## 摘要

An experimental study of miscible magnetic fluid motion in a vertical capillary tube is presented. Transporting ferrofluids is dominated by a dimensionless magnetic number Ma, which characterizes the ratio of upward magnetic force to the downward gravity. Two distinct stages of motion, referred to as the sub-critical mode of finite lift and the effective transportation, are identified. These two modes are determined by the values of the sub-critical magnetic number Ma_{sub} and critical magnetic number Ma_{cr} respectively. For the cases of sub-critical mode (Ma_{sub} < Ma < Ma_{cr}), the ferrofluids are lifted to quasiequilibrium heights, which are nearly proportional to the magnetic number Ma. As for the situations of effective transportation (Ma > Ma_{cr}), a penetrating finger of ferrofluids is formed similar to the conventional miscible displacements. A dimensionless proportionality of fingertip velocity v, magnetic number Ma and field distribution profile f_{z} is obtained as v ∼ Ma^{1/2} f_{z} by scaling arguments. This proportional correlation shows a good agreement with the experiments.

原文 | English |
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頁（從 - 到） | 311-317 |

頁數 | 7 |

期刊 | Journal of Mechanics |

卷 | 24 |

發行號 | 4 |

DOIs | |

出版狀態 | Published - 1 一月 2008 |