Numerical investigation of two-microbubble collapse and cell deformation in an ultrasonic field

Numerical investigation of acoustic cavitation and viscoelastic tissue deformation

“…Computations are conducted under the assumptions that the fluid flow and solid motion axisymmetric, and all physical properties for each phases are constant except density. The compressibility effects of water and solid are treated by evaluating the water and solid tissue pressures from the Tait equations, where and , regarding that the volume fraction of water is nearly of the cell tissue [35] . To more accurately consider the high-pressure bubble upon collapse, the bubble pressure is determined from the van der Waals equation for isothermal conditions, where Here, the subscript c denotes the critical state of air bubble and .…”

“…The LS method described in our previous studies for various two-phase flow applications [35] , [36] , [37] is extended to investigate acoustic cavitation and resulting tissue deformation. The unified governing equations for bubble, water and tissue regions are expressed as where Here, are left Cauchy-Green deformation tensor, an elastic stress tensor for neo-Hookean materials, shear elastic modulus, respectively, and is a smoothed Heaviside function that varies linearly along the interface thickness of where h is a grid size.…”