| ESWL that was borned in 1981 is a great achievement in medical treatment technology domain. For that its characteristics of conveniences for operation, high efficiency for comminution, non-invasive and so on, ESWL has proved to be the first of all treatment methods for stone sufferer. Although ESWL develops very quickly, there are still many factors need to be refined. People developed the basic research in vivo and in vitro in order to get the best comminution effect and lowest side-effect.Non-linearity of shock wave and other casual factors(such as manufacture error, wave fluctuating of discharge voltage)both can bring on the practical focus excursion from geometry focus F2. Measure of pressure by Dornier HM-3shows there is a 6dB area with its landscape orientation size about 15mm in focus area. Nowadays, we usually refers to"-6dB focus area", it means that half of peak voltage is higher than the plus pressure of shock wave, which is also intituled"half peak value focus area". The target of fixed screen should located at geometry center of focus area, by which way , it can satisfied the need of technology and clinic.Further accurate confirming the pressure distribution rule from the mechanisms is still a theoretical problem which deserves to further research. This problem has been studied for more than twenty years, however, we can't get perfect results. So researchers have been improving the numeral simulation method for the pressure field in ESWL. It's our new endeavor to introduce the NND scheme to solve this problem. Our work starts an anyting that is advocated earlier.For that the focused pressure in ESWL is up to several hundreds atmospheric pressure, so the transmit media——water should think to be compressible, and introduce the Tait state-equation. Then the simulation for the pressure field in ESWL can sum up to solve the non-viscid, compressible, unsteady, two-dimension axial symmetry Euler equation.Zhang H.X developed a non-oscillatory, containing No free parameters and Dissipative scheme (NND). Because its characteristics just as simpleness for calculating, strong ability for capturing shock wave and so on, NND Scheme gains widely application. After many years development, this method is more and more mature and used more and more widely. NND scheme and its finite volume scheme applied on unstructured grid solve the difficulty that have to introduce the false viscidity terms including the free parameters in order to limit the fluctuation near the shock wave. By calculating the shock reflection from a wall and flow in 2D wind tunnel with a step, the results show that this method can be used to solve the flow problem about exploding under the water contains shock wave.This paper simulate the one dimension shock wave tube problem by the NND difference-scheme, and calculate the pressure field in ESWL by NND finite volume method. The results of the shock wave tube show that NND difference-scheme is an effective scheme for capturing the shock wave; the results of the pressure field in ESWL show that NND scheme can clearly simulate the transmission of the shock wave in ESWL, and describes the negative pressure phenomenon.
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