Dresden 2014 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 40: Poster - Quantum Systems/ Stat. Phys./ Diffusive Process

DY 40.30: Poster

Thursday, April 3, 2014, 17:00–19:00, P3

Statistical analysis of trajectories of sedimenting beads in a active fluid — •Levke Ortlieb, Matthias Mußler, Christian Wagner, and Thomas John — Universität des Saarlandes, Experimentalphysik 7.2, 66123 Saarbrücken, Germany

Aqueous suspensions of life-forms have existed on earth since the very beginning of life. All cellular life is characterized by metabolism and requires a continuous assimilation of food or light as its energy source. Locomotion favors the admission of these materials and raises survival probability.

Here we present details on an experimental setup to investigate the locomotion of the green alga chlamydomonas reinhardtii and in particular the sedimentation of micro-spheres of different diameters in a Hele-Shaw-flow environment. The alga has two flagella, a diameter of 10 µm and swims as a puller with approximately 50 µm/s. We present extracted statistical properties of the suspended, passive bead positions, e.g. the mean square displacement or the probability density function of positions. We will compare our results from the microswimmer suspensions with the Brownian motion characteristics of sedimenting particles in very dilute systems and the characteristics in passive sedimenting particles at higher volume concentrations. In our microswimmer suspensions as well as in the sedimentation at higher volume concentrations, the hydrodynamic interaction becomes important and a non-Brownian behavior can be observed.