We cordially invite you to an extra CRC 1114 seminar lecture:

Tomer Goldfriend, Tel Aviv University, gives an extra talk on Wednesday, April 20th, 3.00 pm, room 1.4.31 (E3) Physics Building, Arnimallee 14, on

"Hydrodynamic interaction between two forced objects of arbitrary shape."

Abstract:

We study the relative motion of two arbitrarily shaped objects, caused by their hydrodynamic interaction as they are forced through a viscous fluid. In the limit of zero Reynolds number, it is well known that the hydrodynamic interaction between a pair of rigid spheres in an unbounded fluid does not produce relative translation. I will present two general results, which underline the difference between the dynamics of symmetric and asymmetric configurations:

(a) Using symmetry-based criteria we show that the breaking of inversion symmetry by boundaries of the system accounts for the interactions between two spheres, as observed in experiments. We also provide new predictions for interactions in other object configurations near obstacles.

(b) We quantify the time-dependent relative translation of two self-aligning objects of irregular shape, where the interplay between the orientational interaction and the translational one, in most cases, leads over time to repulsion between the two objects.

If time will allow, I will briefly present the effect of these interactions on sedimentation of irregular objects.

[1] T. Goldfriend, H. Diamant and T. A. Witten, Phys. Fluids 27, 123303 (2015)

[2] T. Goldfriend, H. Diamant and T. A. Witten, arXiv:1512.01649 (2016)