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How to control temperature ramp up/down time?

Posted 1 set 2011, 17:51 GMT-4 Heat Transfer & Phase Change, Modeling Tools & Definitions, Parameters, Variables, & Functions, Structural Mechanics Version 4.2 2 Replies

Wenjun Jiang
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Hello,

I'm new in COMSOL. Currently I'm trying to simulate the stress on SiO2 thin film on silicon wafer based on the temperature ramp up/down from furnace.

I'm currently using time-dependent Heat Transfer module together with Structural Mechanics module to conduct the simulation, but I'm unable to find any place where I can specify the starting / ending temperature as well as the linear temperature ramp time. Can I set a parameter such as $time for time-dependence?

Can anyone give me some suggestion?

Thanks,

Albert
2 Replies Last Post 2 set 2011, 15:38 GMT-4
Edgar Kaiser
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Posted: 1 decade ago 2 set 2011, 03:39 GMT-4
Hi,

you can use COMSIOLs time variable 't' to define a time-dependent expression for the heated (cooled) boundaries or domains.

Cheers
Edgar
Hi, you can use COMSIOLs time variable 't' to define a time-dependent expression for the heated (cooled) boundaries or domains. Cheers Edgar
Wenjun Jiang
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Posted: 1 decade ago 2 set 2011, 15:38 GMT-4
Thanks. Here is the problem:

boundary 1: symmetry
--------------------------------------------------
boundary 2: boundary not set |
---------------------- furnace with air |
Silicon wafer | boundary 3||||||| boundary 6
---------------------- furnace with air |
boundary 4: boundary not set |
--------------------------------------------------
boundary 5: symmetry

Boundaries 2-4 form the silicon wafer region, while boundaries 1,5,6 form the surrounding furnace region containing air. I want the boundaries 6 to linearly ramp the temperature from T_start to T_end.

Now I'm using Heat Transfer module, with Initial Values1 of both domains (silicon and air) set to be T_start. Then I choose Temperature1 to boundary6, with ramping temperature T0=T_start+ramp_rate*t. Also I set Symmetry1 to boundaries 1&5.

However, I don't know how to set the Surface-to-Surface Radiation part. I chose boundaries 3&6 together, with Radiation direction to be Opacity controlled, Ambient temperature to be T_start, Surface emissivity to be 0.1, and Initial Values of Surface radiosity to be J=0 W/m^2. But when I ran the time dependent study, with Times to be set as "range(0, 1[min], (T_end-T_start)/ramp_rate", I got an error: "Radiation error: exactly one adjacent domain must be opaque. By default all the domains are transparent. Consider right-clicking the node where temperature is defined to add the Opaque subfeature."

By contrast, if I changed the Radiation direction to be either "Positive normal direction" or "Negative normal direction", with Ambient temperature to be Tamb=T_start + ramp_rate*t, I didn't get the error, but the 3D temperature plot showed no temperature at all: the final temperature is T_start everywhere !

Can anyone have any suggestion where is the error (I understand that I need to set up the opaque boundary condition, but I don't know how to set it up...), and how should I ramp up the temperature?

Thanks,

Albert
Thanks. Here is the problem: boundary 1: symmetry -------------------------------------------------- boundary 2: boundary not set | ---------------------- furnace with air | Silicon wafer | boundary 3||||||| boundary 6 ---------------------- furnace with air | boundary 4: boundary not set | -------------------------------------------------- boundary 5: symmetry Boundaries 2-4 form the silicon wafer region, while boundaries 1,5,6 form the surrounding furnace region containing air. I want the boundaries 6 to linearly ramp the temperature from T_start to T_end. Now I'm using Heat Transfer module, with Initial Values1 of both domains (silicon and air) set to be T_start. Then I choose Temperature1 to boundary6, with ramping temperature T0=T_start+ramp_rate*t. Also I set Symmetry1 to boundaries 1&5. However, I don't know how to set the Surface-to-Surface Radiation part. I chose boundaries 3&6 together, with Radiation direction to be Opacity controlled, Ambient temperature to be T_start, Surface emissivity to be 0.1, and Initial Values of Surface radiosity to be J=0 W/m^2. But when I ran the time dependent study, with Times to be set as "range(0, 1[min], (T_end-T_start)/ramp_rate", I got an error: "Radiation error: exactly one adjacent domain must be opaque. By default all the domains are transparent. Consider right-clicking the node where temperature is defined to add the Opaque subfeature." By contrast, if I changed the Radiation direction to be either "Positive normal direction" or "Negative normal direction", with Ambient temperature to be Tamb=T_start + ramp_rate*t, I didn't get the error, but the 3D temperature plot showed no temperature at all: the final temperature is T_start everywhere ! Can anyone have any suggestion where is the error (I understand that I need to set up the opaque boundary condition, but I don't know how to set it up...), and how should I ramp up the temperature? Thanks, Albert

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