CN103729555A - Method and device for simulating blood flow and vascular wall effects - Google Patents

Abstract

The invention is applicable to the field of man-machine interaction, and provides a method and a device for simulating blood flow and vascular wall effects. The method includes calculating pressure density, viscous-force density and external-force density of fluid particles in blood vessels by the smooth-particle fluid dynamics method; calculating rebound boundary force applied to boundary particles at the junctions of vascular walls and blood flow by a mass point spring model; integrating the calculated force and upgrading dynamic information of the blood flow and the vascular walls. According to the method, deformation of the vascular walls can be simulated while blood flowing is simulated, the particles located at the junctions can be regarded as the boundary particles in the smooth-particle fluid dynamics method and in the mass point spring model, and more real, real-time and effective interactive information can be provided for a virtual blood vessel operation system through calculation of the rebound boundary force.

Description

A kind of method and apparatus of simulating blood flow and vascular wall effect

Technical field

The invention belongs to field of human-computer interaction, relate in particular to a kind of method and apparatus of simulating blood flow and vascular wall effect.

Background technology

In the simulated blood vessel surgery systems of many operating training and planning, research blood flow and vascular wall interact, thereby simulate truly blood flow and with the interaction of surrounding tissue, can provide in real time for simulated blood vessel surgery systems, effective interactive information, when running into special circumstances, can more efficiently help doctor understand how to take correct action.Thereby the interactional research work of blood flow and vascular wall, has a very important role to evaluation system quality.

Existing simulation blood flow and the interactional method of vascular wall, comprise the method based on particle, it has complicated reticulate texture that independence is stronger and higher performance, therefore be often used in the real time modelling of convection cell, the people such as Muller are applied to flowing of simulate blood in sham operated system Smoothed Particle Hydrodynamics Method (SPH), yet it does not provide interactional solution between blood flow and Deformation structure's (vascular wall), for existing between blood flow and vascular wall in interactional simulated blood vessel surgery systems, can not react really the interactive information of vascular wall and blood flow effect.

Summary of the invention

The object of the present invention is to provide a kind of method of simulating blood flow and vascular wall effect, with solve prior art because of can not blood flow and vascular wall between interact, in simulated blood vessel surgery systems, can not react really the interactive information problem of blood flow and vascular wall effect.

The present invention is achieved in that a kind of method of simulating blood flow and vascular wall effect, and described method comprises:

By Smoothed Particle Hydrodynamics Method, calculate pressure density, viscous force density and the outer force density of endovascular fluid particles;

The boundary force that rebounds that the border particle that uses Mass-spring Model to calculate the intersection that is positioned at vascular wall and blood flow is subject to;

Adopt pressure density, viscous force density, the outer force density of the endovascular fluid particles of calculating described in Runge-Kuntta model integration and be positioned at vascular wall and the boundary force that rebounds that the border particle of the intersection of blood flow is subject to, upgrade the multidate information of described blood flow and vascular wall.

Another object of the embodiment of the present invention is to provide a kind of device of simulating blood flow and vascular wall effect, and described device comprises:

The first computing unit, for calculating pressure density, viscous force density and the outer force density of endovascular fluid particles by Smoothed Particle Hydrodynamics Method;

The second computing unit, the boundary force that rebounds being subject to for the border particle that uses Mass-spring Model to calculate the intersection that is positioned at vascular wall and blood flow;

Updating block, for adopting pressure density, viscous force density, the outer force density of the endovascular fluid particles of calculating described in Runge-Kuntta model integration and being positioned at vascular wall and the boundary force that rebounds that the border particle of the intersection of blood flow is subject to, upgrade the multidate information of described blood flow and vascular wall.

In the present invention, utilize Smoothed Particle Hydrodynamics Method to calculate the pressure density of endovascular fluid particles, viscous force density and outer force density, the boundary force that rebounds that the border particle that uses Mass-spring Model to calculate the intersection that is positioned at vascular wall and blood flow is subject to, thereby make when simulation blood flow is mobile, distortion that can simulated blood vessel wall, in borderline particle, both can regard the border particle in Smoothed Particle Hydrodynamics Method as, can be regarded as again the border particle in Mass-spring Model, by the calculating of the boundary force that rebounds, can provide truer for virtual vascular surgery system, more real-time, more effective interactive information.

Accompanying drawing explanation

Fig. 1 is the realization flow figure of the method for the simulation blood flow that provides of first embodiment of the invention and vascular wall effect;

Fig. 2 is the behavioral characteristics procedure chart that employing Smoothed Particle Hydrodynamics Method that first embodiment of the invention provides solves endovascular fluid particles;

Fig. 3 is the suffered boundary force schematic diagram that rebounds of border particle that first embodiment of the invention provides;

The real-time performance table of the particle obtaining based on Smoothed Particle Hydrodynamics Method that Fig. 4 provides for first embodiment of the invention;

Fig. 5 a is the original state figure of aneurysm model;

Fig. 5 b is the schematic diagram that aneurysm model a large amount of particles after 20 time steps inject aneurysm cavity;

Fig. 5 c is after 50 time steps, the schematic diagram that particle is gushed out from vascular wall;

Fig. 5 d is the aneurysm rupture schematic diagram based on moving three-dimensional method;

The structured flowchart of the simulation blood flow that Fig. 6 provides for second embodiment of the invention and the device of vascular wall effect.

Embodiment

In order to make object of the present invention, technical scheme and advantage clearer, below in conjunction with drawings and Examples, the present invention is further elaborated.Should be appreciated that specific embodiment described herein, only in order to explain the present invention, is not intended to limit the present invention.

When people spend in the Force Feedback Model development of Soft Tissue Deformation model between tissue and virtual unit and real-time, interactive plenty of time and energy, but ignored interactional analog operation between convection cell and Deformation structure, as interaction between blood flow and vascular wall etc.

In fact, simulate truly blood flow and with the interaction of surrounding tissue, can help doctor to understand and how when being subject to intervening, take correct action, in many surgery training and planning system, research blood flow and vascular wall interact evaluation system quality are had a very important role.

Simulation blood flow proposed by the invention and and surrounding tissue, i.e. the interactional method of vascular wall, comprising:

By Smoothed Particle Hydrodynamics Method, calculate pressure density, viscous force density and the outer force density of endovascular fluid particles;

The boundary force that rebounds that the border particle that uses Mass-spring Model to calculate the intersection that is positioned at vascular wall and blood flow is subject to;

Adopt pressure density, viscous force density, the outer force density of the endovascular fluid particles of calculating described in Runge-Kuntta model integration and be positioned at vascular wall and the boundary force that rebounds that the border particle of the intersection of blood flow is subject to, upgrade the multidate information of described blood flow and vascular wall.

The present invention utilizes Smoothed Particle Hydrodynamics Method to calculate the pressure density of endovascular fluid particles, viscous force density and outer force density, the boundary force that rebounds that the border particle that uses Mass-spring Model to calculate the intersection that is positioned at vascular wall and blood flow is subject to, thereby make when simulation blood flow is mobile, distortion that can simulated blood vessel wall, in borderline particle, both can regard the border particle in Smoothed Particle Hydrodynamics Method as, can be regarded as again the border particle in Mass-spring Model, by the calculating of the boundary force that rebounds, can provide truer for virtual vascular surgery system, more real-time, more effective interactive information.

Embodiment mono-:

Fig. 1 shows the realization flow of the method for simulation blood flow that first embodiment of the invention provides and vascular wall effect, and details are as follows:

In step S101, by Smoothed Particle Hydrodynamics Method, calculate pressure density, viscous force density and the outer force density of endovascular fluid particles.

Concrete, generally, the fundamental equation of blood flow motion is to be derived by the mass conservation, momentum conservation and the energy conservation of fluid.We suppose that the temperature of blood flow is almost constant and does not have heat to be input in system.Therefore, energy-balance equation is the same with the equation of mechanical energy balance, and energy conservation causes there is no new independent equation.In addition, particIe system is by maintaining number of particles and single particle mass conservation reaches the mass conservation.Therefore, we can focus on how to solve Navier-Stokes equation, and its momentum conservation formula is:

$\mathrm{\ρ}\frac{\∂\stackrel{\→}{v}}{\∂t}=-\mathrm{\ρ}\stackrel{\→}{V}\·\▿\stackrel{\→}{V}+\mathrm{\μ}{\▿}^2\stackrel{\→}{V}-\▿p+\mathrm{\ρ}\stackrel{\→}{g}---\left(1\right)$

Wherein, ρ is fluid particles density; it is velocity vector field; Appropriate operational symbol

p is pressure;

the power of self, as gravitation; μ is coefficient of viscosity.According to equation (1), can calculate in each time step, viscous force is

pressure is

external force is force density.

Compare with other the method for simulation fluid, smooth particle flux body dynamics SPH method is being used and relatively simple aspect calculating fast.The ultimate principle of smooth particle flux body dynamics SPH is:

$A_S\left(\stackrel{\→}{X}\right)={\mathrm{\Σ}}_j{m}_j\frac{A_j}{{\mathrm{\ρ}}_j}W(\stackrel{\→}{r},h)---\left(2\right)$

Wherein, scalar ?

the scalar potential at place is the weighted sum of the contribution of particles of vicinity.M _jand ρ _jrespectively quality and the density of particle j, and a _jat x _jthe field amount at place.Function

be called satisfied:

the level and smooth kernel of condition, the support radius that wherein h is Smoothed Particle Hydrodynamics Method, δ is Dirac function.

Adopt behavioral characteristics process that Smoothed Particle Hydrodynamics Method solves endovascular fluid particles as shown in Figure 2, can comprise the steps:

In step S201, in unit interval step-length, in the support radius of setting, search the adjacent particles j adjoining with intended particle i.

Under normal conditions, the method for finding proximate particle has three kinds, to the method for approaching method, lists of links and the method based on tree.Adopt lists of links method aspect speed far away faster than approaching in pairs method, and lists of links method is compared with the method based on tree, has higher degree of parallelism.

In step S202, according to smooth particle principle of hydrodynamics, obtain the density p of endovascular intended particle i _iand the pressure density f of particle i _i ^p.

Can adopt the method for two kinds of bulk densities, sue for peace densimetry and continuation densimetry.Summation densimetry can directly apply to the density itself approximate with smooth particle flux body dynamics SPH.Continuing densimetry is the concept of utilizing SPH approximate, introduces the continuity equation changing and estimates density.Although summation densimetry may cause that some boundary effects cause border result inaccurate, it can make mass conservation.Therefore, very convenient in smooth particle flux body dynamics SPH practical application.In this programme, when calculating the density of endovascular intended particle, can be by border, around some Level Set method particles are set reduces boundary effect.

Endovascular fluid particles has three original bulies: quality, position and speed.In the assessment of unit interval step-length, smooth particle flux body dynamics SPH is for assessing density p _jforce density f with the pressure being subject to by particle i, viscous force and external force acting in conjunction generation _i ^p, f _i ^ex, f _i ^v.We can calculate density and the pressure density of particle i by fundamental equation.

${\mathrm{\ρ}}_j={\mathrm{\Σ}}_j{m}_{j}W(\stackrel{\→}{r},h)---\left(3\right)$

${f_i}^p=-\▿p=-{\mathrm{\Σ}}_j{m}_j\left(\frac{p_j+p_j}{2{\mathrm{\ρ}}_j}\right)\▿W(\stackrel{\→}{r},h)---\left(4\right)$

Wherein, p _j, p _ithe pressure that represents respectively particle j and particle i, other parameter and upper same.

In step S203, setting gravitation is unique external force, obtains external force density f _i ^ex.

During using gravitation as unique external force, can be by formula

f _i ^ex=ρ _ig（5）

Calculate outer force density.

In step S204, the sub-dimension calculation viscosity of binding layer viscosity and seed force density f _i ^v.

Concrete, blood particle flux, through small-bore hole or during container in irregular shape (as aneurysm), can not simply be regarded blood as laminar flow, answers binding layer viscosity and sub-particle size to calculate viscosity force density:

${f_i}^v={\mathrm{\Σ}}_j{\mathrm{\ρ}}_j\frac{4\mathrm{\μ}\stackrel{\→}{r}({\stackrel{\→}{V}}_j-{\stackrel{\→}{V}}_i)}{({\mathrm{\ρ}}_j+{\mathrm{\ρ}}_i){|\stackrel{\→}{r|}}^2}\▿W(\stackrel{\→}{r},h)+{\mathrm{\Σ}}_j{\mathrm{\ρ}}_j(\frac{T_j}{{\mathrm{\ρ}}_j^2}+\frac{T_i}{{\mathrm{\ρ}}_i^2})\▿W(\stackrel{\→}{r},h)---\left(6\right)$

Be appreciated that, pressure density, viscous force density and the outer force density of obtaining blood vessel inner fluid particle based on Smoothed Particle Hydrodynamics Method adopting in step S101 be a kind of optional embodiment wherein just, persons skilled in the art can be understood, can also pass through other method, as adopted the state of Euler's method Fluid Computation particle or the motion of employing Finite Element Method Simulation fluid etc.

In step S102, the boundary force that rebounds that the border particle that uses Mass-spring Model to calculate the intersection that is positioned at vascular wall and blood flow is subject to.

Concrete, in this step, adopt the interaction of rebounding between boundary condition imitation blood flow and vascular wall.Under the condition not underspeeding, the border particle of the intersection of vascular wall and blood flow will be positioned at, fluid particles that can blood flow, also the power on the particle on can vascular wall, be decomposed into the power N (x) in the direction vertical with border and the power T(y making progress with borderline phase butt), as shown in Figure 3, the particle suffered boundary force that rebounds in border can be expressed as so:

$F_b=\stackrel{\→}{n}N\left(x\right)T\left(y\right)$

Wherein, N (x), T (y) represent respectively the power of vertical direction and the power of tangential direction; represent the unit vector of the direction of power; X and y be respectively border particle and fluid particles in the vertical direction with tangential direction on distance.

Power N (x) in the wherein said direction vertical with border is specially:

When the distance between border particle and fluid particles is greater than predetermined threshold distance, the power N (x) in the described direction vertical with border is zero;

When border particle and distance between fluid particles be less than or equal to power N (x) in predetermined threshold distance and the described direction vertical with border be less than or equal to border particle spring be connected in during the maximal value of tensile force, the power N (x) in the described direction vertical with border is $\mathrm{\Ψ}\frac{1}{\sqrt{r}}(1-r);$ Described $r=\frac{x}{2h},\mathrm{\Ψ}=\frac{1}{h}(\frac{\left|p\right|}{\mathrm{\ρ}}+{\mathrm{\βV}}_{\mathrm{ab}}*n_b),$ H is the support radius of Smoothed Particle Hydrodynamics Method, and x is the distance between border particle and fluid particles, and p is the mutual pressure in fluid particles a and border, and ρ is particle density, V _abfor the speed of fluid particles a with respect to retive boundary particle b; n _bnormal orientation for border particle b; When fluid particles a and border particle b are when close to each other, β gets 1; When fluid particles a and border particle b are when reverse, β gets 1;

When described N (x) is greater than the maximal value of tensile force in the particle spring connection of border, the power N (x) in the described direction vertical with border is zero.

At design function T(y) time, need to guarantee when fluid particles parallel is during to boundary curve, from these tangential border particles generations make a concerted effort remain unchanged, make the fluid particles can be mobile stably along border.

In step S103, adopt pressure density, viscous force density, the outer force density of the endovascular fluid particles of calculating described in Runge-Kuntta model integration and be positioned at vascular wall and the boundary force that rebounds that the border particle of the intersection of blood flow is subject to, upgrade the multidate information of described blood flow and vascular wall.

Concrete, according to the pressure density of calculated endovascular fluid particles, viscous force density and with the mutual external force producing of border particle, current location and particle density in conjunction with particle, according to Newton second law, calculate acceleration, the speed of each particle, according to the velocity and acceleration value of described calculating, redefine the position of particle.

In order to assess the feasibility of the embodiment of the present invention, carried out corresponding experiment below and verified.

This experiment is carried out time performance assessment for the particle of varying number.First, construct the boundary condition that rebounds after an aneurysm model checking improves, by experiment the impact of the performance of key parameter in this programme is investigated.For key parameter in this programme is had to comparability, all experiments are all to carry out on the computer of same hardware configuration.

Based on Smoothed Particle Hydrodynamics Method, compare with the solution based on grid, it is advantageous that and there is higher performance.Fig. 4 is the real-time performance table of testing described in the embodiment of the present invention, from the table of real-time performance shown in Fig. 4, can find out, when number of particles increases, frame rate declines.When fluid particles reaches about 5000, border particle and reaches about 600, frame rate can remain on about 20fps, and such result can meet the requirement of most of virtual interacting surgery systems.When number of particles is increased to 10000 left and right, frame rate will be less than 10fps.In experimentation, our setup times step-length is 0.1s, support that radius is 0.01, search radius be 0.02 and threshold distance be 0.02.

Fig. 5 a-5d shows an aneurysm model that comprises 6961 particles.Fig. 5 a is the aneurysm under original state.Fig. 5 b is that increasing particle flows into the state in aneurysm cavity after 20 time steps.Fig. 5 c is after 50 time steps, and the repulsive force between border particle and fluid particles surpasses the maximum stretching force of border spring, and it is aneurysm rupture that particle is gushed out from vascular wall, and Fig. 5 d is the aneurysm rupture schematic diagram based on Marching Cubes.In this group experiment, we are set to 0.1s at time step, support that radius is set to 0.01.

It should be noted that some key parameters may affect the effect of this method largely.Normally according to support radius size, search radius, distance threshold are set.

Embodiment bis-:

Fig. 6 shows the structured flowchart of the device of simulation blood flow that second embodiment of the invention provides and vascular wall effect, and details are as follows:

The device of simulating blood flow and vascular wall effect described in the embodiment of the present invention, comprising:

The first computing unit 601, for calculating pressure density, viscous force density and the outer force density of endovascular fluid particles by Smoothed Particle Hydrodynamics Method;

The second computing unit 602, the boundary force that rebounds being subject to for the border particle that uses Mass-spring Model to calculate the intersection that is positioned at vascular wall and blood flow;

Updating block 603, for adopting pressure density, viscous force density, the outer force density of the endovascular fluid particles of calculating described in Runge-Kuntta model integration and being positioned at vascular wall and the boundary force that rebounds that the border particle of the intersection of blood flow is subject to, upgrade the multidate information of described blood flow and vascular wall.

Further, described the first computing unit 601 comprises:

Search subelement, in unit interval step-length, in the support radius of setting, search the adjacent particles j adjoining with intended particle i;

First obtains subelement, for according to smooth particle principle of hydrodynamics, obtains the density p of endovascular intended particle i _iand the pressure density f of particle i _i ^p;

Second obtains subelement, for setting gravitation, is unique external force, obtains external force density f _i ^ex;

Computation subunit, for binding layer viscosity and the sub-dimension calculation viscosity of seed force density f _i ^v.

Concrete, described in search subelement specifically in unit interval step-length, in the support radius of setting, adopt paired mean of access, lists of links method or the method based on tree, search the adjacent particles j adjoining with intended particle i.

Described first obtains subelement specifically for according to smooth particle principle of hydrodynamics, adopts summation densimetry or continues densimetry, obtains the density p of endovascular intended particle i _i.

Further, the second computing unit 602 specifically for:

When the distance between border particle and fluid particles is greater than predetermined threshold distance, the power N (x) in the described direction vertical with border is zero;

When border particle and distance between fluid particles be less than or equal to power N (x) in predetermined threshold distance and the described direction vertical with border be less than or equal to border particle spring be connected in during the maximal value of tensile force, the power N (x) in the described direction vertical with border is $\mathrm{\Ψ}\frac{1}{\sqrt{r}}(1-r);$ Described $r=\frac{x}{2h},\mathrm{\Ψ}=\frac{1}{h}(\frac{\left|p\right|}{\mathrm{\ρ}}+{\mathrm{\βV}}_{\mathrm{ab}}*n_b),$ H is the support radius of Smoothed Particle Hydrodynamics Method, and x is the distance between border particle and fluid particles, and p is the mutual pressure in fluid particles a and border, and ρ is particle density, V _abfor the speed of fluid particles a with respect to retive boundary particle b; n _bnormal orientation for border particle b; When fluid particles a and border particle b are when close to each other, β gets 1; When fluid particles a and border particle b are when reverse, β gets 1;

When described N (x) is greater than the maximal value of tensile force in the particle spring connection of border, the power N (x) in the described direction vertical with border is zero.

Described acquiring unit for according to the pressure density of calculated endovascular fluid particles, viscous force density and with the mutual external force producing of border particle, current location and particle density in conjunction with particle, according to Newton second law, calculate acceleration, the speed of each particle, according to the velocity and acceleration value of described calculating, redefine the position of particle.

Described in the embodiment of the present invention, simulate that described in the device of blood flow and vascular wall effect and embodiment mono-, to simulate the method for blood flow and vascular wall effect corresponding, at this, do not repeat.

The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, all any modifications of doing within the spirit and principles in the present invention, be equal to and replace and improvement etc., within all should being included in protection scope of the present invention.

Claims (10)

1. a method of simulating blood flow and vascular wall effect, is characterized in that, described method comprises:

By Smoothed Particle Hydrodynamics Method, calculate pressure density, viscous force density and the outer force density of endovascular fluid particles;

The boundary force that rebounds that the border particle that uses Mass-spring Model to calculate the intersection that is positioned at vascular wall and blood flow is subject to;

Adopt pressure density, viscous force density, the outer force density of the endovascular fluid particles of calculating described in Runge-Kuntta model integration and be positioned at vascular wall and the boundary force that rebounds that the border particle of the intersection of blood flow is subject to, upgrade the multidate information of described blood flow and vascular wall.

2. method according to claim 1, is characterized in that, described pressure density, viscous force density and the external force density step of calculating endovascular blood flow particle by Smoothed Particle Hydrodynamics Method comprises:

In unit interval step-length, in the support radius of setting, search the adjacent particles j adjoining with intended particle i;

According to smooth particle principle of hydrodynamics, obtain the density p of endovascular intended particle i _iand the pressure density f of particle i _i ^p;

Setting gravitation is unique external force, obtains external force density f _i ^ex;

The sub-dimension calculation viscosity of binding layer viscosity and seed force density f _i ^v.

3. method according to claim 2, is characterized in that, described in unit interval step-length, searches the adjacent particles j step adjoining with intended particle i and be specially in the support radius of setting:

In unit interval step-length, in the support radius of setting, adopt paired mean of access, lists of links method or the method based on tree, search the adjacent particles j adjoining with intended particle i.

4. method according to claim 2, is characterized in that, described according to smooth particle principle of hydrodynamics, obtains the density p of endovascular intended particle i _istep is specially:

According to smooth particle principle of hydrodynamics, adopt summation densimetry or continue densimetry, obtain the density p of endovascular intended particle i _i.

5. method according to claim 1, is characterized in that, described use Mass-spring Model calculates the boundary force that rebounds that the border particle of the intersection that is positioned at vascular wall and blood flow is subject to and is specially:

The power on the border particle of vascular wall and the intersection of blood flow of being positioned at is decomposed into the power N (x) in the direction vertical with border and the power T(y making progress with borderline phase butt), the power N (x) in the wherein said direction vertical with border is specially:

When the distance between border particle and fluid particles is greater than predetermined threshold distance, the power N (x) in the described direction vertical with border is zero;

When border particle and distance between fluid particles be less than or equal to power N (x) in predetermined threshold distance and the described direction vertical with border be less than or equal to border particle spring be connected in during the maximal value of tensile force, the power N (x) in the described direction vertical with border is $\mathrm{\Ψ}\frac{1}{\sqrt{r}}(1-r);$ Described $r=\frac{x}{2h},$ $\mathrm{\Ψ}=\frac{1}{h}(\frac{\left|p\right|}{\mathrm{\ρ}}+{\mathrm{\βV}}_{\mathrm{ab}}*n_b),$ H is the support radius of Smoothed Particle Hydrodynamics Method, and x is the distance between border particle and fluid particles, and p is the mutual pressure in fluid particles a and border, and ρ is particle density, V _abfor the speed of fluid particles a with respect to retive boundary particle b; n _bnormal orientation for border particle b; When fluid particles a and border particle b are when close to each other, β gets 1; When fluid particles a and border particle b are when reverse, β gets 1;

When described N (x) is greater than the maximal value of tensile force in the particle spring connection of border, the power N (x) in the described direction vertical with border is zero.

6. method according to claim 1, it is characterized in that, pressure density, viscous force density, the outer force density of the endovascular fluid particles of calculating described in described employing Runge-Kuntta model integration and be positioned at vascular wall and the boundary force that rebounds that the border particle of the intersection of blood flow is subject to, the multidate information step of upgrading described blood flow and vascular wall is specially:

According to the pressure density of calculated endovascular fluid particles, viscous force density and with the mutual external force producing of border particle, current location and particle density in conjunction with particle, according to Newton second law, calculate acceleration, the speed of each particle, according to the velocity and acceleration value of described calculating, redefine the position of particle.

7. a device of simulating blood flow and vascular wall effect, is characterized in that, described device comprises:

The first computing unit, for calculating pressure density, viscous force density and the outer force density of endovascular fluid particles by Smoothed Particle Hydrodynamics Method;

The second computing unit, the boundary force that rebounds being subject to for the border particle that uses Mass-spring Model to calculate the intersection that is positioned at vascular wall and blood flow;

Updating block, for adopting pressure density, viscous force density, the outer force density of the endovascular fluid particles of calculating described in Runge-Kuntta model integration and being positioned at vascular wall and the boundary force that rebounds that the border particle of the intersection of blood flow is subject to, upgrade the multidate information of described blood flow and vascular wall.

8. install according to claim 7, it is characterized in that, described the first computing unit comprises:

Search subelement, in unit interval step-length, in the support radius of setting, search the adjacent particles j adjoining with intended particle i;

First obtains subelement, for according to smooth particle principle of hydrodynamics, obtains the density p of endovascular intended particle i _iand the pressure density f of particle i _i ^p;

Second obtains subelement, for setting gravitation, is unique external force, obtains external force density f _i ^ex;

Computation subunit, for binding layer viscosity and the sub-dimension calculation viscosity of seed force density f _i ^v.

According to claim 7 device, it is characterized in that, the second computing unit specifically for:

When the distance between border particle and fluid particles is greater than predetermined threshold distance, the power N (x) in the described direction vertical with border is zero;

When border particle and distance between fluid particles be less than or equal to power N (x) in predetermined threshold distance and the described direction vertical with border be less than or equal to border particle spring be connected in during the maximal value of tensile force, the power N (x) in the described direction vertical with border is $\mathrm{\Ψ}\frac{1}{\sqrt{r}}(1-r);$ Described $r=\frac{x}{2h},\mathrm{\Ψ}=\frac{1}{h}(\frac{\left|p\right|}{\mathrm{\ρ}}+{\mathrm{\βV}}_{\mathrm{ab}}*n_b),$ H is the support radius of Smoothed Particle Hydrodynamics Method, and x is the distance between border particle and fluid particles, and p is the mutual pressure in fluid particles a and border, and ρ is particle density, V _abfor the speed of fluid particles a with respect to retive boundary particle b; n _bnormal orientation for border particle b; When fluid particles a and border particle b are when close to each other, β gets 1; When fluid particles a and border particle b are when reverse, β gets 1;

When described N (x) is greater than the maximal value of tensile force in the particle spring connection of border, the power N (x) in the described direction vertical with border is zero.

10. install according to claim 7, it is characterized in that, described acquiring unit for according to the pressure density of calculated endovascular fluid particles, viscous force density and with the mutual external force producing of border particle, current location and particle density in conjunction with particle, according to Newton second law, calculate acceleration, the speed of each particle, according to the velocity and acceleration value of described calculating, redefine the position of particle.

Images