### Abstract

Single-mode Rayleigh-Taylor instability is experimentally studied in low Atwood number fluid systems. The fluids are contained in a tank that travels vertically on a linear rail system. A single-mode initial perturbation is given to the initially stably stratified interface by gently oscillating the tank in the horizontal direction to form standing internal waves. A weight and pulley system is used to accelerate the fluids downward in excess of the earth's gravitational acceleration. Weight ranging from 90 to 450 kg produces body forces acting upward on the fluid system equivalent to those produced by a gravitational force of 0.33-1.35 times the earth's gravity. Two fluid combinations are investigated: A miscible system consisting of a salt water solution and a water-alcohol solution; and an immiscible system consisting of a salt solution and heptane to which surfactant has been added to reduce the interfacial tension. The instability is visualized using planar laser-induced fluorescence and is recorded using a video camera that travels with the fluid system. The growth in amplitude of the instability is determined from the digital images and the body forces on the fluid system are measured using accelerometers mounted on the tank. Measurements of the initial growth rate are found to agree well with linear stability theory. The average of the late-time bubble and spike velocities is observed to be constant and described by U_{ave} = 0.22( √∏AG/k(1 + A) + √∏AG/k(1 - A)), where A is the Atwood number, k is the wave number, and G is the apparent gravity of the fluid system (i.e., the fluid system acceleration minus the earth's gravity).

Original language | English (US) |
---|---|

Pages (from-to) | 1263-1273 |

Number of pages | 11 |

Journal | Physics of Fluids |

Volume | 13 |

Issue number | 5 |

DOIs | |

State | Published - May 2001 |

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### ASJC Scopus subject areas

- Fluid Flow and Transfer Processes
- Computational Mechanics
- Mechanics of Materials
- Physics and Astronomy(all)
- Condensed Matter Physics

### Cite this

*Physics of Fluids*,

*13*(5), 1263-1273. https://doi.org/10.1063/1.1359762

**Experimental study of Rayleigh-Taylor instability : Low atwood number liquid systems with single-mode perturbations.** / Waddell, J. T.; Niederhaus, C. E.; Jacobs, Jeffrey W.

Research output: Contribution to journal › Article

*Physics of Fluids*, vol. 13, no. 5, pp. 1263-1273. https://doi.org/10.1063/1.1359762

}

TY - JOUR

T1 - Experimental study of Rayleigh-Taylor instability

T2 - Low atwood number liquid systems with single-mode perturbations

AU - Waddell, J. T.

AU - Niederhaus, C. E.

AU - Jacobs, Jeffrey W

PY - 2001/5

Y1 - 2001/5

N2 - Single-mode Rayleigh-Taylor instability is experimentally studied in low Atwood number fluid systems. The fluids are contained in a tank that travels vertically on a linear rail system. A single-mode initial perturbation is given to the initially stably stratified interface by gently oscillating the tank in the horizontal direction to form standing internal waves. A weight and pulley system is used to accelerate the fluids downward in excess of the earth's gravitational acceleration. Weight ranging from 90 to 450 kg produces body forces acting upward on the fluid system equivalent to those produced by a gravitational force of 0.33-1.35 times the earth's gravity. Two fluid combinations are investigated: A miscible system consisting of a salt water solution and a water-alcohol solution; and an immiscible system consisting of a salt solution and heptane to which surfactant has been added to reduce the interfacial tension. The instability is visualized using planar laser-induced fluorescence and is recorded using a video camera that travels with the fluid system. The growth in amplitude of the instability is determined from the digital images and the body forces on the fluid system are measured using accelerometers mounted on the tank. Measurements of the initial growth rate are found to agree well with linear stability theory. The average of the late-time bubble and spike velocities is observed to be constant and described by Uave = 0.22( √∏AG/k(1 + A) + √∏AG/k(1 - A)), where A is the Atwood number, k is the wave number, and G is the apparent gravity of the fluid system (i.e., the fluid system acceleration minus the earth's gravity).

AB - Single-mode Rayleigh-Taylor instability is experimentally studied in low Atwood number fluid systems. The fluids are contained in a tank that travels vertically on a linear rail system. A single-mode initial perturbation is given to the initially stably stratified interface by gently oscillating the tank in the horizontal direction to form standing internal waves. A weight and pulley system is used to accelerate the fluids downward in excess of the earth's gravitational acceleration. Weight ranging from 90 to 450 kg produces body forces acting upward on the fluid system equivalent to those produced by a gravitational force of 0.33-1.35 times the earth's gravity. Two fluid combinations are investigated: A miscible system consisting of a salt water solution and a water-alcohol solution; and an immiscible system consisting of a salt solution and heptane to which surfactant has been added to reduce the interfacial tension. The instability is visualized using planar laser-induced fluorescence and is recorded using a video camera that travels with the fluid system. The growth in amplitude of the instability is determined from the digital images and the body forces on the fluid system are measured using accelerometers mounted on the tank. Measurements of the initial growth rate are found to agree well with linear stability theory. The average of the late-time bubble and spike velocities is observed to be constant and described by Uave = 0.22( √∏AG/k(1 + A) + √∏AG/k(1 - A)), where A is the Atwood number, k is the wave number, and G is the apparent gravity of the fluid system (i.e., the fluid system acceleration minus the earth's gravity).

UR - http://www.scopus.com/inward/record.url?scp=0035340671&partnerID=8YFLogxK

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U2 - 10.1063/1.1359762

DO - 10.1063/1.1359762

M3 - Article

AN - SCOPUS:0035340671

VL - 13

SP - 1263

EP - 1273

JO - Physics of Fluids

JF - Physics of Fluids

SN - 0031-9171

IS - 5

ER -