A numerical simulation method and system for separating cells by a hydrocyclone

Abstract

The application provides a numerical simulation method and system for separating cells by using a hydrocyclone, and comprises the following steps: obtaining the concentration and surface area of cells to be separated, the number of fluid phases, and the shear stress of fluid under different shear rates; calculating the sphericity of the cells based on the surface area of the cells to be separated; obtaining the non-Newtonian fluid flow index of the fluid based on the shear stress of the fluid under different shear rates; calculating the drag force on the cells based on the sphericity of the cells and the non-Newtonian fluid flow index of the fluid; selecting different methods according to the concentration of the cells and the number of fluid phases, simulating the process of separating the cells by using a micro hydrocyclone based on the drag force, and obtaining characteristic parameters. The numerical simulation calculation is expanded from a single model to a plurality of models, which provides a guarantee for more comprehensive research and application of the micro hydrocyclone for separating cells.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of hydrocyclone, and particularly relates to a numerical simulation method and system for separating cells by using a hydrocyclone. BACKGROUND

[0002] The statements in this section merely provide background information related to the present application and do not necessarily constitute the prior art.

[0003] In the production processes of ethanol, monoclonal antibodies, microalgae and the like, continuous separation of yeast, microalgae, mammalian cells and the like needs to be achieved, and high-efficiency, low-cost, continuous and large-flux cell continuous separation technology and equipment need to be used. Although both the existing diaphragm and microfluidic technology can achieve a cell separation efficiency of more than 90%, the diaphragm is easy to be blocked and needs to be replaced regularly (15-30 days), which increases the risk of bacterial contamination and the cost of culture. The microfluidic technology has a small processing capacity (≤10 mL / min), which is difficult to meet the needs of large-scale production. Therefore, it is of great significance to develop a low-cost and large-processing-capacity cell separation and recovery equipment.

[0004] A micro hydrocyclone (cylinder diameter ≤ 50 mm) is a static device for efficiently separating fine particles (≥ 5 μm) in a centrifugal field by using the density and particle size difference of two-phase or multi-phase. In recent years, it has been used for effective separation of mammalian cells, yeast and microalgae. Because of its low cost, non-blocking and large processing capacity (1-10000 mL / min), it can overcome the defects of the existing diaphragm and microfluidic technology, and is considered to have great application potential in industrialized cell separation and recovery. The cost of using experimental research to separate cells by using a micro hydrocyclone is relatively high, and it is easy to be limited by experimental conditions. In contrast, the numerical simulation method has the characteristics of cost ratio and flexibility. At present, the main CFD-LPT (Computational Fluid Dynamics-Lagrangian Particle Tracking) model is used to study the separation of cells by using a micro hydrocyclone, and important characteristic parameters or distributions such as cell separation efficiency, water split ratio, velocity distribution and pressure distribution are obtained by simulation. Then, this numerical simulation method is single, and the scope of research is also limited. In addition, the existing numerical simulation model does not consider the shape characteristics of the cells and the non-Newtonian fluid characteristics of the cell culture solution, which affects the prediction of important characteristic parameters or distributions such as cell separation efficiency, water split ratio, velocity distribution and pressure distribution. SUMMARY

[0005] In order to solve the technical problems existing in the background art, the present application provides a numerical simulation method and system for separating cells by using a hydrocyclone, which expands from a single model to a numerical simulation calculation containing multiple models, and provides a guarantee for more comprehensive research and application of the separation of cells by using a micro hydrocyclone.

[0006] To achieve the above object, the present application adopts the following technical solutions:

[0007] The first aspect of the present application provides a numerical simulation method for separating cells by using a hydrocyclone, which comprises:

[0008] Obtaining the concentration and surface area of the cells to be separated, the number of fluid phases and the shear stress of the fluid under different shear rates;

[0009] Based on the surface area of the cells to be separated, the sphericity of the cells is calculated;

[0010] Based on the shear stress of the fluid under different shear rates, the non-Newtonian fluid flow index of the fluid is obtained;

[0011] Based on the sphericity of the cells and the non-Newtonian fluid flow index of the fluid, the drag force on the cells is calculated;

[0012] According to the concentration of the cells and the number of fluid phases, different methods are selected to simulate the process of separating the cells by using a micro hydrocyclone based on the drag force, and the characteristic parameters are obtained.

[0013] Further, if the cell concentration is less than or equal to the volume concentration, the method for simulating the process of separating the cells by using a micro hydrocyclone is:

[0014] Based on the fluid density in the hydrocyclone, the fluid pressure and fluid velocity of each calculation unit of the hydrocyclone are obtained, so as to obtain the pressure distribution and velocity distribution inside the hydrocyclone;

[0015] Based on the area of the inlet and outlet of the hydrocyclone, and combined with the velocity distribution inside the hydrocyclone, the water split ratio of the hydrocyclone is obtained;

[0016] After obtaining the mass of each cell, and combined with the drag force and pressure gradient force on each cell, the velocity of each cell is obtained, and the separation efficiency of the hydrocyclone on the cells is calculated.

[0017] Further, if the cell concentration is greater than the volume concentration, and the number of fluid phases is less than a set value, the Stokes number of the cells is compared with a threshold value.

[0018] Further, if the Stokes number of the cells is less than the threshold value, the method for simulating the process of separating the cells by using a micro hydrocyclone is:

[0019] Based on the velocity, density, viscosity and volume fraction of each phase in each calculation unit of the hydrocyclone, combined with the drag force and pressure gradient force on each phase, the mixed phase pressure and mixed phase velocity of each calculation unit of the hydrocyclone are obtained, so as to obtain the pressure distribution and velocity distribution inside the hydrocyclone;

[0020] Based on the area of the inlet and outlet of the cyclone, combined with the velocity distribution of each phase inside the cyclone, the water split ratio and the cell separation efficiency of the cyclone are obtained.

[0021] Further, if the Stokes number of the cell is greater than or equal to a threshold value, the method for simulating the process of separating cells by the micro hydrocyclone is:

[0022] Based on the volume fraction, density and velocity of each phase in each calculation unit of the cyclone, combined with the drag force and pressure gradient force received by each phase, the velocity and pressure of each phase in each calculation unit of the cyclone are obtained, so as to obtain the pressure distribution and velocity distribution inside the cyclone;

[0023] Based on the area of the inlet and outlet of the cyclone, combined with the velocity distribution of each phase inside the cyclone, the water split ratio and the cell separation efficiency of the cyclone are obtained.

[0024] Further, if the cell concentration is greater than the volume concentration, and the number of fluid phases is greater than or equal to a set value, the method for simulating the process of separating cells by the micro hydrocyclone is:

[0025] Based on the fluid density in each calculation unit of the cyclone, combined with the drag force and pressure gradient force received by each cell, the fluid pressure and fluid velocity of each calculation unit are obtained, so as to obtain the pressure distribution and velocity distribution inside the cyclone;

[0026] Based on the area of the inlet and outlet of the cyclone, combined with the velocity distribution inside the cyclone, the water split ratio of the cyclone is obtained;

[0027] Based on the radius, mass, relative tangential and normal velocity between cells and the overlap amount generated by collision, the contact force and damping force generated by the collision between cells are calculated;

[0028] After obtaining the velocity of the cell based on the contact force and damping force, the separation rate of the cyclone to the cell is calculated.

[0029] The second aspect of the present application provides a numerical simulation system for separating cells by a hydrocyclone, which comprises:

[0030] The data acquisition module is configured to acquire the concentration and surface area of the cells to be separated, the number of fluid phases and the shear stress of the fluid under different shear rates;

[0031] The sphericity calculation module is configured to calculate the sphericity of the cell based on the surface area of the cell to be separated;

[0032] The non-Newtonian fluid flow index calculation module is configured to obtain the non-Newtonian fluid flow index of the fluid based on the shear stress of the fluid under different shear rates;

[0033] a drag force calculation module configured to calculate the drag force received by the cells based on the sphericity of the cells and the non-Newtonian fluid flow index of the fluid;

[0034] a simulation module configured to simulate the process of separating the cells by the micro hydrocyclone based on the drag force according to the cell concentration and the number of fluid phases to obtain the characteristic parameters.

[0035] Further, if the cell concentration is greater than the volume concentration and the number of fluid phases is less than a set value, the Stokes number of the cells is compared with a threshold value.

[0036] A third aspect of the present application provides a computer readable storage medium having a computer program stored thereon, the program being executed by a processor to implement the steps of the numerical simulation method for separating cells by a hydrocyclone.

[0037] A fourth aspect of the present application provides a computer device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, the processor implementing the steps of the numerical simulation method for separating cells by a hydrocyclone when executing the program.

[0038] Compared with the prior art, the present application has the following beneficial effects:

[0039] The present application provides a numerical simulation method for separating cells by a hydrocyclone, which clearly defines the applicable conditions of the CFD-LPT, CFD-DEM and TFM models in the numerical simulation of separating cells by a micro hydrocyclone, forms a complete numerical simulation method, and expands the existing numerical simulation method for separating cells by a micro hydrocyclone from a single CFD-LPT model to a numerical simulation calculation containing three models (CFD-LPT, CFD-DEM and TFM), thereby providing a guarantee for more comprehensive research and application of separating cells by a micro hydrocyclone.

[0040] The present application provides a numerical simulation method for separating cells by a hydrocyclone, which modifies the existing CFD-LPT model by considering the shape characteristics of the cells and the non-Newtonian fluid characteristics of the cell culture solution, and proposes a numerical simulation for separating cells by a micro hydrocyclone based on the CFD-DEM (Computational Fluid Dynamics-Discrete Element Method) and TFM (Two Fluids Model) models, to obtain important characteristic parameters or distributions such as the separation efficiency of the cells, the water split ratio, the velocity distribution and the pressure distribution.

[0041] The application provides a numerical simulation method for separating cells by using a hydrocyclone, which considers the shape characteristics of the cells and the non-Newtonian fluid characteristics of the cell culture solution according to the actual conditions of the cells and the cell culture solution, and provides a method guarantee for more comprehensive research and application of the micro hydrocyclone for separating cells.

[0042] The application provides a numerical simulation method for separating cells by using a hydrocyclone, which considers the shape characteristics of the cells and the non-Newtonian fluid characteristics of the cell culture solution according to the actual conditions of the cells and the cell culture solution, and provides a method guarantee for more comprehensive research and application of the micro hydrocyclone for separating cells. BRIEF DESCRIPTION OF DRAWINGS

[0043] The drawings constituting a part of the specification of the application are used to provide further understanding of the application, the schematic embodiments of the application and the description thereof are used to explain the application, and do not constitute improper limitation on the application.

[0044] Figure 1 The application provides a numerical simulation method for separating cells by using a hydrocyclone, which considers the shape characteristics of the cells and the non-Newtonian fluid characteristics of the cell culture solution according to the actual conditions of the cells and the cell culture solution, and provides a method guarantee for more comprehensive research and application of the micro hydrocyclone for separating cells. DETAILED DESCRIPTION

[0045] The application will be further described below in combination with the drawings and embodiments.

[0046] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the application belongs.

[0047] It should be noted that the terms used herein are only for the purpose of describing specific embodiments, and are not intended to limit the exemplary embodiments according to the application. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form, and in addition, it should be understood that when the terms "comprise" and / or "include" are used in the specification, they indicate the presence of the features, steps, operations, devices, components and / or combinations thereof.

[0048] Embodiment one

[0049] The embodiment provides a numerical simulation method for separating cells by using a hydrocyclone, which considers the shape characteristics of the cells and the non-Newtonian fluid characteristics of the cell culture solution according to the actual conditions of the cells and the cell culture solution, and provides a method guarantee for more comprehensive research and application of the micro hydrocyclone for separating cells. Figure 1As shown, the concentration and surface area of the cells to be separated, the number of fluid phases and the shear stress of the fluid under different shear rates are obtained; the sphericity of the cells is calculated based on the surface area of the cells to be separated; the non-Newtonian fluid flow index of the fluid is obtained based on the shear stress of the fluid under different shear rates; the drag force on the cells is calculated based on the sphericity of the cells and the non-Newtonian fluid flow index of the fluid; and different methods are selected according to the concentration of the cells and the number of fluid phases, and the process of separating the cells by the micro hydrocyclone is simulated based on the drag force to obtain characteristic parameters (the characteristic parameters include: separation efficiency, water split ratio, velocity distribution and pressure distribution, or separation efficiency, water split ratio, velocity distribution, pressure distribution and particle-particle interaction force). Specifically, the process includes the following steps:

[0050] Step 1: Obtain the cell concentration VOL and the number of fluid (cell culture solution) phases.

[0051] Specifically, the cell concentration is obtained by using a cell counting plate.

[0052] Step 2: Select a numerical simulation model according to the cell concentration and the number of fluid phases.

[0053] The numerical simulation model includes a CFD-LPT model (first numerical simulation model), a TFM model (second numerical simulation model) and a CFD-DEM model (third numerical simulation model).

[0054] Specifically, when the cell concentration is less than or equal to the volume concentration 4%, the CFD-LPT model is selected; otherwise, the TFM model or the CFD-DEM model is selected; when the number of fluid phases (one cell particle is regarded as one phase of the fluid) is greater than or equal to a set value 20, the CFD-DEM model is selected considering the calculation stability; otherwise, the TFM model is selected.

[0055] Step 3: Obtain the surface area of the cells, calculate the sphericity of the cells based on the surface area of the cells; obtain the shear stress of the cell culture solution under different shear rates, and obtain the non-Newtonian fluid flow index of the cell culture solution; calculate the drag force and the pressure gradient force based on the sphericity of the cells and the non-Newtonian fluid flow index of the cell culture solution.

[0056] Since the cells can exhibit non-spherical characteristics, the sphericity φ is used to represent the shape characteristics of the cells in the present application, and the sphericity is defined as the ratio of the surface area S s of a spherical particle to the surface area S non of a non-spherical particle with the same volume. The surface area S non of the cells can be measured by a particle size analyzer or the like instrument to calculate the sphericity φ of the cells, and the formula of the sphericity is as follows:

[0057]

[0058] where S s is the surface area of a spherical particle of the same volume as the cell.

[0059] Since the cell culture fluid can exhibit non-Newtonian fluid characteristics in some cases, the present application intends to use the widely used power-law rheological model to characterize the non-Newtonian fluid characteristics of the cell culture fluid. By fitting the rheological curve of the shear stress of the cell culture fluid at different shear rates, the non-Newtonian fluid flow index of the cell culture fluid is obtained. The calculation formula of the shear stress is as follows:

[0060] τ s = Kγ n (2)

[0061] where τ s , K, γ, n are the shear stress, viscosity coefficient, shear rate, and flow index of the cell culture fluid, respectively; the value of K is a measure of viscosity, and the higher the viscosity, the larger the value of K; the value of n is a measure of non-Newtonian, indicating the degree of deviation of the fluid from Newtonian fluid, and the value of pseudoplastic fluid is greater than 1, and the value of dilatant fluid is less than 1; by setting different values of γ, the value of τs is obtained by the viscometer, and the value of n is obtained by drawing the rheological curve.

[0062] The drag coefficient C D and the coefficient β are corrected by the sphericity φ of formula (1) and the flow index n of formula (2), so as to correct the drag force model (formula (3)) to obtain the drag force (drag force) of the particle I (single cell):

[0063]

[0064] where πd I 2 / 4 is the volume of the particle I, ρ f is the density of the cell culture fluid (fluid), ε is the porosity, d I is the observed diameter of the particle I; C D is the drag coefficient, which is related to the Reynolds number Re, the sphericity φ, and the non-Newtonian fluid flow index n; U s is the relative velocity between the particle and the fluid; β is the coefficient, which is related to the Reynolds number Re and the non-Newtonian fluid flow index n, and the formula is as follows:

[0065]

[0066] The formula of the pressure gradient (pg) force of the particle I is as follows:

[0067]

[0068] where V p,I is the volume of the particle I, is the pressure gradient.

[0069] Step 4, based on the modified drag force and the selected numerical simulation model, simulate the separation process of the micro hydrocyclone for cells to obtain the separation efficiency, water split ratio, velocity distribution and pressure distribution, or the force between particles and particles.

[0070] (1) If the selected numerical simulation model is the CFD-LPT model, the process of simulating the separation process of the micro hydrocyclone for cells by the CFD-LPT model is: based on the fluid density in the hydrocyclone, the fluid pressure and fluid velocity of each calculation unit of the hydrocyclone are obtained by solving the control equation, so as to obtain the pressure distribution and velocity distribution inside the hydrocyclone; based on the area of the inlet and outlet of the hydrocyclone, combined with the velocity distribution inside the hydrocyclone, the water split ratio of the hydrocyclone is obtained; the mass of each cell is obtained, combined with the drag force and pressure gradient force received by each cell, the velocity of each cell is obtained, combined with the position of each cell, the number of cells at the inlet and outlet of the hydrocyclone is counted, and the separation efficiency of the hydrocyclone for cells can be obtained.

[0071]

[0072] wherein En is the separation efficiency obtained according to the number of cells, N 出口 and N 入口 are the number of cells at the outlet and the inlet, respectively. The position of the calculation unit is known, and the position of the cell is determined according to the position of the calculation unit.

[0073] The control equation for fluid calculation is as follows:

[0074]

[0075]

[0076] In the formula, t is time, i and j represent i direction and j direction, μ is fluid viscosity, ρ f is fluid density (cell culture solution density), u is fluid velocity, u i and u j are the velocity component vectors of the fluid velocity u in the i direction and the j direction, respectively, u' is the fluctuating velocity, u' i are the velocity component vectors of the fluctuating velocity in the i direction and the j direction, respectively, is the Reynolds stress term, and p is the pressure; the second term on the left side of formula (7) is the convection term, and the first term on the right side represents the pressure gradient, and the second term is the diffusion term.

[0077] ① Set the boundary conditions of the hydrocyclone, obtain the density and fluctuation velocity of the cell culture liquid of each calculation unit of the hydrocyclone, and solve the control equations (equations (6) and (7)) to obtain the fluid pressure and fluid velocity of each calculation unit (select several cross sections of the hydrocyclone from the top to the bottom end, and select several points in the near-wall area of each cross section, and each point corresponds to a calculation unit) of the calculation domain of the hydrocyclone, so as to obtain the pressure distribution (i.e. the value of p in each calculation unit) and velocity distribution (i.e. the value of u in each calculation unit) inside the hydrocyclone.

[0078] ② Obtain the areas of the inlet and outlet of the hydrocyclone, and combine the velocity distribution inside the hydrocyclone (the velocity u of equations (6) and (7), i.e. the velocity of all calculation units at the inlet and outlet), to calculate the volumetric flow rate of the inlet and outlet of the hydrocyclone (the flow rate of each calculation unit at the inlet and outlet is added to obtain), so as to calculate the water diversion ratio of the hydrocyclone. The calculation of the flow field in this step also lays the foundation for the calculation of the cell separation efficiency (equation (8)).

[0079] ③ Obtain the mass of each cell, combine the drag force and pressure gradient force received by each cell, and through equation (8), the velocity of each cell particle I can be obtained, combined with the position of each cell particle I, and then the number of cells at the inlet and outlet of the hydrocyclone is obtained, so as to obtain the separation efficiency of the hydrocyclone to the cell particles according to equation (5).

[0080] The fluid pressure and velocity obtained through equations (6) and (7) can be used to calculate the force of the fluid on the particle, so as to calculate the movement speed v I of a cell particle I.

[0081]

[0082] Wherein, f p-f,I is the force of the fluid on the particle (including the drag force f d,I shown in equation (3) and the pressure gradient force f pg,I shown in equation (4), i.e. f p-f,I =f d,I +f pg,I ); m I is the mass of the particle I, and g is the acceleration of gravity.

[0083] (2) The TFM model calculates the cells as fluid, including two specific models: mixture model and Eulerian-Eulerian model. When the Stokes number of the cells is less than the threshold value 1, the mixture model is adopted; when the Stokes number of the cells is greater than 1, the mixture model is no longer applicable, and the Eulerian-Eulerian model is adopted.

[0084] (201)If the selected numerical simulation model is the mixture model, the process of simulating the separation of cells by the micro hydrocyclone using the mixture model is as follows: based on the velocity, density, viscosity and volume fraction of each phase in each calculation unit of the cyclone, the drift velocity, mass average velocity, mixture density and mixture viscosity are obtained from the formula (12)-(16) combined with the drag force and pressure gradient force received by each phase, and then the mixed phase pressure and mixed phase velocity of each calculation unit of the cyclone are obtained from the formula (10) and (11), so as to obtain the pressure distribution and velocity distribution inside the cyclone; for the TFM model (including the mixture model and the Euler-Euler model), the number of cell particles cannot be tracked, so the cell separation efficiency cannot be calculated according to the formula (5). For the TFM model, another method for calculating the cell separation efficiency is adopted, that is, the cell separation efficiency and the water separation ratio are determined according to the volume flow rate of each phase (including water and cells) at the inlet and outlet, as shown in the formula (9). The volume flow rate is calculated according to the area of the inlet and outlet of the cyclone and the velocity distribution of each phase inside the cyclone.

[0085]

[0086] Eq is the separation efficiency obtained according to the cell volume flow rate, V 出口 and V 入口 are the volume flow rates at the outlet and the inlet, respectively, A 出口 and A 入口 are the areas at the outlet and the inlet, respectively.

[0087] For the mixture model, the cell particles are calculated as a phase of fluid. The pressure p and the velocity u m of each calculation unit in the calculation domain of the cyclone can be obtained by solving the formula (10) and (11), so as to obtain the pressure distribution (i.e. the numerical value of the pressure in each calculation unit) and the velocity distribution (i.e. the numerical value of the velocity in each calculation unit) inside the cyclone. According to the area of the inlet and outlet and the velocity of the formula (10) and (11), the volume flow rate of each phase at the inlet and outlet can be calculated, so as to calculate the water separation ratio and the cell separation efficiency (see the formula (9)).

[0088]

[0089]

[0090] wherein g is the acceleration of gravity, is the pressure gradient in the i direction, that is, the is the Reynolds stress described by the RSM model, P s,total is the sum of the pressures P s,k of all solid phases (particle phases), and u dr,kiuikis the component of the drift velocity of the kth phase in the i direction; u dr,kj uikis the component of the drift velocity of the kth phase in the j direction; in equations (10), (11), the mass average (mixture phase) velocity is u m , the velocity components of the mass average velocity in the i and j directions are u mi and u mj ; u mi , the mixture (mixture phase) density is p m , and the mixture viscosity is m m , which can be automatically calculated, are given by the following equations, respectively:

[0091]

[0092]

[0093]

[0094] where k represents different phases; u k is the velocity of the kth phase; u ki , p k , m k are the velocity component in the i direction, the density and the viscosity of the kth phase, respectively, which are set before the calculation begins; n k k is the total number of phases, a dr,ki is the volume fraction of the kth phase, which is also set before the calculation begins. The above k phases satisfy the continuity equation:

[0095]

[0096] where the calculation formula of the drift velocity u k1,i is as follows:

[0097]

[0098] where u k1,i is the component of the relative velocity of the kth phase to the primary phase water in the i direction, which is calculated according to the drag force received by the kth phase (including cells). The mass average velocity, the mixture density, the mixture viscosity and the drift velocity are obtained from equations (12)-(16), which are further calculated to obtain the velocity distribution, the pressure distribution, the water flow ratio and the cell separation efficiency after being brought into equations (10), (11).

[0099] (202)If the Stokes number of the cells is greater than or equal to the threshold value, the process of separating the cells by the micro hydrocyclone is simulated by using the Euler-Euler model, and the method for simulating the process of separating the cells by the micro hydrocyclone is as follows: the volume fraction, density and velocity of each phase in each calculation unit of the hydrocyclone are obtained, the drag force and the pressure gradient force borne by each phase are combined, formula (17) and (18) are solved, and thus the pressure distribution and the velocity distribution inside the hydrocyclone are obtained; the areas of the inlet and the outlet of the hydrocyclone are obtained, the velocity distribution of each phase (including water and cells) inside the hydrocyclone is combined, and the water split ratio of the hydrocyclone and the separation efficiency of the cells (see formula (9)) are obtained.

[0100] The Euler-Euler model also regards the particles as fluids. Since the model solves equations for each phase, the model has higher accuracy. The pressure and the velocity of each calculation unit in the calculation domain of the hydrocyclone are obtained by solving formula (17) and (18), and thus the pressure distribution and the velocity distribution inside the hydrocyclone are obtained. According to the areas of the inlet and the outlet and the velocity of each phase in formula (17) and (18), the volume flow rates of each phase at the inlet and the outlet are calculated, and thus the water split ratio and the separation efficiency of the cells are calculated.

[0101]

[0102]

[0103] wherein k represents different phases; α k , ρ k , u k are the volume fraction, the density and the velocity of the k phase, which are set in the calculation software Fluent; is the pressure gradient, and the pressure gradient force is calculated according to formula (4); P s,k is the solid pressure of the k phase, is the stress-strain tensor of the k phase, F D is the drag force borne by the k phase (its calculation formula is the same as that of f d,I , only the sign is slightly different), which is automatically calculated in the calculation process.

[0104] For the TFM model, formula (1) and (2) are also used to consider the shape characteristics of the cells and the non-Newtonian fluid characteristics of the cell culture solution respectively, so as to correct the drag force model (formula (3)), and thus the influences of the sphericity φ and the flow index n on the velocity distribution, the pressure distribution, the water split ratio and the separation efficiency of the cells (formula (17-18)) inside the hydrocyclone are considered.

[0105] (3) If the cell concentration is greater than the volume concentration and the number of fluid phases is greater than or equal to a set value, the CFD-DEM model is used to simulate the process of separating cells by the micro hydrocyclone. The method for simulating the process of separating cells by the micro hydrocyclone is as follows: based on the fluid density in each calculation unit of the hydrocyclone, the drag force and the pressure gradient force borne by each cell are combined, the fluid pressure and the fluid velocity of each calculation unit are obtained through formulas (19) and (20), and thus the pressure distribution and the velocity distribution inside the hydrocyclone are obtained; based on the area of the inlet and the outlet of the hydrocyclone, the velocity distribution inside the hydrocyclone is combined, and the water split ratio of the hydrocyclone is obtained; based on the radius, the mass of the cells, the relative tangential and normal velocities between the cells, and the overlap amount generated by the collision, the contact force and the damping force generated by the collision between the cells are calculated through formulas (23-26); based on the contact force and the damping force, the velocity of each cell is obtained through formulas (21) and (22), the number of cells at the inlet and the outlet of the hydrocyclone is counted in combination with the position of the cells, and the separation efficiency of the hydrocyclone for the cells can be obtained according to formula (5).

[0106] Compared with the CFD-LPT model, the CFD-DEM model can consider the collision force between the cells in the micro hydrocyclone and the interaction between the fluid and the cells in a bidirectional coupling manner. On the one hand, the boundary conditions of the hydrocyclone are set, and the boundary conditions and the motion information (such as the velocity and the force borne) of the cell particles obtained through formulas (21-22) are input into formulas (19-20), the pressure and the velocity of the fluid in each calculation unit in the calculation domain of the hydrocyclone are obtained by solving formulas (19) and (20), and thus the pressure distribution and the velocity distribution inside the hydrocyclone are obtained. According to the area of the inlet and the outlet and the fluid velocity of formulas (19) and (20), the volume flow rate of the inlet and the outlet fluid can be calculated, and thus the water split ratio is calculated. On the other hand, the fluid information is obtained through this step of calculation, and thus the motion velocity of the cells (formulas (21-22)) is calculated.

[0107]

[0108]

[0109] wherein ε, u, u', t, p f , P, F p-f , τ, g, are the porosity, the fluid velocity, the fluctuation velocity, the time, the fluid density, the pressure, the volume-averaged cell-fluid interaction force, the viscous stress tensor, the gravitational acceleration, and the Reynolds stress, respectively. Among them, the fluid density and the gravitational acceleration are set before the calculation starts. The other parameters are obtained through calculation after the boundary conditions of the hydrocyclone are set. f p-f,Iis the inter-particle force acting on cell particle I in the computational unit, including the drag force f d,I and the pressure gradient force f pg,I ( formula ( 4 ) ).

[0110] In the DEM calculation, the translation and rotation of the cell particle are considered simultaneously, and are calculated by formula (21) and formula (22), respectively. According to the area of the inlet and outlet and the velocity of formula (21) and (22), the volume flow rate of the cell particle at the inlet and outlet can be calculated, and thus the separation efficiency of the cell can be calculated:

[0111]

[0112]

[0113] wherein m I , I I , ω I , V I are the mass, moment of inertia, rotational velocity, translational velocity of particle I, respectively, which are automatically obtained in the calculation process; f c,IJ and f d,IJ are the contact force and damping force generated by the collision of cell particles i and j, respectively, including normal and tangential forces, and the specific calculation is shown in formula (23-26); formula (22) calculates the rotation of the cell particle, T c,IJ and T r,IJ are the sliding torque and rolling torque between cell particles I and J, which are calculated according to f c,IJ and f d,IJ .

[0114] The normal contact force generated by the collision between cells is:

[0115]

[0116] The normal damping force generated by the collision between cells is:

[0117]

[0118] The tangential contact force generated by the collision between cells is:

[0119]

[0120] The tangential damping force generated by the collision between cells is:

[0121]

[0122] In formula (23-26), the parameters required for calculating the collision force are the parameters involved in the right side of the formula; wherein E is the Young's modulus, R Iis the radius of the cell particle, δ is the overlap amount generated by the collision between the cell particles, v t,IJ , v n,IJ are the relative tangential and normal velocities of cells I and J, m I is the mass of the cell particle, c is a coefficient, v is the Poisson's ratio, μ s is the sliding friction coefficient; δ, v t,IJ , v n,IJ is automatically obtained in the calculation process, and other parameters are set before the calculation begins.

[0123] For the CFD-DEM method, the shape characteristics of the cells and the non-Newtonian fluid characteristics of the cell culture solution are also considered by using formula (1-2) respectively, so as to correct the drag force model (formula (3)), and then the influence of the sphericity φ and the flow index n on the velocity distribution, the pressure distribution, the water flow ratio, and the cell separation efficiency (formula (19-22)) in the internal part of the cyclone is considered.

[0124] By determining the applicable conditions of the CFD-LPT, CFD-DEM and TFM models in the numerical simulation of the separation of cells in the micro hydrocyclone, a complete numerical simulation method is formed, the existing numerical simulation method of the separation of cells in the micro hydrocyclone is expanded from a single CFD-LPT model to a numerical simulation calculation containing three models (CFD-LPT, CFD-DEM and TFM), and the guarantee for more comprehensive research and application of the micro hydrocyclone for separating cells is provided.

[0125] Embodiment Two

[0126] The embodiment provides a numerical simulation system for separating cells by using a hydrocyclone, and specifically comprises the following modules:

[0127] The data acquisition module is configured to acquire the concentration and surface area of the cells to be separated, the number of fluid phases, and the shear stress of the fluid under different shear rates.

[0128] The sphericity calculation module is configured to calculate the sphericity of the cells based on the surface area of the cells to be separated.

[0129] The non-Newtonian fluid flow index calculation module is configured to obtain the non-Newtonian fluid flow index of the fluid based on the shear stress of the fluid under different shear rates.

[0130] The drag force calculation module is configured to calculate the drag force received by the cells based on the sphericity of the cells and the non-Newtonian fluid flow index of the fluid.

[0131] The simulation module is configured to select different methods based on the concentration of the cells and the number of fluid phases, simulate the process of separating cells by using the micro hydrocyclone based on the drag force, and obtain characteristic parameters.

[0132] wherein if the cell concentration is greater than the volume concentration and the number of fluid phases is less than a set value, then the cell's Stokes number is compared to a threshold value.

[0133] It should be noted that each module in the embodiment corresponds to each step in the first embodiment, and the specific implementation process is the same, which will not be repeated here.

[0134] Embodiment three

[0135] The embodiment provides a computer readable storage medium, which stores a computer program, and the program is executed by a processor to realize the steps in the numerical simulation method for separating cells by using a hydrocyclone according to the first embodiment.

[0136] Embodiment four

[0137] The embodiment provides a computer device, which comprises a memory, a processor, and a computer program stored in the memory and capable of running on the processor, and the processor realizes the steps in the numerical simulation method for separating cells by using a hydrocyclone according to the first embodiment when executing the program.

[0138] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can adopt a hardware embodiment, a software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer usable storage media (including but not limited to disk storage and optical storage) containing computer usable program codes.

[0139] The present application is described with reference to flowcharts and / or block diagrams of the method, device (system), and computer program product according to the embodiments of the present application. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, and the combination of the flows and / or blocks in the flowcharts and / or block diagrams can be realized by computer program instructions. These computer program instructions can be provided to a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to produce a machine, so that the instructions executed by the computer or other programmable data processing devices produce a device that implements the functions specified in the flowcharts and / or block diagrams. Figure 1 The function of one flow or multiple flows and / or blocks Figure 1 The function of one flow or multiple flows and / or blocks

[0140] These computer program instructions can also be stored in a computer readable storage medium, which can guide the computer or other programmable data processing devices to work in a specific way, so that the instructions stored in the computer readable storage medium produce a product including instruction devices, which realize the functions specified in the flowcharts and / or block diagrams.Figure 1 one or more processes and / or functions specified in the block or blocks. Figure 1

[0141] These computer program instructions can also be loaded into a computer or other programmable data processing device, so that a series of operational steps are performed on the computer or other programmable data processing device to generate a computer-implemented process, so that the instructions executed on the computer or other programmable data processing device provide steps for implementing the functions specified in the flowchart Figure 1 one or more processes and / or functions specified in the block or blocks. Figure 1

[0142] Those of ordinary skill in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by computer programs instructing related hardware, and the programs can be stored in a computer-readable storage medium. When the programs are executed, they can include the processes of the above-mentioned embodiment methods. The storage medium can be a magnetic disc, an optical disc, a read-only memory (ROM), a random access memory (RAM), or the like.

[0143] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Those of ordinary skill in the art can make various modifications and changes to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.​​

Claims

1. A numerical simulation method for separating cells using a hydrocyclone, characterized in that, include: Obtain the concentration and surface area of ​​the cells to be separated, the number of fluid phases, and the shear stress of the fluid at different shear rates; Calculate the sphericity of the cells based on their surface area. The non-Newtonian fluid flow index of the fluid is obtained based on the shear stress of the fluid at different shear rates. The drag force on the cell is calculated based on the sphericity of the cell and the non-Newtonian fluid flow index. Based on cell concentration and fluid phase number, different methods were selected to simulate the cell separation process of the micro hydrocyclone based on the drag force, and characteristic parameters were obtained.

2. The numerical simulation method for separating cells using a hydrocyclone as described in claim 1, characterized in that, If the cell concentration is less than or equal to the volume concentration, the method for simulating the cell separation process using a micro hydrocyclone is as follows: Based on the fluid density inside the hydrocyclone, the fluid pressure and fluid velocity of each computational unit of the hydrocyclone are obtained, thereby obtaining the pressure distribution and velocity distribution inside the hydrocyclone. Based on the area of ​​the hydrocyclone inlet and outlet, and combined with the velocity distribution inside the hydrocyclone, the water flow ratio of the hydrocyclone is obtained. After obtaining the mass of each cell and combining the drag force and pressure gradient force acting on each cell to determine the velocity and position of each cell, the separation efficiency of the hydrocyclone for the cells is calculated.

3. The numerical simulation method for separating cells using a hydrocyclone as described in claim 1, characterized in that, If the cell concentration is greater than the volume concentration and the number of fluid phases is less than a set value, then the Stokes number of the cells is compared with a threshold.

4. The numerical simulation method for separating cells using a hydrocyclone as described in claim 3, characterized in that, If the Stokes number of the cells is less than a threshold, the method for simulating the cell separation process using a micro hydrocyclone is as follows: Based on the velocity, density, viscosity and volume fraction of each phase in each calculation unit of the hydrocyclone, combined with the drag force and pressure gradient force on each phase, the mixed phase pressure and mixed phase velocity of each calculation unit of the hydrocyclone are obtained, thus obtaining the pressure distribution and velocity distribution inside the hydrocyclone. Based on the area of ​​the hydrocyclone inlet and outlet, combined with the velocity distribution of each phase inside the hydrocyclone, the water flow ratio and cell separation efficiency of the hydrocyclone are obtained.

5. The numerical simulation method for separating cells using a hydrocyclone as described in claim 3, characterized in that, If the Stokes number of the cells is greater than or equal to the threshold, the method for simulating the cell separation process using a micro hydrocyclone is as follows: Based on the volume fraction, density, and velocity of each phase in each computational unit of the hydrocyclone, combined with the drag force and pressure gradient force on each phase, the velocity and pressure in each computational unit of the hydrocyclone are obtained, thus obtaining the pressure distribution and velocity distribution inside the hydrocyclone. Based on the area of ​​the hydrocyclone inlet and outlet, combined with the velocity distribution of each phase inside the hydrocyclone, the water flow ratio and cell separation efficiency of the hydrocyclone are obtained.

6. The numerical simulation method for separating cells using a hydrocyclone as described in claim 1, characterized in that, If the cell concentration is greater than the volume concentration and the fluid phase number is greater than or equal to a set value, then the method for simulating the cell separation process in a micro hydrocyclone is as follows: Based on the fluid density in each computational unit of the hydrocyclone, combined with the drag force and pressure gradient force on each cell, the fluid pressure and fluid velocity of each computational unit are obtained, thus obtaining the pressure distribution and velocity distribution inside the hydrocyclone. Based on the area of ​​the hydrocyclone inlet and outlet, and combined with the velocity distribution inside the hydrocyclone, the water flow ratio of the hydrocyclone is obtained. Based on the cell's radius, mass, relative tangential and normal velocities between cells, and the amount of overlap caused by the collision, the contact force and damping force generated by the inter-cell collision are calculated. Based on the contact force and damping force, after obtaining the cell velocity, the separation rate of the cells by the hydrocyclone is calculated.

7. A numerical simulation system for separating cells using a hydrocyclone, characterized in that, include: The data acquisition module is configured to acquire the concentration and surface area of ​​the cells to be separated, the fluid phase number, and the shear stress of the fluid at different shear rates. The sphericity calculation module is configured to calculate the sphericity of the cells based on the surface area of ​​the cells to be separated. The non-Newtonian fluid flow index calculation module is configured to obtain the non-Newtonian fluid flow index of the fluid based on the shear stress of the fluid at different shear rates. The drag force calculation module is configured to calculate the drag force on the cell based on the sphericity of the cell and the non-Newtonian fluid flow index of the fluid. The simulation module is configured to: select different methods based on the cell concentration and fluid phase number to simulate the cell separation process of the micro hydrocyclone based on the drag force, and obtain characteristic parameters.

8. The numerical simulation system for separating cells using a hydrocyclone as described in claim 7, characterized in that, If the cell concentration is greater than the volume concentration and the number of fluid phases is less than a set value, then the Stokes number of the cells is compared with a threshold.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the steps in the numerical simulation method for separating cells in a hydrocyclone as described in any one of claims 1-6.

10. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the steps in the numerical simulation method for separating cells using a hydrocyclone as described in any one of claims 1-6.

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