Numerical Simulation Of Flow Behavior Of Suspended Particles In Hemoperfusion Device

As an important medical consumable in the field of blood purification,the adsorbent particles(Polystyrene divinylbenzene)in the hemoperfusion device will aggregate in the filter at the end of the venous in a suspension state under the action of fluid.In view of the movement of the internal flow field in the inner runner of the hemoperfusion device during clinical use,the corresponding hydrodynamic model is established and solved.The suspension motion of adsorbent particles in the mixed flow field is simulated and analyzed,which provides guidance for the optimization of the structure of the hemoperfusion device and its clinical use.The main research work and achievements include:The porous medium model and suspended particle model are established to solve and analyze.By comparing the two theoretical equations,it can be seen that the porous medium model only describes the motion characteristics of fluid,while the suspended particle model not only describes the motion characteristics of fluid,but also describes the suspension and rolling behavior of particles in the fluidization process,as well as the interaction between blood and particles;CFD coupled with EDEM is used to simulate the mixed flow field in the inner runner with different adsorbent loads.The pressure drop simulated is in good agreement with the experimental pressure drop.The radial distribution of particle velocity and solid holdup is in good agreement with the literature values.Come to conclusion: Compared with the porous media model,the pressure drop at the inlet and outlet of suspended particle model is more consistent with the experimental data.In the suspended particle model,the influence of inlet velocity on the mixed flow field in the inner runner is analyzed.When the inlet boundary conditions are changed in the EulerLagrange numerical solution model,the constant and fluctuating inlet boundary conditions are simulated respectively.It is found that at constant and fluctuating inlet velocities,when the inlet velocities are large,the particles will accumulate in large numbers in the filter at the venous end under the action of fluid.Under the fluctuating inlet velocity,when the inlet velocity is small,the particle velocity fluctuates obviously in the axial and radial distribution,and the particle appears obvious suspension and rolling motion.Euler-Euler was used to solve the mixed flow field in the inner runner.At different inlet velocities,a small number of particles were found to have a rapid suspension and roll motion at the filter at the artery end.Most of the particles were located at the filter at the venous end under the action of fluid.It is concluded that under the Euler-Euler model,the fluctuating inlet velocity is chosen as the boundary condition of the inlet,which can accurately show the suspension and rolling motion of suspended particles in the mixed flow field,and is conducive to the full contact between blood and adsorbent particles.Under the Euler-Lagrange and the Euler-Euler suspended particle hydrodynamic model,the effects of the interaction between phases on the particle velocity and solid holdup distribution are simulated and calculated by the free drag model,Defilice drag force model,Ergun and Wenyu drag force model.The results show that under the discrete phase model,the effects of different interphase interaction models on the particle solid holdup distribution are small,but on the velocity distribution.The degree distribution has different effects.In the homogeneous suspended particle hydrodynamic model,the particle velocity first increases,then decreases,and finally tends to be stable,which is different from that in the discrete phase model.It is found that the particle velocity in the homogeneous phase model is larger than that in the discrete phase model,and the homogeneous phase model can accurately describe the suspension motion of the mixed flow field.conclusion: under the homogeneous model,the drag force of the fluid on the particles is analyzed.The pressure drop at the inlet and outlet of the inner channel is in good agreement with the experimental pressure drop,and the particle velocity is relatively large near the wall.It is concluded that the Euler-Euler model and the Freestream equation drag model can better describe the mixed flow field in the inner channel of the irrigation device.The effects of particle properties(particle density,particle radius)on the mixed flow field in the inner runner are analyzed.The simulation results show that the particle suspension rolling motion in the inner runner can be better presented when the particle density is greater than the blood density by using the Euler-Lagrange suspended particle numerical solution model.Under the Euler-Euler suspended particle model,the particle density affects the flow in the mixed flow field in the inner runner.Velocity of body,particle velocity and pressure drop of inlet and outlet have great influence.Under the Euler-Lagrange numerical model,the influence of particle radius on the mixing flow field in the inner runner is not obvious;under the Euler-Euler suspended particle model,the influence of particle radius on the mixing flow field in the inner runner is obvious.It is concluded that the Euler-Euler phase model is advantageous to describe the motion state of the mixed flow field from the point of view of particle properties;when the particle density is greater than the blood density,it is advantageous to the suspension rolling motion of particles;and the larger the particle radius,the more disadvantageous to the suspension and rolling motion of particles.