Hydrodynamic interactions between two forced objects of arbitrary shape. I. Effect on alignment

Tomer Goldfriend, Haim Diamant, Thomas A. Witten

Research output: Contribution to journalArticlepeer-review


We study the properties and symmetries governing the hydrodynamic interaction between two identical, arbitrarily shaped objects, driven through a viscous fluid. We treat analytically the leading (dipolar) terms of the pair-mobility matrix, affecting the instantaneous relative linear and angular velocities of the two objects at large separation. We prove that the instantaneous hydrodynamic interaction linearly degrades the alignment of asymmetric objects by an external time-dependent drive [B. Moths and T. A. Witten, "Full alignment of colloidal objects by programed forcing," Phys. Rev. Lett. 110, 028301 (2013)]. The time-dependent effects of hydrodynamic interactions are explicitly demonstrated through numerically calculated trajectories of model alignable objects composed of four stokeslets. In addition to the orientational effect, we find that the two objects usually repel each other. In this case, the mutual degradation weakens as the two objects move away from each other, and full alignment is restored at long times.

Original languageEnglish
Article number123303
JournalPhysics of Fluids
Issue number12
StatePublished - 1 Dec 2015

All Science Journal Classification (ASJC) codes

  • Computational Mechanics
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering
  • Fluid Flow and Transfer Processes


Dive into the research topics of 'Hydrodynamic interactions between two forced objects of arbitrary shape. I. Effect on alignment'. Together they form a unique fingerprint.

Cite this