We study the dynamics of a neutrally buoyant rigid sphere carried by an elastoviscoplastic fluid in a pressure-driven channel flow numerically. The yielding to flow is marked by the yield stress which splits the flow into two main regions: the core unyielded region and two sheared yielded regions close to the walls. The particles which are initially in the plug region are observed to translate with the same velocity as the plug without any rotation/migration. Keeping the Reynolds number fixed, we study the effect of elasticity (Weissenberg number) and plasticity (Bingham number) of the fluid on the particle migration inside the sheared regions. In the viscoelastic limit, in the range of studied parameters (low elasticity), inertia is dominant and the particle finds its equilibrium position between the centreline and the wall. The same happens in the viscoplastic limit, yet the yield surface plays the role of centreline. However, the combination of elasticity and plasticity of the suspending fluid (elastoviscoplasticity) trigger particle-focusing: in the elastoviscoplastic flow, for a certain range of Weissenberg numbers ($\approx 0.5$), isolated particles migrate all the way to the centreline by entering into the core plug region. This behaviour suggests a particle-focusing process for inertial regimes which was not previously found in a viscoelastic or viscoplastic carrying fluid.

我们数值研究了由弹性粘塑性流体在压力驱动的通道流中携带的中性浮力刚性球体的动力学。屈服应力以屈服应力为特征它将流量分成两个主要区域：岩心非屈服区域和靠近壁的两个剪切屈服区域。观察到最初在塞子区域中的颗粒以与塞子相同的速度平移，而没有任何旋转/迁移。在保持雷诺数不变的情况下，我们研究了流体的弹性（魏森伯格数）和可塑性（宾厄姆数）对剪切区内粒子迁移的影响。在粘弹性极限内，在所研究的参数范围内（低弹性），惯性占主导地位，粒子在中心线和壁之间找到平衡位置。粘塑性极限也一样，但屈服面起着中心线的作用。然而，$\approx 0。5$），孤立的颗粒通过进入芯塞区域而一直迁移到中心线。此行为表明惯性范围内的粒子聚焦过程是以前在粘弹性或粘塑性携带流体中未发现的。