Abstract: In early research, capture and manipulation of particles were mainly achieved by means of light, electricity and plasma in micro-fabrication and micro-assembly. A new method is proposed using micro-water jet to form water tweezers to capture solid particles and implement position control of micro-particles. This paper analyzes the basic principle of water tweezers, and the discrete element method and smoothed particle hydrodynamics method are employed to establish a solid-liquid coupling model used in analyzing the trapping mechanism. A flow field model is set up to simulate dynamic characteristic of water tweezers based on computational fluid dynamics (CFD). Selection of boundary conditions, initial guess, solver control and convergence strategies of the model are discussed. Velocity and pressure of streamline are predicted and discussed under certain input conditions. Simulation results demonstrate that it is an efficiently theoretical method to eventually trap solid particles by water tweezers.

Key words: Water tweezers , Micro-particle trapping , Computational fluid dynamics (CFD) , Boundary condition