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Error Sol1/S1
Posted Feb 2, 2012, 7:51 p.m. EST Version 4.0a 2 Replies
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Hello,
First of all I would like to say I am a first time user of Comsol so please bear with me.
The error expression that I get in comsol is:
Attempt to evaluate negative power of zero.
- Function: ^
Failed to evaluate expression.
- Expression: d(d((-5.3079*(0.6+3523.3558082974137*(-294.15+mod1.T)^(1/6))^2*(293.15*unit_K_cf-mod1.T)*test(mod1.T))*(dvol),{test@0}),mod1.T)
First of all I would like to say I am a first time user of Comsol so please bear with me.
The error expression that I get in comsol is:
Attempt to evaluate negative power of zero.
- Function: ^
Failed to evaluate expression.
- Expression: d(d((-5.3079*(0.6+3523.3558082974137*(-294.15+mod1.T)^(1/6))^2*(293.15*unit_K_cf-mod1.T)*test(mod1.T))*(dvol),{test@0}),mod1.T)
2 Replies Last Post Feb 3, 2012, 1:13 a.m. EST
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Posted:
1 decade ago
Hi
it looks like you are getting negative Temperatures, this can happen in time stepping if you have not adjusted time steps and mesh size w.r.t. material alpha = k/rho/Cp
Another case could be a unit confusion °C and K
If you upgrade to latest version the solvers seem to be better prepared to handle these cases, but check carefully the alpha versus Dt step and "h" mesh size in region with high temperature gradients, these are the minimum rules you should check otherwise FEM method cannot work, and that is not a COMSOl issue but a math and sampling theory issue ;)
But it might be something else too ;)
--
Good luck
Ivar
it looks like you are getting negative Temperatures, this can happen in time stepping if you have not adjusted time steps and mesh size w.r.t. material alpha = k/rho/Cp
Another case could be a unit confusion °C and K
If you upgrade to latest version the solvers seem to be better prepared to handle these cases, but check carefully the alpha versus Dt step and "h" mesh size in region with high temperature gradients, these are the minimum rules you should check otherwise FEM method cannot work, and that is not a COMSOl issue but a math and sampling theory issue ;)
But it might be something else too ;)
--
Good luck
Ivar
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Posted:
1 decade ago
Hi MARK,
I understand your problems ..
most of the errors in comsol are hard to understand ..
the easiest way to identify problems is by carefully following it. (actually its nt easy way .. )
first see the domain , or bounday or the edge where that problem was felt ...
in your case its a function !
so trouble shoot the syntax of the function.
and you can attach the file for better support from friends !!
I understand your problems ..
most of the errors in comsol are hard to understand ..
the easiest way to identify problems is by carefully following it. (actually its nt easy way .. )
first see the domain , or bounday or the edge where that problem was felt ...
in your case its a function !
so trouble shoot the syntax of the function.
and you can attach the file for better support from friends !!