A non-Newtonian fluid simulation method and system for multiphase fluids

Abstract

The present invention discloses a non-Newtonian fluid simulation method and system for multiphase fluid, which belongs to the field of fluid simulation in computer graphics, including: modeling bone structure, including bone shape modeling and porous material modeling inside bone; modeling incompressible fluid based on smooth particle fluid dynamics; unified modeling of Newtonian fluid, shear thinning fluid and shear thickening fluid based on polymer conformation tensor method, and calculation of rheological properties of fluid; based on mixed model, constructing multiphase fluid simulation framework to support two-phase mixed modulation and multiphase fluid dynamics; exporting simulation data and reconstructing fluid surface according to fluid particles, using multiphase fluid rendering technology to render RGB pictures and make fluid animation. The present invention has stable process and realistic visualization effect, and can assist in medical teaching of bone cement surgery or help doctors evaluate the feasibility of surgical plans at low cost.

Description

Technical Field

[0001] The present invention relates to the field of computer graphics fluid simulation, and in particular to a non-Newtonian fluid simulation method and system for multiphase fluids. Background Art

[0002] Non-Newtonian fluids refer to fluids that do not satisfy Newton's experimental law of viscosity, that is, fluids whose shear profit and shear strain rate are not in a linear relationship. Non-Newtonian fluids are commonly found in industrial production processes and in nature, such as various muds, suspensions, and paints in the chemical industry, blood, lymph, and cell fluids in the human body and animals, as well as nanofluids, magnetic fluids, and other fluids whose shear stress and shear strain rate are not in a linear relationship. These non-Newtonian fluids play an important role in high-tech fields such as biomedicine, aerospace, and micro-electromechanical systems, and are closely related to industrial production and the national economy.

[0003] Multiphase fluid refers to a fluid that contains multiple different phases, such as water-gas mixed fluid, water-solid mixed fluid, etc.

[0004] Fluid simulation, physics-based fluid simulation technology can provide visual simulation in complex scenarios. Fluid simulation can be used in various application scenarios, including animated films, engineering simulations, and scientific research. The main goal of fluid simulation is to reproduce the movement and behavior of fluids in a physically realistic way. For the flow of fluids such as bone cement, two technologies are needed: multiphase fluid simulation and non-Newtonian fluid simulation. In the actual bone cement injection surgery process, bone cement configuration often requires the doctor's experience. Simulation visualization technology can show the configuration and flow process of bone cement at a lower cost and more intuitively. Summary of the invention

[0005] In order to solve the above problems, the purpose of the present invention is to provide a non-Newtonian fluid simulation technology for multiphase fluids, namely, a bone cement modulation and dynamic flow computer simulation visualization technology for bone cement filling surgical scenarios, which aims to simulate the modulation and dynamic flow of bone cement in a low-cost, efficient and accurate manner.

[0006] In order to achieve the above technical objectives, the present application provides a non-Newtonian fluid simulation method for multiphase fluids, comprising the following steps:

[0007] Modeling of bone structure, including bone shape modeling and porous material modeling inside the bone;

[0008] Modeling of incompressible fluids based on smoothed particle fluid dynamics;

[0009] Based on the polymer conformation tensor method, Newtonian fluids, shear-thinning fluids and shear-thickening fluids are uniformly modeled to calculate the rheological properties of the fluids.

[0010] Based on the mixture model, a multiphase fluid simulation framework is constructed to support two-phase mixing modulation and multiphase fluid dynamics;

[0011] Export simulation data and reconstruct the fluid surface based on fluid particles, use multiphase fluid rendering technology to render RGB images and create fluid animations.

[0012] Preferably, in the process of modeling the bone structure, the bone shape is surface modeled and a certain volume is filled; for the material inside the bone, porous materials with different porosities are set according to the actual scene requirements to represent healthy bones and osteoporotic bones, thereby completing the modeling of the bone structure.

[0013] Preferably, in the process of modeling the incompressible fluid, a smooth particle system in smooth particle fluid dynamics is constructed, and relevant fluid properties are configured;

[0014] The motion of viscous incompressible fluid is described based on the Navier-Stokes equations, thereby completing the modeling of incompressible fluid.

[0015] Preferably, in the process of calculating the rheological properties of the fluid, a unified description framework for Newtonian fluids, shear-thinning fluids and shear-thickening fluids is defined by introducing a polymer conformation tensor model;

[0016] The viscoelastic stress of the fluid is calculated based on the polymer conformation tensor theory to obtain the rheological properties of the fluid.

[0017] Preferably, in the process of constructing a unified description framework, a viscoelastic stress constitutive model related to the polymer phase tensor is established based on the polymer phase tensor model;

[0018] The polymer phase tensor model is extended to describe shear-thinning non-Newtonian fluids, where nonlinear terms are introduced into the viscoelastic constitutive model to describe the nonlinear shear-related flow behavior.

[0019] Expanding the polymer phase tensor model to describe shear-thickening non-Newtonian fluids, wherein the nonlinear phase tensor model is converted into a combination of a linear phase tensor model and a non-Newtonian viscosity model, eliminating the nonlinear term and instead describing the nonlinear viscosity change;

[0020] A unified configuration is used to control the rheological range of the fluid, which is mainly divided into: Newtonian fluid range, shear thinning range and shear thickening range.

[0021] Preferably, in the process of constructing a multiphase fluid system based on a mixture model, a multiphase fluid simulation framework is constructed through an implicit mixture model;

[0022] Compute the dynamic properties of multiphase fluids, including momentum and phase transport, based on mixture model theory.

[0023] Preferably, in the process of constructing a multiphase fluid simulation framework, the multiphase fluid is modeled based on a mixing model in the multiphase fluid simulation, and the phase tensor model is strongly coupled with the concept of phase volume fraction in the mixing model through polymer concentration parameters.

[0024] Preferably, during the visualization process, simulation data is exported, including particle positions and phase fraction files of the fluid;

[0025] Reconstruct the fluid surface of each frame based on the fluid particle data;

[0026] Design rendering materials for bone shape, bone interior, and fluid, render them into RGB images at different viewing angles, and create animations.

[0027] The present invention discloses a non-Newtonian fluid simulation system for multiphase fluids, characterized in that the system is used to implement a non-Newtonian fluid simulation method for multiphase fluids, and the system comprises:

[0028] The first modeling module is used to model the bone structure, including the bone shape modeling and the porous material modeling inside the bone;

[0029] A second modeling module for modeling incompressible fluids based on smoothed particle fluid dynamics;

[0030] The first data processing module is used to uniformly model Newtonian fluids, shear-thinning fluids and shear-thickening fluids based on the polymer conformation tensor method, and calculate the rheological properties of the fluids;

[0031] The second data processing module is used to construct a multiphase fluid simulation framework based on the mixing model to support two-phase mixing modulation and multiphase fluid dynamics;

[0032] The simulation module is used to export simulation data and reconstruct the fluid surface based on fluid particles, render RGB images using multiphase fluid rendering technology, and create fluid animations.

[0033] The present invention discloses the following technical effects:

[0034] The present invention models bone cement by establishing a constitutive model based on physics, and then performs fluid-solid coupling simulation to obtain simulation results of fluid flow through reasonable bone structure modeling. The method has the advantages of stable process, high efficiency, and visualization effect close to reality. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0036] Figure 1 It is a schematic diagram of the method flow of the present invention;

[0037] Figure 2 The lumbar vertebrae modeling model of the present invention;

[0038] Figure 3 is a comparison of the stability of different methods described in the present invention when mixing phases of different viscosities;

[0039] Figure 4 This is the lumbar vertebrae injection experiment described in the present invention. DETAILED DESCRIPTION

[0040] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. The components of the embodiments of the present application generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application.

[0041] like Figure 1-4As shown, the present invention provides a simulation and visualization method for the modulation and dynamic flow of bone cement in the bone cement injection surgery scene. The method flow includes: first, using 3D software to model the target bone model, including the skeleton shape and the porous material inside the bone; secondly, using the multiphase non-Newtonian fluid simulation algorithm proposed by us to model the bone cement; then, setting the relevant scene parameters, such as the modulation ratio of bone cement, injection angle, injection speed, injection volume, etc., and starting the simulation; finally, exporting the fluid information obtained by simulation, such as the position of fluid particles, phase fraction, etc., and visualizing the flow through fluid surface reconstruction, multiphase fluid rendering and other technologies. In the non-Newtonian fluid simulation algorithm, three key technologies are used: 1. Incompressible fluid calculation framework based on smooth particle fluid dynamics; 2. Non-Newtonian fluid modeling based on polymer conformation tensor method; 3. Multiphase fluid simulation calculation framework based on hybrid model. This method has a stable process and realistic visualization effect, which can assist in medical teaching of bone cement surgery or help doctors evaluate the feasibility of surgical plans at low cost.

[0042] Specifically, the present invention discloses a bone cement modulation and dynamic flow computer simulation visualization method for a bone cement filling surgery scene, which specifically includes the following steps:

[0043] Step (1): Use 3D software, such as Blender, to model the bone shape and internal structure. Use porous materials to model the internal structure of the bone and adjust the porosity according to normal bone and porous bone. Finally, perform particle sampling on the model.

[0044] Step (2): Based on smoothed particle fluid dynamics, the incompressible fluid is first modeled according to the Navier-Stokes equations;

[0045] Step (3): Based on the polymer phase tensor model, a viscoelastic stress constitutive model related to the polymer phase tensor is established;

[0046] Step (4): Extending the polymer phase tensor model to describe shear-thinning non-Newtonian fluids, specifically, introducing nonlinear terms in the viscoelastic constitutive model to describe nonlinear shear-related flow behavior;

[0047] Step (5): Expanding the polymer phase tensor model to describe shear thickening non-Newtonian fluids, specifically, converting the nonlinear phase tensor model into a combination of a linear phase tensor model and a non-Newtonian viscosity model, eliminating the nonlinear term and instead describing the nonlinear viscosity change;

[0048] Step (6): using a unified configuration to control the rheological range of the fluid, which is mainly divided into: Newtonian fluid range, shear thinning range and shear thickening range;

[0049] Step (7): Modeling the multiphase fluid based on the mixing model in the multiphase fluid simulation, strongly coupling the phase tensor model with the concept of phase volume fraction in the mixing model through the polymer concentration parameter, and constructing a two-phase non-Newtonian fluid simulation algorithm;

[0050] Step (8): Prepare the modeling of bone and fluid and simulate it through this method, so as to obtain the flow of fluid in the bone under different injection angles, injection speeds and injection volumes. After the simulation, the fluid data including particle position, phase fraction, etc. are exported;

[0051] Step (9): The exported fluid data is subjected to fluid surface reconstruction and multiphase fluid rendering to obtain fluid animation.

[0052] Using Blender to perform bone modeling includes the following specific steps:

[0053] Step (1-1): Surface modeling of the bone shape and filling a certain volume;

[0054] Step (1-2): For the material inside the bone, according to the actual scene requirements, set porous materials with different porosities to represent healthy bone and osteoporotic bone

[0055] Based on smooth particle fluid dynamics, constructing a particle system for fluid simulation includes the following specific steps:

[0056] Step (2-1): Construct a smooth particle system in smooth particle fluid dynamics and configure relevant fluid properties, such as pressure, viscosity, acceleration, etc.

[0057] Step (2-2): Describe the motion of viscous incompressible fluid based on Navier-Stokes equations;

[0058] The unified fluid framework is constructed based on the polymer conformation tensor method, including the following specific steps:

[0059] Step (3-1): Introduce the polymer conformation tensor model and define a unified description framework for Newtonian fluids, shear-thinning fluids, and shear-thickening fluids;

[0060] Step (3-2): Calculating the viscoelastic stress of the fluid based on polymer conformation tensor theory;

[0061] Constructing a multiphase fluid system based on a mixture model includes the following specific steps:

[0062] Step (4-1): Introduce a mixture model, specifically an implicit mixture model, to build a multiphase fluid simulation framework;

[0063] Step (4-2): Based on the mixed model theory, calculate the dynamic properties of the multiphase fluid, including momentum and phase transport.

[0064] The visualization process of fluid data includes the following specific steps:

[0065] Step (5-1): Export simulation data, including particle positions and phase fraction files of the fluid;

[0066] Step (5-2): reconstructing the fluid surface of each frame according to the fluid particle data;

[0067] Step (5-3): Design rendering materials for the bone shape, bone interior, and fluid, render them into RGB images at different viewing angles, and create animations.

[0068] The superiority of the method of the present invention is compared with Figure 3 As shown, the results indicate that the method of the present invention is capable of stably mixing fluids with a wide range of viscosity ratios.

[0069] The present invention is based on the actual use of the sample simulation as shown in FIG. Figure 4 As shown, the fluidity difference of bone cement obtained with different modulation ratios will lead to different filling conditions. The horizontal axis is the timestamp, and each column represents the filling view at the same timestamp.

[0070] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0071] In the description of the present invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0072] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A non-Newtonian fluid simulation method for multiphase fluid, characterized in that: The following steps are involved: Modeling of bone structure, including bone shape modeling and porous material modeling inside the bone; Modeling of incompressible fluids based on smoothed particle fluid dynamics; Based on the polymer conformation tensor method, a unified modeling of Newtonian fluids, shear-thinning fluids, and shear-thickening fluids is performed to calculate the rheological properties of the fluids. In the process of calculating the rheological properties of fluids, a unified description framework for Newtonian fluids, shear-thinning fluids and shear-thickening fluids is defined by introducing the polymer conformation tensor model. Calculating the viscoelastic stress of the fluid based on polymer conformation tensor theory to obtain the rheological properties of the fluid; Based on the mixture model, a multiphase fluid simulation framework is constructed to support two-phase mixing modulation and multiphase fluid dynamics; In the process of building a multiphase fluid system based on a mixture model, a multiphase fluid simulation framework is constructed through the implicit mixture model Implicit MixtureModel; In the process of building a multiphase fluid simulation framework, the multiphase fluid is modeled based on the mixing model in multiphase fluid simulation, and the phase tensor model is strongly coupled with the phase volume fraction concept in the mixing model through the polymer concentration parameter; Export simulation data and reconstruct the fluid surface based on fluid particles. Use multiphase fluid rendering technology to render RGB images and create fluid animations.

2. The non-Newtonian fluid simulation method for multiphase fluid according to claim 1, characterized in that: In the process of modeling the bone structure, the surface of the bone shape is modeled and a certain volume is filled. For the material inside the bone, porous materials with different porosities are set according to the actual scene requirements to represent healthy bone and osteoporotic bone, thus completing the modeling of the bone structure.

3. The non-Newtonian fluid simulation method for multiphase fluid according to claim 2, characterized in that: In the process of modeling incompressible fluids, construct smooth particle systems in smooth particle fluid dynamics and configure relevant fluid properties; The motion of viscous incompressible fluid is described based on the Navier-Stokes equations, thereby completing the modeling of incompressible fluid.

4. The non-Newtonian fluid simulation method for multiphase fluid according to claim 1, characterized in that: In the process of constructing a unified description framework, a viscoelastic stress constitutive model related to the polymer phase tensor is established based on the polymer phase tensor model. The polymer phase tensor model is extended to describe shear-thinning non-Newtonian fluids, where nonlinear terms are introduced into the viscoelastic constitutive model to describe the nonlinear shear-related flow behavior. Extending the polymer conformational tensor model to describe shear-thickening non-Newtonian fluids involves converting the nonlinear conformational tensor model into a combination of a linear conformational tensor model and a non-Newtonian viscosity model, eliminating the nonlinear term and instead describing the nonlinear viscosity variation. A unified configuration is used to control the rheological range of the fluid, which is mainly divided into: Newtonian fluid range, shear thinning range and shear thickening range.

5. The non-Newtonian fluid simulation method for multiphase fluid according to claim 1, characterized in that: During the visualization process, simulation data is exported, including the particle position and phase fraction files of the fluid; Reconstruct the fluid surface of each frame based on the fluid particle data; Design rendering materials for bone shape, bone interior, and fluid, render them into RGB images at different perspectives, and create animations.

6. A non-Newtonian fluid simulation system for multiphase fluids, characterized in that: The system is used to implement a non-Newtonian fluid simulation method for multiphase fluids according to any one of claims 1 to 5, and the system includes: The first modeling module is used to model the bone structure, including bone shape modeling and porous material modeling inside the bone; The second modeling module is used to model incompressible fluid based on smoothed particle fluid dynamics; The first data processing module is used to uniformly model Newtonian fluids, shear-thinning fluids, and shear-thickening fluids based on the polymer conformation tensor method and calculate the rheological properties of the fluids; The second data processing module is used to build a multiphase fluid simulation framework based on the mixing model to support two-phase mixing modulation and multiphase fluid dynamics; The simulation module is used to export simulation data and reconstruct the fluid surface based on fluid particles, render RGB images using multiphase fluid rendering technology, and create fluid animations.

Images