| In the field of modern medicine,virtual surgery simulation system,as an important technology of virtual reality technology,can provide doctors with preoperative training preparation,and help doctors at the same time make surgical plans,and blood is an important part of human body,which will directly affect the operation of the doctor by bleeding.Therefore,the introduction of blood flow model in virtual surgery can not only enhance the verisimilitude,but also let the doctor do blood treatment training before operation,which improves the successful rate of operation.Because the traditional simulation methods have poor performance in showing details,simulation of boundary aliasing,and large amount of calculation,it is difficult to guarantee the real-time problem.Thus,this work combines the advantages of mesh and meshless method to build hybrid model,which improves the realistic flow simulation and real-time target for blood flow simulation in virtual surgery.The main work of this paper are as follows:Firstly,the grid method is used to solve the model.In this process,by analyzing the rheological properties of blood flow,this paper introduces the hemodynamic model.By comparing the advantages and disadvantages of Lagrange method and Eulerian method,the method of solving the flow dynamics model is proposed.However,the solution of the combination of projection and viscosity makes the whole process more complicated.In this regard,this work improves the solution of control equation and the problem of viscosity,so that the whole flow simulation is consistent with its physical characteristics.Secondly,based on the above work,large-scale blood flow is simulated using the meshless method.This work uses FLIP(Fluid-Implicit-Particle)algorithm to map particle velocity to the nodes in the grid,followed by the grid computing for other items.Then,changes of the speed of the grid node such as the amount will plug the particles by linear mapping,and the convection term is solved by particle method.Besides,the FLIP method can be used to solve the problem that the particle distribution is uneven.In this process,the loss of numerical value is eliminated,and efficiency of the whole simulation process is improved.Thirdly,due to the disadvantage of FLIP method with lacked blood flow simulation details,this work uses smoothed particle hydrodynamics(Smoothed Particle,Hydrodynamics,SPH)method to separate blood drops from blood,and builds a unified hybrid model.The model is firstly realized by the simulation of the mass flow using the FLIP method.Then,based on SPH,diffusion interface model is used to calculate the surface tension and the air pressure drops in the splitting process.Finally,the ultimate visual screen space rendering is achieved.Finally,a prototype system of blood flow simulation is constructed.The experimental results show that the algorithm of mixed model can achieve stable calculation,good real-time performance,and strong sense of reality,which is suitable for the virtual surgery simulation system.Furthermore,it improves the reality and immersion of the whole virtual surgery simulation system,and enhances the accuracy of blood flow simulation in operating training,which has wide application prospect. |
