Translations:Ghost reflection/4/en

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On both sides of the shot point (i.e., above and below it), the pressure starts out as a high positive value, and the particle velocity starts out at a large magnitude. There is a polarity difference, however, between the particle velocity above the shot and the particle velocity below the shot because the explosion forces material away from the shot point. Therefore, we must consider particle velocity as a directional quantity. According to one convention, the particle velocity of the downgoing explosive wave is taken as negative, and the particle velocity of the upgoing explosive wave is taken as positive. Thus, the energy flux of the upgoing wave from the explosion is the negative of the energy flux of the downgoing explosive wave because the energies of the two waves are flowing in opposite directions. In summary, the explosion produces both (1) an upgoing wave (positive particle velocity, positive pressure), and (2) a downgoing wave (negative particle velocity, positive pressure).