| With the development of computer technology and individual computer performance, the parallel computing technology has become one of the hot research. Because the finite difference time domain method (FDTD) itself is very suitable for parallel computing, and the algorithm is simple to use, as a result of this more and more scholars contribute themselves to the applied research of FDTD method. This paper briefly analyzes the basic theory of the FDTD method, which included the grid partition, numerical dispersion, numerical stability, drive source of loading and setting, and absorbing boundary condition of the theory.For the wide application of ultrasonic technology, whether ultrasonic technology is safe to biological tissue. In view of this problem,the paper uses the Westervelt equation in fluid medium as the spread theory formula in a thermoviscous fluid of ultrasonic. In papers, using FDTD method in fluid acoustic as the basic theory of the numerical simulation of ultrasonic in biological tissue. Considering the absorbing boundary conditions, this paper uses Mur absorbing boundary as absorbing boundary condition of the numerical simulation model, the results confirm that the absorbing boundary was feasibility. In application part,according to the ultrasonic diagnosis figure of human body, this paper sets up the 3d single and composite numerical simulation model of body tissue, and then exposes the single numerical simulation model to acoustic source, with the frequency of the source was 50kHz and 100kHz respectively, the single model that was used in the paper is subcutaneous fatty tissue, kidney tissue and muscle tissue separately.Through analysis the results of simulation, this paper found that the algorithm can achieve the numerical simulation of ultrasonic transmission effectively. Bases on this algorithm, the composite tissue numerical simulation of kidney was carried out, this paper presents numerical simulation figure of the composite tissue in the last. |
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