Abstract
The amplitude equations that govern the motion of wavetrains near the critical point of unstable dispersive, weakly nonlinear physical systems are considered on slow time and space scales
T
m
═ ε
m
t
;
X
m
═ ε
m
x
(
m
═ 1, 2,...). Such systems arise when the dispersion relation for the harmonic wavetrain is purely real and complex conjugate roots appear when a control parameter (
μ
) is varied. At the critical point, when the critical wavevector
k
c
is non-zero, a general result for this general class of unstable systems is that the typical amplitude equations are either of the form ( ∂/∂
T
1
+
c
1
∂/∂
X
1
) (∂/∂
T
1
+
c
2
∂/∂
X
1
)
A
═ ±α
A
─ β
AB
, ( ∂/∂
T
1
+
c
2
∂/∂
X
1
)
B
═ (∂/∂
T
1
+
c
1
∂/∂
X
1
) |
A
|
2
, or of the form ( ∂/∂
T
1
+
c
1
∂/∂
X
1
) (∂/∂
T
1
+
c
2
∂/∂
X
1
)
A
═ ±α
A
- β
A
|
A
|
2
. The equations with the
AB
-nonlinearity govern for example the two-layer model for baroclinic instability and self-induced transparency (s. i. t.) in ultra-short optical pulse propagation in laser physics. The second equation occurs for the two-layer Kelvin-Helmholtz instability and a problem in the buckling of elastic shells. This second type of equation has been considered in detail by Weissman. The
AB
-equations are particularly important in that they are integrable by the inverse scattering transform and have a variety of multi-soliton solutions. They are also reducible to the sine-Gordon equation
ϕ
ξƬ
═ ± sin
ϕ
when
A
is real. We prove some general results for this type of instability and discuss briefly their applications to various other examples such as the two-stream instability. Examples in which dissipation is the dominant mechanism of the instability are also briefly considered. In contrast to the dispersive type which operates on the
T
1
-time scale, this type operates on the
T
2
-scale.
Reference40 articles.
1. Stud;Akylas T. R.;AppMath.,1980
2. The disintegration of wave trains on deep water Part 1. Theory
3. J;Charney J. G.;Met.,1947
4. The propagation of a weak nonlinear wave
5. J . R. met;Drazin P. G.;Soc.,1970
Cited by
50 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献