Hydrodynamic interactions and orthokinetic collisions of porous aggregates in the Stokes regime

M U Babler, J Sefcik, M Morbidelli, J Baldyga

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27 Citations (Scopus)


The hydrodynamic interaction of two neutrally buoyant porous aggregates is investigated under creeping flow conditions for the case where the undisturbed velocity of the surrounding flow field is a linear function of position. In this framework, the relative velocity between two aggregates is given by the deformation of the undisturbed flow expressed through the rate of strain and the angular velocity of the flow field, and by two flow-independent hydrodynamic functions, typically referred to as A and B, which account for the disturbance of the flow field due to the presence of the particles [G. K. Batchelor and J. T. Green, J. Fluid Mech. 56, 375 (1972)]. In the present paper, the analysis of the hydrodynamic interaction that is known for the case of two impermeable, solid particles is extended to the case of porous aggregates by applying Brinkman's equation to describe the flow within the aggregates. A reflection scheme is applied to calculate A and B and the obtained expressions are applied to interpret the orthokinetic aggregation of aggregates in diluted suspensions, where the collision frequency is computed using the method of relative trajectories of a pair of aggregates.

Original languageEnglish
Article number013302
Number of pages17
JournalPhysics of Fluids
Issue number1
Early online date25 Jan 2006
Publication statusPublished - Jan 2006


  • porus material
  • suspensions
  • two-phase flow
  • hydrodynamics


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