COMSOL Forums: Set sin function in my heat flux boundary condition

Re: Set sin function in my heat flux boundary condition

Sun, 11 Sep 2011 15:57:43 +0000

Thanks. It worked.

Re: Set sin function in my heat flux boundary condition

Sat, 10 Sep 2011 07:32:23 +0000

Hi

the unit mishmthc is that "t" has units [s] and the operator sin() wants unitless values:

hence you shoud either write a[m]=a0[m]*sin(2*pi*f[Hz]*t[s]) without necessarily all units if already defined
or just sin(t[1/s]) to be unitless

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Good luck
Ivar

Re: Set sin function in my heat flux boundary condition

Fri, 09 Sep 2011 18:32:29 +0000

I am trying to change the external temperature as a sinusoidal function of time. The model is in transient mode, yet i still get the unit error when i simply plug in ext. temp = 280*Sin(t).
I also tried to change it from global expression, but still i get the unit mismatch error. How else can i change the external temperature as a sine function?

Appreciate any help. Thanks

Re: Set sin function in my heat flux boundary condition

Thu, 18 Mar 2010 20:01:10 +0000

Hi

I would try to multiply the heat source value (amplitude) by a "*sin(2*pi*t)" factor.

But as "t" is only defined in "transient mode" you would get an error message if you switch to back to stationary, without supressing it again.

Good luck
Ivar

Set sin function in my heat flux boundary condition

Thu, 18 Mar 2010 17:27:31 +0000

Hello Guys,

I do not know how I can set a function in my boundary condition rather than a scalar. I need to define my wall's heat flux as a function of time which is almost like a sin function. I am sure the COMSOL should be able to handle that, but I do not know how!

Thank you

Ehsan