Further results from microgravity flight experiments on acoustic shaping are discussed. In previous experiments, the authors showed that straight and curved walls could be formed using styrofoam and cereal pellets of arbitrary shape seeded in a sound field in a resonant chamber. The wall shapes corresponded to constant-pressure-amplitude contours of the sound field; however, the walls have multiple stable locations near the nodal planes. Low acoustic energy input found to be sufficient in microgravity. Here the observations are related to predictions of particle and flowfield behavior. For the low-order modes used here, acoustic streaming is an important factor in transporting particles through the chamber. Simulations using multiple harmonics indicates possibilities for constructing and transporting shapes inside the container. Flow visualization supports the streaming predictions. The streaming velocity corresponds to the predicted values for the measured standing wave pressure amplitude. Visualizations of nodal planes show the formation of shapes of specified curvature. G-jitter is of the order of 0.03g, comparable to the peak accelerations due to acoustic radiation force, limits wall formation and control time during each parabola. Complex shapes can be formed with a variety of materials in microgravity. Tailoring the sound field to specific shapes and materials appears to be within reach.
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