Experimental evidence of deviation from mirror reflection for acoustical shock waves

Area of Science:

• Physics
• Fluid Dynamics
• Acoustics

Background:

• The reflection of plane waves on surfaces follows Snell-Descartes laws (mirror reflection) for linear waves.
• This law is known to break down for nonlinear shock waves at grazing incidence angles.

Purpose of the Study:

• To provide experimental evidence of nonlinear shock wave reflection breakdown at grazing angles.
• To investigate reflection patterns for ultrasonic periodic shock waves in water at small amplitudes.

Main Methods:

• Experiments were conducted using ultrasonic periodic shock waves in water.
• Grazing angles typically ranged from 0 to 7 degrees.
• Results were compared with theoretical predictions via numerical simulations.

Main Results:

• Three distinct reflection patterns were observed, differing significantly from mirror reflection.
• Observed patterns include nonlinear regular reflection, Mach-like reflection, and cases where only the incident shock is visible.
• The study achieved measurements with amplitudes over 100 times smaller than previous experiments in air.

Conclusions:

• Experimental results confirm the breakdown of mirror reflection for nonlinear shock waves at grazing angles.
• The observed phenomena are accurately reproduced by theoretical models and numerical simulations.
• This study advances the understanding of nonlinear wave reflection in fluid dynamics.