Shock wave therapy (SWT) is a physical treatment that uses focused or unfocused shock wave to treat a variety of diseases including plantar fascitis, chronic pain, erectile dysfunction, bone ache, heart disease, and osteoarthritis. Most SWT devices use electrohydraulic or electromagnetic source that results in focused shock waves by a reflector or an acoustic lens. The ballistic SWT device, scaled down in size, consists of a hand piece within which compressed air is used to fire a projectile that strikes a metal applicator placed on the skin.
More reliable measurements and modeling on the pressure field of the device should be conducted in order to clarify the beneficial effect of shock wave.
Many new data on the pressure field of ballistic shock wave were presented by their successful studies although the experimental results were not identical with each other. The origin for different results in those literatures is likely related to the settings on the devices and measurement conditions, which might arouse ambiguity on clarifying physical and biological mechanism.
Pae Kyong Nam, a researcher at the Faculty of Physics, has developed a Lattice Boltzmann model based on mass and momentum conservation equations and Tait equation of state to elucidate propagation behavior of the ballistic shock wave. He has modeled the weak compressible flow with the mass and momentum conservation equations to obtain the macroscopic variables such as density, velocity and pressure. In order to solve the equations mentioned above, he has closed the system with a relation between the pressure and conserved variables by using the Tait equation of state (EOS).
The applicator used in the simulation was a convex shaped applicator with a 15mm diameter, referred to as unfocused, whose effective radius of curvature was 41mm, and the center was extended approximately 0.7mm from the edge.
A simulated pressure waveform is generally in good agreement with the previous experimental results, which has a leading positive phase and a subsequent negative phase.
You can find more information in his paper “Simulation of Acoustical Field of Ballistic Shock Therapy Device by the Lattice Boltzmann Method” in “Physics of Wave Phenomena” (SCI).
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