Stability of an accelerated shear layer
A fluid shear layer with free boundary conditions is subject to a Kelvin--Helmholtz-like instability. When the shear layer is accelerated by a difference in applied pressures it is also subject to a Rayleigh--Taylor-like instability. The combined action of these instabilities leads to at most one unstable mode at each wavelength, whose behavior depends in detail on fluid parameters, the fluid acceleration and the perturbation wavelength. Typically, at longest wavelengths the instability is essentially of Rayleigh--Taylor form; its behavior resembles the Kelvin--Helmholtz-like mode at shorter wavelengths, near the thickness of the shear layer, cutting off when the Kelvin--Helmholtz-like mode does. At still shorter wavelengths, the shear layer is subject to a Rayleigh--Taylor-like instability. Careful control of fluid parameters could place the most unstable wavelength for Rayleigh--Taylor instability, calculated from viscous theory, in the range of wavelengths where the accelerated shear layer has no unstable mode. However, this may be difficult to achieve in practice. If this can be realized, the most unstable growth rate may be reduced by about an order of magnitude by the presence of shear.
- Research Organization:
- Theoretical Division, Group T-3, University of California, Los Alamos National Laboratory, Los Alamos, New Mexico 87545
- OSTI ID:
- 5797492
- Journal Information:
- Phys. Fluids; (United States), Vol. 29:7
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
SUPERCONDUCTIVITY AND SUPERFLUIDITY
FLUIDS
ACCELERATION
HELMHOLTZ INSTABILITY
RAYLEIGH-TAYLOR INSTABILITY
STABILITY
BOUNDARY CONDITIONS
LAYERS
PRESSURE EFFECTS
PRESSURE GRADIENTS
SHEAR
INSTABILITY
PLASMA INSTABILITY
PLASMA MACROINSTABILITIES
640420* - Fluid Physics- Properties & Structure of Fluids- (-1987)