Vishneva

Verification of an interaction model of ultrasonic oscillatory system with biological tissues developed in COMSOL Multiphysics was carried out. It was shown that calculation results in COMSOL Multiphysics obtained with a use of “Finer” grid (the ratio of the grid step to a minimum transversal section area of a model ≤ 0.3 mm^-1) best of all qualitatively and quantitatively corresponded to practical results. The average relative error of obtained results in comparison with the experimental ones didn't exceed 4.0%. Influence of geometrical parameters (the thickness of load) on electrical admittance of ultrasonic oscillatory system interacting with biological tissues was investigated. It was shown that increase in the thickness of load within the range from 0 to 95 mm led to decrease in calculated values of natural resonance frequency of longitudinal fluctuations and electrical admittance from 26,58 to 26,35 kHz and from 0,86 to 0,44 mS.

The article describes a method of calculation of electrical admittance values of a low-frequency ultrasonic oscillatory system with a piezoceramic electro-acoustic transducer in interaction with biological tissues with an allowance for geometry and acoustic characteristics in COMSOL Multiphysics. Using this method, values of natural resonance frequencies of longitudinal oscillations and electrical admittance of the system at various geometry of loading were calculated. Possibilities of using the proposed method and a model with simplified geometry under the assumption of isotropy of the elements materials for calculation of natural resonance frequencies of longitudinal oscillations and electrical admittance of the system were also shown.