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step function

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Hi,

I am trying to simulate heat transfer problem. I have the values of voltage V_in and Watt density Q_in of the heat source and the heat source is attached under a lid. Now, I want to assign a step function such that when I apply current to the heater, it gets heated to certain temperature Tmax and at this particular time I would like to turn/switch off the current supply, so that the heater temperature goes down eventually. I just want to check the temperature distributionon over the lid to which the heater is attached.

Please let me know how to go about it.
Thanks in advance!!

4 Replies Last Post Apr 14, 2014, 4:35 p.m. EDT
Sergei Yushanov Certified Consultant

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Posted: 1 decade ago Mar 31, 2014, 7:45 a.m. EDT
Karan,

Under Definitions/Component Coupling/Maximum, define operator “maxop1” on the domain Geometric level. Then use expression

Q_in*(maxop1(T)<=Tmax)

to turn-off heat source when temperature exceeds the specified value “Tmax”.

Regards,
Sergei
Karan, Under Definitions/Component Coupling/Maximum, define operator “maxop1” on the domain Geometric level. Then use expression Q_in*(maxop1(T)

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Posted: 1 decade ago Mar 31, 2014, 6:31 p.m. EDT
Mr. Yushanov

Thank you for the reply.
I used the expression you had suggested and I wasnt successful in getting any result. Meaning there wasnt any temperature change.

The procedure I followed is;
As suggested;
Under Definitions/Component Coupling/Maximum, define operator “maxop1” on the domain Geometric level--selected the heater domain only..

and also,
In Model--definitions--variables1--
Assigned variable, Q_in as Q_in*(maxop1(T)<=Tmax)

Further Will I have to include the Input voltage also with the same expression.?

Regards,
Karan




Mr. Yushanov Thank you for the reply. I used the expression you had suggested and I wasnt successful in getting any result. Meaning there wasnt any temperature change. The procedure I followed is; As suggested; Under Definitions/Component Coupling/Maximum, define operator “maxop1” on the domain Geometric level--selected the heater domain only.. and also, In Model--definitions--variables1-- Assigned variable, Q_in as Q_in*(maxop1(T)

Sergei Yushanov Certified Consultant

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Posted: 1 decade ago Apr 1, 2014, 7:29 a.m. EDT
Karan,

To turn-off voltage source write input electrical potential as V_in*(maxop1(T)<=Tmax).

Regards,
Sergei
Karan, To turn-off voltage source write input electrical potential as V_in*(maxop1(T)

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Posted: 1 decade ago Apr 14, 2014, 4:35 p.m. EDT
Hello,

The maxop input assigned performs the required function. But, immediately after reaching the maximum value the solution blows up with an error-(May have reached a singularity)..I would like to see the temperature dropping down after reaching Tmax..

Please let me know.
Hello, The maxop input assigned performs the required function. But, immediately after reaching the maximum value the solution blows up with an error-(May have reached a singularity)..I would like to see the temperature dropping down after reaching Tmax.. Please let me know.

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