Evolution of mixing width induced by general Rayleigh-Taylor instability

Area of Science:

• Fluid Dynamics
• Plasma Physics
• Astrophysical Phenomena

Background:

• Turbulent mixing driven by Rayleigh-Taylor (RT) instability is crucial in natural and engineered systems.
• The mixing width's evolution is a key metric, influenced by acceleration histories and density ratios.
• Existing theories lack comprehensive predictive power for diverse RT flow conditions.

Purpose of the Study:

• To establish a predictive theory for mixing width evolution in general RT flows.
• To account for complex acceleration histories and varying density ratios.
• To explain observed differences in mixing front behavior.

Main Methods:

• Developed a theory based on the conservation principle.
• Incorporated asymmetry of volume-averaged density fields.
• Validated against diverse experimental data covering various acceleration profiles and density ratios.

Main Results:

• The established theory successfully reproduces all documented experimental results for RT instability.
• It demonstrates the theory's applicability across constant, impulsive, oscillating, and complex acceleration histories.
• The theory explains the sensitivity of mixing front evolution to density field asymmetry.

Conclusions:

• A unified theory for predicting mixing width evolution in RT flows has been established.
• The theory provides a framework for understanding mixing dynamics under varied conditions.
• Density field asymmetry is identified as a critical factor influencing mixing front behavior.