Long-range correlations in sedimentation

P. N. Segrè, E. Herbolzheimer, P. M. Chaikin

    Research output: Contribution to journalArticlepeer-review


    Using particle image velocimetry we have measured the sedimentation dynamics of non-Brownian colloidal spheres over a wide range of low concentrations (φ ≤ 0.05) and sample cell sizes W. Fluctuations in the settling velocity show universal large-scale finite-range correlations, in the form of swirls, which depend simply on volume fraction and particle radius and follow ⟨δVz(0) δVz(z)⟩1/2≃2.0Vsed φ1/3 exp(−z/2ξ), where ξ≃20aφ−1/3. In turn, the predicted divergence of the velocity variance with increasing cell size W is cut off in a universal way as W exceeds the swirl size and is well represented by ⟨δV2z(0)⟩1/2 = 2.0Vsedφ1/3 [1 − exp(−W/60aφ−1/3)].

    Original languageEnglish (US)
    Pages (from-to)2574-2577
    Number of pages4
    JournalPhysical Review Letters
    Issue number13
    StatePublished - Sep 29 1997

    ASJC Scopus subject areas

    • General Physics and Astronomy


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