Simulation of nonlinear propagation of biomedical ultrasound using PZFlex and the KZK Texas code
- Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Oxford (United Kingdom)
In biomedical ultrasound nonlinear acoustics can be important in both diagnostic and therapeutic applications and robust simulations tools are needed in the design process but also for day-to-day use such as treatment planning. For most biomedical application the ultrasound sources generate focused sound beams of finite amplitude. The KZK equation is a common model as it accounts for nonlinearity, absorption and paraxial diffraction and there are a number of solvers available, primarily developed by research groups. We compare the predictions of the KZK Texas code (a finite-difference time-domain algorithm) to an FEM-based commercial software, PZFlex. PZFlex solves the continuity equation and momentum conservation equation with a correction for nonlinearity in the equation of state incorporated using an incrementally linear, 2nd order accurate, explicit algorithm in time domain. Nonlinear ultrasound beams from two transducers driven at 1 MHz and 3.3 MHz respectively were simulated by both the KZK Texas code and PZFlex, and the pressure field was also measured by a fibre-optic hydrophone to validate the models. Further simulations were carried out a wide range of frequencies. The comparisons showed good agreement for the fundamental frequency for PZFlex, the KZK Texas code and the experiments. For the harmonic components, the KZK Texas code was in good agreement with measurements but PZFlex underestimated the amplitude: 32% for the 2nd harmonic and 66% for the 3rd harmonic. The underestimation of harmonics by PZFlex was more significant when the fundamental frequency increased. Furthermore non-physical oscillations in the axial profile of harmonics occurred in the PZFlex results when the amplitudes were relatively low. These results suggest that careful benchmarking of nonlinear simulations is important.
- OSTI ID:
- 22492638
- Journal Information:
- AIP Conference Proceedings, Vol. 1685, Issue 1; Conference: 20. international symposium on nonlinear acoustics, Ecully (France), 29 Jun - 3 Jul 2015, 2. international sonic boom forum, Ecully (France), 29 Jun - 3 Jul 2015; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
ACOUSTICS
ALGORITHMS
AMPLITUDES
BEAMS
BENCHMARKS
BIOMEDICAL RADIOGRAPHY
COMPARATIVE EVALUATIONS
CONTINUITY EQUATIONS
DIFFRACTION
EQUATIONS OF STATE
FIBERS
HARMONICS
NONLINEAR PROBLEMS
SIMULATION
T CODES
TRANSDUCERS
ULTRASONIC WAVES
ULTRASONOGRAPHY