Discussion Forum

Hello,

Although I have some experience with FEM, I am a new user of Comsol. I am trying to solve a simple problem in 3D: a square section solenoid with an iron core. After the definition of the materials and current at the winding block, I tried to compute the study, but I got the following message of errors:

" Attempt to evaluate negative power of zero.
- Function: ^
Failed to evaluate temporary symbolic derivative variable.
- Variable: mod1.mf.murzz@VDN$mod1.curlAz
- Defined as: (dmod1.mat2.def.MUR_dx1((sqrt(((mod1.mf.Bz^2)+((mod1.mf.By^2)+(mod1.mf.Bx^2))))/unit_T_cf))*((1/unit_T_cf)*((2*mod1.mf.Bz)*((((mod1.mf.Bz^2)+((mod1.mf.By^2)+(mod1.mf.Bx^2)))^-0.5)*0.5))))
Failed to evaluate temporary symbolic derivative variable.
- Variable: mod1.mf.murinvzz@VDN$mod1.curlAz
- Defined as: (((dmod1.mat2.def.MUR_dx1((sqrt(((mod1.mf.Bz^2)+((mod1.mf.By^2)+(mod1.mf.Bx^2))))/unit_T_cf))*((1/unit_T_cf)*((2*mod1.mf.Bz)*((((mod1.mf.Bz^2)+((mod1.mf.By^2)+(mod1.mf.Bx^2)))^-0.5)*0.5)))))*((-1)/(mod1.mf.murzz^2)))
Failed to evaluate temporary symbolic derivative variable.
- Variable: mod1.mf.Hz@VDN$mod1.curlAz
- Defined as: ((1/mu0_const)*(mod1.mf.murinvzz+(mod1.mf.Bz*((((dmod1.mat2.def.MUR_dx1((sqrt(((mod1.mf.Bz^2)+((mod1.mf.By^2)+(mod1.mf.Bx^2))))/unit_T_cf))*((1/unit_T_cf)*((2*mod1.mf.Bz)*((((mod1.mf.Bz^2)+((mod1.mf.By^2)+(mod1.mf.Bx^2)))^-0.5)*0.5)))))*((-1)/(mod1.mf.murzz^2)))))))
Failed to evaluate expression.
- Expression: d(d((-mod1.mf.Hx*test(mod1.curlAx)-mod1.mf.Hy*test(mod1.curlAy)-mod1.mf.Hz*test(mod1.curlAz)+mod1.mf.Jx*test(mod1.Ax)+mod1.mf.Jy*test(mod1.Ay)+mod1.mf.Jz*test(mod1.Az))*(dvol),{test@3}),mod1.curlAz)"

However, when I just modify the material of the core to another kind (air, for example), the study is computed without problems.


Could somebody help me in this problem?

Thanks in advance.