[Getdp] Complex -> time step coupling : cannot access to real part of field (bug ?)

[Gilles Vogt]

I did not find a clear solution, but using GmshRead is a good workaround
for this problem. I solve the magnetic problem, post-process it, then load
the ohmic losses map as volumetric power in the dynamic thermal simulation.

However, the issue is not solved per se : I think it might be an issue for
real magneto-thermal problems (where the permeability is a function of
temperature).

Best regards,

--
Gilles VOGT
Ingénieur généraliste de l'École Centrale de Lille, docteur en génie
électrique
+33 (0)6 25 98 72 02

2015-03-20 11:53 GMT+01:00 Gilles Vogt <vogtgilles at gmail.com>:

> Hi,
>
> I am still working on induction heating 2D coupled problems. My input file
> is written at the end of this email. As you can see, I solve in complex
> values the magnetic problem, and use the power from induced currents as
> heating power.
> The power is calculated from this code :
> -sigma[]*((Re[{ur}]-Im[w*{a}])*(Re[{ur}]-Im[w*{a}]) +
> (Im[{ur}]+Re[w*{a}])*(Im[{ur}]+Re[w*{a}]))
> Where ur is the scalar electric potential, w=2*pi*f, a the magnetic vector
> potential.
> It outputs the correct value when post-processed inside a "NameOfFormulation
> Magnetodynamics_av_2D" section. However, when post-processed inside a "NameOfFormulation
> Thermics" section, it outputs only the power from imaginary currents.
>
> A full model is attached to this email. You can check that :
> therm_OhmicL and therm_OhmicL2 give the same results
> therm_qv gives different results (the formula is the same as therm_OhmicL2
> but within the coupled problem).
>
> I have been able to confirm that this problem also occurs while solving
> the problem (the input power is only relative to the imaginary part of
> currents), and not only in post-pro.
>
> My guess is : in the time-step model, real and imaginary part of the
> complex fields are seen as t0 and t1 steps, and only t1 is considered.
>
> I hope someone can confirm the issue, or give me a workaround.
>
> Best regards,
>
>
> Here is my .pro file :
> Formulation {
>   { Name Magnetodynamics_av_2D; Type FemEquation;
>     Quantity {
>       { Name a ; Type Local ; NameOfSpace Hcurl_a_Mag_2D; }
>       { Name ur; Type Local ; NameOfSpace Hregion_u_Mag_2D; }
>       { Name I ; Type Global; NameOfSpace Hregion_u_Mag_2D [I]; }
>       { Name U ; Type Global; NameOfSpace Hregion_u_Mag_2D [U]; }
>       { Name js; Type Local ; NameOfSpace Hregion_j_Mag_2D; }
>     }
>     Equation {
>       Galerkin { [ nu[{d a}] * Dof{d a} , {d a} ]; In Domain_Mag;
>                  Jacobian Vol; Integration CurlCurl; }
>
>       Galerkin { JacNL [ dhdb_NL[{d a}] * Dof{d a} , {d a} ] ;
>                 In DomainNL ; Jacobian Vol ; Integration I1 ; }
>
>       Galerkin { DtDof [ sigma[] * Dof{a} , {a} ]; In DomainC_Mag;
>                  Jacobian Vol; Integration CurlCurl; }
>
>       Galerkin { [ sigma[] * Dof{ur} , {a} ]; In DomainC_Mag;
>                  Jacobian Vol; Integration CurlCurl; }
>
>       Galerkin { [ - Dof{js} , {a} ]; In DomainS_Mag;
>                  Jacobian Vol;
>                  Integration CurlCurl; }
>
>       Galerkin { DtDof [ sigma[] * Dof{a} , {ur} ]; In DomainC_Mag;
>                  Jacobian Vol; Integration CurlCurl; }
>       Galerkin { [ sigma[] * Dof{ur} , {ur} ]; In DomainC_Mag;
>                  Jacobian Vol; Integration CurlCurl; }
>       // GlobalTerm { [ Dof{I} , {U} ]; In DomainC_Mag; }
>     }
>   }
>
>
>   { Name TheDyn; Type FemEquation;
>     Quantity {
>       { Name t; Type Local; NameOfSpace Hgrad_T; }
>       { Name a ; Type Local ; NameOfSpace Hcurl_a_Mag_2D; }
>       { Name ur; Type Local ; NameOfSpace Hregion_u_Mag_2D; }
>     }
>     Equation {
>       Galerkin { [ lambda[] * Dof{d t} , {d t} ]; In Omega_c; Integration
> CurlCurl; Jacobian Vol;  }
>
>       Galerkin { DtDof [ rho[]*c[] * Dof{t} , {t} ]; In Omega_c;
> Integration CurlCurl; Jacobian Vol;  }
>
>       Galerkin { [ -sigma[]*((Re[{ur}]-Im[w*{a}])*(Re[{ur}]-Im[w*{a}]) +
> (Im[{ur}]+Re[w*{a}])*(Im[{ur}]+Re[w*{a}]))  , {t} ];
>       In Omega_c2; Integration CurlCurl; Jacobian Vol;  }
>
>       Galerkin { [ -qVol[]  , {t} ];
>       In DomainS_Mag; Integration CurlCurl; Jacobian Vol;  }
>
>       Galerkin { [ hS[]*Dof{t} , {t} ] ;In BdExt; Jacobian Sur ;
> Integration CurlCurl ; }
>
>       Galerkin { [ -hS[]*AmbT[] , {t} ] ; In BdExt ; Jacobian Sur ;
> Integration CurlCurl ; }
>     }
>   }
> }
>
> Resolution {
>   { Name TheDyn;
>     System {
>       { Name T; NameOfFormulation TheDyn; }
>       { Name B; NameOfFormulation Magnetodynamics_av_2D;
>          Type ComplexValue; Frequency Freq;}
>     }
>     Operation {
>       InitSolution[B];
>       IterativeLoop[Nb_max_iter, stop_criterion,
> relaxation_factor]{GenerateJac[B] ; SolveJac[B] ;}
>       SaveSolution[B];
>       InitSolution[T]; SaveSolution[T];
>       TimeLoopTheta[time0t, time1t, dtimet, theta] {
>     Generate[T]; Solve[T];
>     SaveSolution[T];
>     }
>     }
>     }
>
> }
>
> --
> Gilles VOGT
>
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