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Institut für Allgemeine Elektrotechnik, Uni Rostock - Universität ...

Institut für Allgemeine Elektrotechnik, Uni Rostock - Universität ...

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Central Difference Quotient (Leap Frog)<br />

⎛ 2 1 1 1<br />

Inserting the estimate ωmax<br />

≤ max = max<br />

+ +<br />

⎜<br />

⎝ ε u v w<br />

iµ<br />

Δ Δ Δ<br />

i<br />

for the absolute largest eigenvalue yields again<br />

⎧<br />

⎫<br />

1<br />

⎪<br />

⎪<br />

Δt ≤Δt max<br />

≈min ⎨ εi µ<br />

i<br />

⋅<br />

,<br />

i<br />

1 1 1<br />

⎬<br />

⎪<br />

+ + ⎪<br />

2 2 2<br />

⎪⎩<br />

Δui Δvi Δwi<br />

⎪⎭<br />

i.e. the Courant-Friedrichs-Levy condition.<br />

( ωi<br />

) ⎜<br />

2 2 2<br />

i i i<br />

⎞<br />

⎟<br />

⎠<br />

ω<br />

max<br />

can also be determined numerically, yielding an<br />

exact stability limit for the leap-frog scheme.<br />

Prof. Dr. Ursula van Rienen, <strong>Uni</strong>versität <strong>Rostock</strong>, Fakultät <strong>für</strong> Informatik und <strong>Elektrotechnik</strong> (IEF), <strong>Institut</strong> <strong>für</strong> <strong>Allgemeine</strong> <strong>Elektrotechnik</strong> (IAE)<br />

28

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