![]() The synergistic effect of acoustic frequency and vessel elasticity had also been investigated, since the circumferential stress showed either an increasing trend or a decreasing one versus the vessel rigidity at difference acoustic frequencies. ![]() The more rigid the vessels were, the more damped the bubble oscillations. The fluid shear and circumferential stresses peaked at frequencies above the bubble’s resonance frequency. The bubble resonance frequency increased as the rigidity of a flexible vessel increased. As the frequency changed, the microbubble oscillated with the highest amplitude at its resonance frequency which was different from the resonance frequency of an unbound bubble. The fluid shear and circumferential stresses acting on the vessel varied with time and location. The effects of acoustical parameters, vessel viscoelasticity and rigidity, vessel/bubble size and off-center bubbles on bubble behaviour and stresses on the vessel were investigated. In this study the fluid shear and circumferential stresses were evaluated as indicators of the mechanical stresses. This work was validated with previous experimental results and enabled us to evaluate the microbubbles’ behaviour and the resulting mechanical stresses induced on the vessel walls. Two bubble models with the assumption of a spherical symmetric bubble and a simple asymmetrical bubble were simulated. In this work, we developed a comprehensive three dimensional model of a confined microbubble inside a vessel while considering the bubble shell properties, blood viscosity, vessel wall curvature and the mechanical properties of the vessel wall. ![]() Therefore, it is important to use sufficiently low pressure amplitudes to avoid rupturing the vessels while still inducing the desired therapeutic effects. These mechanical stresses can produce beneficial therapeutic effects but also induce vessel rupture if the stresses are too high. Ultrasound contrast agents inside a microvessel, when driven by ultrasound, oscillate and induce mechanical stresses on the vessel wall.
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