Abstract
Computer simulations of bubble collapses are performed under conditions of multibubble sonoluminescence for various acoustic amplitude(p_a) and the ambient bubble radius (R_0). The bubble temperature at the collapse is plotted on the R_0-p_a phase space. For experiments using a horn immersed into water, bubbles move in the R_0-p_a phase space from the upper part of Fig.1 to the lower part because bubbles created near the horn tip flow away from the horn tip where the acoustic amplitude is large. It is seen in Fig.l that the bubble temperature at the collapse is almost constant from 10 bar to 5 bar(7,000 K). It is why a single temperature can be determined for each experiment of multibubble sonoluminescence by the shape of the metal emission lines or by the chemical rate thermometry. For experiments using a standing wave of ultrasound in water, bubbles move in p_a-R_0 space from the lower part of Fig.2 to the upper part because bubbles move by the Bjerknes force toward the pressure antinode. However, bubbles can not enter into the region above the thick line because the direction of the Bjerknes force is reversed at the thick line. Thus in this case, SBSL like bubbles can be observed as seen in Fig.2.
