Berlin 2012 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 22: Posters I

DY 22.20: Poster

Wednesday, March 28, 2012, 17:00–19:00, Poster A

Motions of aligned object with adjustable chiralities in the stirring-driven flow under the low Reynolds number condition. — •Sung-chih Su and Peilong Chen — No.300, Jhongda Rd., Jhongli City, Taoyuan County 32001, Taiwan (R.O.C.)

Chiral structures of organisms or molecules influence their migration. To study the relation between the structure and the dynamic of a chiral object, we have observed the motion of a chiral sample which moves in a driven flow under the low Reynolds number condition (Re ~0.1). The sample is a three-piece *H* shape object (size is 2cm) whose center stick always aligns in the vertical direction. A vertical rod that revolves in a cylindrical container (radius=10cm) stirs the liquid inside (depth=20cm). On the top view, this sample has the *X* shape with a crossing angle ranging from -90 to 90 degrees, and an intrinsic orientation was defined by the angle bisector. The handedness of a sample depends on the sign of the crossing angle. Under the temperature control and density match, the trajectories in the frame rotating with driving rod are steady closed loops on the horizontal plane with their size expanding with the absolute value of the crossing angle. A pair of samples with opposite handedness has the same spin frequency with the driving rod. Their intrinsic orientations also have the same dependence on spatial position except for the absolute value of the crossing angle ranging between 70 to 85 degrees in which the opposite handed ones have a difference in their intrinsic orientations. We also observe the coupled trajectories and spins of two chiral objects.