Inertial migration of rigid particles in shear-thinning fluids under asymmetric wall slip conditions  

作　　者：K.K.Krishnaram K.Nandakumar Chandran Man Yeong Ha Ranjith S.Kumar 

机构地区：[1]Micro/Nanofluidics Research Laboratory,Department of Mechanical Engineering,College of Engineering Trivandrum(Government of Kerala),Thiruvananthapuram,Kerala 695016,India [2]Large Scale Computational Thermo-Fluid Dynamics Laboratory,School of Mechanical Engineering,Pusan National University,Busan 46241,Republic of Korea

出　　处：《International Journal of Fluid Engineering》2024年第4期125-138,共14页国际流体工程(英文)

摘　　要：The determination of flow-induced equilibrium positions in pressure-driven flows in microchannels is of great practical importance in particle manipulation.In the computational analysis presented in this paper,the inertial ordering of neutrally buoyant rigid spheres in shear-thinning fluid flow through a hydrophobic microchannel is investigated.The combined effect of the viscosity index n of a power-law fluid and fluid slippage at the wall on the lateral focusing of microspheres is examined in detail.Using the finite element method,the Eulerian flow field between partially slipping parallel walls is simulated,and the Lagrangian movement of particles is continuously tracked.The Navier slip model is used to ensure a finite fluid velocity at the wall,and it is tuned by modifying the slip-length.It is observed that inertial particles concentrate at a standard equilibrium position of 0.6 times the channel half-width H,irrespective of fluid slip due to the symmetry of the flow field.However,this equilibrium position shifts closer to the walls as the viscosity index increases;for instance,when n=0.5,particles stabilize at 0.75H.As a consequence of asymmetry in hydrodynamic behavior due to different fluid slippages at the upper and lower walls,the particle migration path is altered.In a channel with a no-slip upper wall and a partially slipping lower wall(β/H=0.4),particles settle closer to the lower wall at 0.8H.Most importantly,the lateral movement of a particle released at a given vertical position can be altered by tailoring the wall hydrophobicity and viscosity index,thus enabling multiple equilibrium locations to be achieved.

关 键 词：EQUILIBRIUM walls RIGID 

分 类 号：TB126[理学—工程力学]