like I said it is not working properly with the analytic function and to me they look exactly the same.
This is what I have done so far:
The applied Voltage is a periodic rectangular function for about 15 seconds (the last pulse should finish regularly before the signal stops), after that it is zero before the simulations stops (to look at the cooling due to convection).
The amplitude is 50 V, the pulse is turned “on” for 500 ms and turned “off” for 150 ms.
Version 1 (works perfectly)
Piecewise function (pw1):
-> see pw1.jpg
I implement the signal with the terminal at the electric currents interface (terminal type: voltage): 50*pw1(t[1/s])
I use a userdefined mesh and the time dependent study.
Version 2 (doesn't rally work) - I use the rectangle and analytic function to implement the pulse:
Global Parameters:
rt: rise time = 25 ms
ampl: amplitude of the signal = 50
p: period = 650 ms
V_an: time for how long the pulse sequence should be turned on = 15 s
rectangle (rect3):
-> see rect3.jpg
analytic (an5):
-> see an5.jpg
analytic (an6):
-> see an6.jpg
I implement the signal with the terminal: an6(t[1/s])
I use a userdefined mesh and the time dependent study. Also I changed the time stepping in the time-dependent solver intermediate.
Thanks a lot for your help!
Yasmin