Schmucker-Weidelt Lecture Notes, Aarhus, 1975 - MTNet

Schmucker-Weidelt Lecture Notes, Aarhus, 1975 - MTNet Schmucker-Weidelt Lecture Notes, Aarhus, 1975 - MTNet

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The iteration is carried out either alonq rows or colums. Generally the GauO-Seidel iteration procedure is used with a successive over- relaxation factor to speed up convergence.. 3.3. P.nomalous slab as basic domain In practice it is not necessary to solve the diffusion equation by finite differences in t.he total conductor and the air half-space. Instead it is sufficient to treat the equation only in that slab which contains the anomalous domain. Let the anomalous slab be confined to the depth range zl 5 z 5 z2. Within this domain we have to solve the inho3nogeneous equation (considering for the moment only the TE-case) subject to two homogeneous boundary conditiolls at z = z and z2, 1 ~Thich involve a for z < z and z > z2 respectively and account for n 1 the vanishing anomalous field for z -t 2 m. Yihen (3.25) is solved by finite differences, the discretization invol.ves also the field values one grid point width above and below the anomalous slab. The idea is to express these values in terms of a line integral over Ea at z = z and z2 respectively. I Let V and V2 be the half-planes z - < zl and z -- > z2, respectively. ~ e G t r [r). 2, r, be Green's functions which satisfy " "m (-0 - subject to the boundary condition In V and V2, E is a solution of 1 a Now Green's formula for two-dimensions states that

The RHS i.s a closed line integral bordering the area over which the LIIS integral is performed. I11 the RHS differentiation in direction to the outr,?ard normal is involved. From (3.28) and (3.26) fol.lows Identi.fying U with GI V with Ea, Eq. (3.29) yields in virtue of (3.27) E - a Q around Vm I r - a an G ( ~ (&IL)ds. ) Now G'") and its normal derivative vanish at infinity. Hence, only the part of the line integral along the axis z = z contrihut-.es. a a m Por m=? : - a - - m=2 : - a =-- 2n az' an az' Hence, Because of (3.26) , Eq. (3.30) depends only on the difference y-yo. Defining q . (3.30) reads shorter For a layered structure in Vm, the kernels R (m)' are easily deter- mined:

The RHS i.s a closed line integral bordering the area over which the<br />

LIIS integral is performed. I11 the RHS differentiation in direction<br />

to the outr,?ard normal is involved.<br />

From (3.28) and (3.26) fol.lows<br />

Identi.fying U with GI V with Ea, Eq. (3.29) yields in virtue of<br />

(3.27)<br />

E -<br />

a Q<br />

around Vm<br />

I<br />

r - a an G ( ~ (&IL)ds.<br />

)<br />

Now G'") and its normal derivative vanish at infinity. Hence, only<br />

the part of the line integral along the axis z = z contrihut-.es.<br />

a a m<br />

Por m=? : - a - - m=2 : - a =--<br />

2n az' an az'<br />

Hence,<br />

Because of (3.26) , Eq. (3.30) depends only on the difference y-yo.<br />

Defining<br />

q . (3.30) reads shorter<br />

For a layered structure in Vm, the kernels R (m)' are easily deter-<br />

mined:

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