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[摘要]：We report a lobed pattern around an ultrasonically vibrating needle in aqueous suspension film of micro particles. The lobed pattern consists of several lobed water zones in series along the length direction of the vibrating needle, with a boundary in which particle concentration is much higher than that of the suspension before sonication. Particle concentration within the lobed water zones can be reduced to 6% of that before sonication while its value at the boundary is increased to 3.6 times of that before sonication. As the needle vibration becomes strong, the lobed pattern becomes wide then disappears; meanwhile, particle concentration in the lobed water zones decreases to a minimum value, and then increases. After stopping the sonication, the lobed pattern exists for more than ten minutes with gradual increase of particle concentration in the lobed water zones. The acoustic radiation force, which is generated by ultrasonic field in the aqueous suspension film, is responsible for the above phenomena. (C) 2011 Elsevier B.V. All rights reserved. |
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