A new approach to the Rayleigh-Taylor instability is presented that yields exact solutions for the simplest cases and provides approximate but still very accurate analytical expressions for important and more complex cases involving nonideal fluids. The approach is based on Newton’s second law and allows for an intuitive and physically appealing explanation of the mechanisms underlying the instability.

1.
G. K.
Batchelor
,
An Introduction to Fluid Dynamics
(
Cambridge U. P.
, Cambridge,
1973
).
2.
R. A.
Racca
and
C. H.
Annett
, “
Simple demonstration of Rayleigh-Taylor instability
,”
Am. J. Phys.
53
,
484
486
(
1985
).
3.
R. F.
Benjamin
, “
Rayleigh-Taylor instability-fascinating gateway to the study of fluid dynamics
,”
Phys. Teach.
37
,
332
336
(
1999
).
4.
D. H.
Sharp
, “
An overview of Rayleigh-Taylor instability
,”
Physica D
12
,
3
18
(
1984
).
5.
Lord
Rayleigh
,
Scientific Papers
(
Cambridge, U. P.
, Cambridge,
1900
), Vol.
II
, pp.
200
207
.
6.
G. I.
Taylor
, “
The instability of liquid surfaces when accelerated in a direction perpendicular to their planes
,”
Proc. R. Soc. London, Ser. A
201
,
192
196
(
1950
).
7.
D. J.
Lewis
, “
The instability of liquid surfaces when accelerated in a direction perpendicular to their planes. II
,”
Proc. R. Soc. London, Ser. A
202
,
81
96
(
1950
).
8.
A.
Cui
and
R. L.
Street
, “
Large-eddy simulation of coastal upwelling flow
,”
Environmental Fluid Mechanics
4
,
197
223
(
2004
).
9.
V.
Bychkov
and
M. A.
Liberman
, “
Hydrodynamic instabilities of the flame front in white dwarfs
,”
Astron. Astrophys.
16
,
727
734
(
1995
).
10.
X.
Ribeyre
,
V. T.
Tikhonchuk
, and
S.
Bouquet
, “
Compressible Rayleigh-Taylor instabilities in supernova remnants
,”
Phys. Plasmas
302
,
4661
4670
(
2004
).
11.
H. I.
Anderson
and
E. N.
Dahl
, “
Gravity-driven flow of a viscoelastic liquid film along a vertical wall
,”
J. Phys. D
32
,
1557
1562
(
1999
).
12.
A. R.
Piriz
,
J.
Sanz
, and
L. F.
Ibañez
, “
Rayleigh-Taylor instability of steady ablation fronts: The discontinuity model revisited
,”
Phys. Plasmas
4
,
1117
1126
(
1997
).
13.
S.
Chandrasekhar
,
Hydrodynamics and Hydromagnetic Stability
(
Dover
, New York,
1961
). pp.
428
480
.
14.
T. E.
Faber
,
Fluid Dynamics for Physicists
(
Cambridge U. P.
, Cambridge,
1995
).
15.
E.
Fermi
,
The Collected Papers of Enrico Fermi
, edited by
E.
Amaldi
 et al (
The University of Chicago Press
, Chicago,
1962
), Vol.
2
, article No. 243, pp.
813
815
.
16.
K. O.
Mikaelian
, “
Effect of viscosity on Rayleigh-Taylor and Richtmyer-Meshkov instabilities
,”
Phys. Rev. E
47
,
375
383
(
1993
).
17.
A. R.
Piriz
and
R. F.
Portugues
, “
Hydrodynamic instabilities in an ablation front
,”
Plasma Phys. Controlled Fusion
46
,
935
950
(
2004
).
18.
L. D.
Landau
and
E. M.
Lifshitz
,
Fluid Mechanics
(
Pergamon, Oxford
,
1987
), 2nd ed.
19.
R.
Hide
, “
The character of the equilibrium of an incompressible heavy viscous fluid of variable density: An approximate theory
,”
Proc. Cambridge Philos. Soc.
51
,
179
201
(
1955
).
20.
W. H.
Ride
, “
The effects of surface tension and viscosity on the stability of two superposed fluids
,”
Proc. Cambridge Philos. Soc.
57
,
415
425
(
1961
).
21.
A. R.
Piriz
,
J. J.
Lopez Cela
,
O. D.
Cortazar
,
N. A.
Tahir
, and
D. H. H.
Hoffmann
, “
Rayleigh-Taylor instability in elastic solids
,”
Phys. Rev. E
72
,
056313
1
(
2005
).
22.
R.
Bellman
and
R. H.
Pennington
, “
Effects of surface tension and viscosity on Taylor instability
,”
Q. Appl. Math.
12
,
151
162
(
1954
).
23.
Hide (Ref. 19) independently found the same formula by using a variational method. After this publication Ride (Ref. 20) pointed out that Hide’s derivation of Eq. (23) was in error and published a corrected version that resulted in a less accurate approximation than Eq. (23). More recently, Mikaelian (Ref. 16) obtained Eq. (23) by using a moment equation approach that used the inviscid velocity field approximation that we have used here and that was also used by Hide and Ride [Eq. (19) with qk]. Mikaelian has shown that the other approximations introduced in Hide’s derivation were consistent with using such a velocity field and demonstrated that Hide’s derivation was actually correct.
AAPT members receive access to the American Journal of Physics and The Physics Teacher as a member benefit. To learn more about this member benefit and becoming an AAPT member, visit the Joining AAPT page.