Simulation of pulsed ultrasonic diffraction in viscous fluids using transmission line matrix method

Area of Science:

• Acoustics
• Computational Physics
• Fluid Dynamics

Background:

• Ultrasonic fields in viscous media are affected by diffraction, attenuation, and dispersion.
• Existing Transmission Line Matrix (TLM) methods have limitations in simulating both attenuation and diffraction simultaneously.

Purpose of the Study:

• To develop and validate an enhanced Transmission Line Matrix (TLM) method capable of simulating ultrasonic wave propagation, including both diffraction and attenuation, in viscous fluids.
• To analyze the influence of attenuation and dispersion on ultrasonic pulse waveforms.

Main Methods:

• Incorporated quadratic frequency-dependent absorption and dispersive effects of viscous fluids into the TLM method.
• Utilized Fourier transform to decompose waves into frequency components, processing each separately.
• Applied the model to simulate ultrasonic fields diffracted by a circular transducer emitting short pulses in a viscous medium.

Main Results:

• The numerical results demonstrate the significant impact of attenuation on ultrasonic wave shapes.
• Dispersion effects were shown to influence the arrival times of the ultrasonic pulses.
• Waveforms were successfully interpreted in terms of plane and edge wave components.

Conclusions:

• The enhanced TLM method provides a comprehensive approach to modeling ultrasonic wave propagation in viscous media.
• The study highlights the critical roles of attenuation and dispersion in shaping ultrasonic waveforms and arrival times.