Numerical Simulation Study On The Separation Behavior Of Magnetic Particles In Two-Dimensional Tube Flow Under The Effect Of Open Gradient Magnetic Field

With the vigorous development of water conservancy,the accompanying environmental problems,especially the water environment,are increasingly prominent.In addition to the progress of society,people have higher requirements for the environment,especially the quality of the water environment.Based on the state of affairs above,many experts and scholars have started to seek and research to give more efficient and cleaner methods for wastewater treatment.As an efficient and clean physical separation technology,open gradient magnetic separation(OGMS)has gradually come into people’s view and is gradually promoted and applied in environmental engineering,biomedical engineering,and other fields.Therefore,how to enhance the separation capacity of open gradient magnetic separation systems and stimulate the potential of open-gradient magnetic separation technology in the field of water and environmental treatment has become a growing concern.First,we developed a simplified magnetic particle separation process model in an open gradient magnetic separation system based on a unidirectional particle-fluid coupling approach.The effect of magnet geometry configuration on the kinetic behavior of particle capture and capture process in laminar flow is investigated.The results show that the axial alternating arrangement(AAA)of bar magnets possesses a better particle capture capability due to the ability to generate a larger area of strong magnetic force between the magnetic bodies.The results also show that for the lateral alternating arrangement(LCA),the square magnets have the best capture efficiency.Second,we introduced a turbulence model based on the numerical model developed above and investigated the effect of turbulence intensity on particle capture rate.The results show that the lateral dispersion of particles contributes to particle capture in an open-gradient magnetic separation system with a straight channel.The results also show that the increase in turbulence intensity enhances the lateral dispersion of particles and thus contributes to particle capture.These findings can provide a theoretical basis for the design and application of open-gradient magnetic separation systems.When the suspension concentration rises,the particle-to-fluid counteraction is not negligible.To this end,a two-way particle-fluid coupling model is developed in Chapter 4 to investigate the effects of suspension concentration and magnet arrangement on the particlefluid dynamic behavior and particle capture process.The results show that the lateral alternating arrangement(LCA)produces an exclusion zone between the magnets that induces a double eddy structure and thus contributes to particle capture.The results suggest that the generation of double eddy structures is not only related to the concentration of the suspension but also the placement of the magnets,i.e.,the magnetic field strength and distribution.This conclusion implies that it is possible to manipulate the external magnetic field to induce eddy structures and thus facilitate particle capture.The above studies and conclusions can provide theoretical guidance and reference for the application and research of open-gradient magnetic separation technology in water treatment and also show the broad application prospect of open-gradient magnetic separation technology in water environment management.