all solution of the Lorenz equation enter an ellipsoid
If σ,τ,β>0 then all solutions of the Lorenz equation
˙x | = | σ(y-x) | ||
˙y | = | x(τ-z)-y | ||
˙z | = | xy-βz |
will enter an ellipsoid centered at (0,0,2τ) in finite time.
In addition the solution will remain inside the ellipsoid once it
has entered. To observe this we define a Lyapunov function
V(x,y,z)=τx2+σy2+σ(z-2τ)2. |
It then follows that
˙V | = | 2τx˙x+2σy˙y+2σ(z-2τ)˙z | ||
= | 2τxσ(y-x)+2σy(x(τ-z)-y)+2σ(z-2τ)(xy-βz) | |||
= | -2σ(τx2+y2+β(z-r)2-bτ2). |
We then choose an ellipsoid which all the solutions will enter and remain inside. This is done by choosing a constant C>0 such that the ellipsoid
τx2+y2+β(z-r)2=bτ2 |
is strictly contained in the ellipsoid
τx2+σy2+σ(z-2τ)2=C. |
Therefore all solution will eventually enter and remain inside the above ellipsoid since ˙V<0 when a solution is located at the exterior of the ellipsoid.
Title | all solution of the Lorenz equation enter an ellipsoid |
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Canonical name | AllSolutionOfTheLorenzEquationEnterAnEllipsoid |
Date of creation | 2013-03-22 15:15:28 |
Last modified on | 2013-03-22 15:15:28 |
Owner | Daume (40) |
Last modified by | Daume (40) |
Numerical id | 4 |
Author | Daume (40) |
Entry type | Result |
Classification | msc 34-00 |
Classification | msc 65P20 |
Classification | msc 65P30 |
Classification | msc 65P40 |
Classification | msc 65P99 |