JKU Linz, Austria
Finite-size buoyancy-free particles in Poiseuille flow exhibit unexpected behaviour. Segre and Silberberg () found that particles tend to migrate towards an off-centre equilibrium position.
In this study we revisit this phenomenon by means of an immersed boundary method incorporated into the framework of two-dimensional lattice Boltzmann simulations. The resulting numerical model is capable of resolving the interaction between a freely moving single circular particles and the surrounding fluid flow. In case of a fixed particle this simulation methodology agrees well with classical finite volume simulations and literature data. In case of a freely moving particle, a whole set of channel Reynolds numbers and particle to channel diameter ratios is considered. The calculations recover the correct trends of lateral particle motion towards an equilibrium position.
Based on a detailed evaluation of the velocity and pressure disturbance fields, potential physical reasons for this behaviour are discussed. In order to study the influence of velocity profile curvature, the Poiseuille flow configuration is compared to particle motion in constant shear Couette flow. In addition, the influence of the particle’s rotational degree of freedom is highlighted. It can be shown that lateral particle migration can be linked to the disturbance fields induced by the suspended particle.
Finally, an outlook on the incorporation of deformability of the immersed particle is given. This will lead to the investigation of blood cell behaviour in small capillaries.