Experiments and reduced order modeling of symmetry breaking in Rayleigh-Taylor mixing

We report experiments of fingering asymmetry in Rayleigh-Taylor (RT) mixing at an extremely large viscosity ratio (M approximate to 5 x 105) and Rayleigh numbers [Ra similar to 105-(3 x 106)]. Our experiments confirm the asymmetric growth of RT instabilities across an upward moving interface with strong downward fingering. As the Ra increases, the downward fingers reach the bottom boundary faster, resulting in a lower dispersion at the early time. However, this dynamic is not persistent since the system undergoes vigorous mixing after the elongated fingers reach the bottom boundary. A one-dimensional dispersion model is developed to simulate the RT mixing, which predicts the upward-moving front and mixing across the interface.

Automated summary

Experiments were conducted to investigate the fingering asymmetry in Rayleigh-Taylor mixing with a high viscosity ratio and Rayleigh numbers. The results confirmed the asymmetric growth of instabilities across an upward moving interface with strong downward fingering. The dispersion at early time was lower due to the faster reach of downward fingers to the bottom boundary, but vigorous mixing occurred after the elongated fingers reached the bottom boundary.