Modeling of focused acoustic beams with varied aperture angles using lattice Boltzmann method

High-intensity focused ultrasound(HIFU) has been demonstrated to be a novel technique of noninvasive targeted therapy. Considering of the deficiency in acoustic field modeling of the traditional Khokhlov-ZabolotskayaKuznetsov(KZK) and spheroidal beam equation(SBE) equations, the lattice Boltzmann method(LBM) often used in fluid mechanics with mesoscopic characteristics, is employed to simulate the acoustic field of focused ultrasound. With the 2-diemsnison 9-speed(D2 Q9) lattice, the LBM model is constructed by axisymmetric flow equations in cylindrical coordinates and boundary schemes of focused transducer, and the adjustment of relaxation time is also conducted to realize parameter optimization. The calculations using the proposed LBM model are performed for two focused transducers with different aperture angles, and also compared with the results of the KZK and SBE models. It shows that the LBM model can describe the mechanism of ultrasound excitation and propagation, providing the distribution of acoustic field from the view of fluid mechanics with a clear physical meaning. Additionally, the calculation process of LBM is not affected by the aperture angle of the focused transducer. The proposed LBM exhibits good application potential in theoretical analysis and numerical simulation of acoustic field for HIFU therapy.