Fig. 3.
Sinking velocity and cell coagulation. (A) Sketch of the different phases of the described cell-pairing mechanism. The arrow in the x axis indicates the approximate rate at which each phase takes place for living and dead P. tricornutum cells at 105 cells per liter. A standard shear vertical profile is depicted as a dashed yellow line. It is only below γc that reorientation and pairing occur. g, direction of gravity. (B) Probability density functions (PDFs) of instantaneous sedimentation velocity for living cells (light green) and dead cells (dark green). (C) Coagulation time for diffractometry (circles) and videomicroscopy (squares) experiments. The filled square (■) indicates dead cells. The red line indicates the least-square fit to the measurements, and the dashed line is the theoretical model of Koch and Shaqfeh (23). (Inset) Evolution of the radial distribution function, g(r), obtained in videomicroscopy experiments. Line colors evolve with time from red to yellow. Dashed lines indicate the reference value [g(r) = 1] and the sampling uncertainties.