3d_capacitor

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3d_capacitor

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{  3D_CAPACITOR.PDE  

 

 This problem is an extension of "3D_EXTRUSION_SPEC.PDE", and shows

 a capacitor formed by two metal strips of different size separated

 by a sheet of dielectric.

 

}  

 

TITLE '3D Capacitor'  

 

COORDINATES  

 CARTESIAN3  

 

SELECT  

 { rename the axes }

alias(x) = "X(mm)"      

alias(y) = "Y(mm)"  

alias(z) = "Z(mm)"  

 { paint all contours }

 PAINTED                

 

VARIABLES  

 V  

 

DEFINITIONS  

 Kdiel= 6  

 Kmetal=1e6  

 Kair=1  

 K = Kair { default K to Kair - this will change in some layers/regions }  

 V0 = 0  

 V1 = 1  

 Eps0 = 8.854e-12                     { Farads/M }  

 Eps0mm = 0.001*Eps0                   { Farads/mm }  

 W = integral(0.5*K*eps0mm*grad(V)^2) { Stored Energy }  

 C = 1.0e6*2*W/(V1-V0)^2               { Capacitance in microFarads }  

 

EQUATIONS  

 V : DIV(K*GRAD(V)) = 0  

 

EXTRUSION  

SURFACE   "Bottom"                    Z=0  

  LAYER   "Bottom Air"  

SURFACE   "Bottom Air - Metal"        Z=0.9  

  LAYER   "Bottom Metal"  

SURFACE   "Bottom Metal - Dielectric" Z=1  

  LAYER   "Dielectric"  

SURFACE   "Top Metal - Dielectric"    Z=2  

  LAYER   "Top Metal"  

SURFACE   "Top Metal - Air"           Z=2.1  

  LAYER   "Top Air"  

SURFACE   "Top"                       Z=3  

 

BOUNDARIES  

SURFACE "Bottom" NATURAL(V)=0 { Insulators top and bottom }  

SURFACE "Top"   NATURAL(V)=0  

 

REGION 1 { this is the outer boundary of the system }  

    LAYER "dielectric" K = Kdiel { all other layers default to Kair }  

    START(0,0)  

    LINE TO (5,0) TO (5,5) TO(0,5) to close  

 

  LIMITED REGION 2 { the larger bottom plate }  

    SURFACE "Bottom Air - Metal"       VALUE(V)=V0
    SURFACE "Bottom Metal - Dielectric" VALUE(V)=V0
    LAYER "Bottom Metal" K = Kmetal  

    START(1,0)  

    LAYER "Bottom Metal" VALUE(V)=V0  

    LINE TO (4,0)  

    LAYER "Bottom Metal" NATURAL(V)=0  

    Line TO (4,4) TO (1,4) to close  

 

  LIMITED REGION 3 { the smaller top plate}  

    SURFACE "Top Metal - Dielectric" VALUE(V)=V1
    SURFACE "Top Metal - Air"       VALUE(V)=V1
    LAYER "Top Metal" K = Kmetal  

    START(2,1)  

    LINE TO (3,1) TO (3,5)  

    LAYER "Top Metal" VALUE(V)=V1  

    LINE TO (2,5)  

    LAYER "Top Metal" NATURAL(V)=0  

    LINE to close  

 

MONITORS  

CONTOUR(V) ON Y=2.5  

 

PLOTS  

GRID(X,Z) ON Y=2.5  

CONTOUR(V) ON X=2.5 REPORT(C) as "Capacitance(uF)"  

CONTOUR(V) ON Y=2.5 REPORT(C) as "Capacitance(uF)"  

CONTOUR(V) ON Z=1.5 REPORT(C) as "Capacitance(uF)"  

CONTOUR(1/K) ON Y=2.5 as "Material"  

 

END