146 results about "Continuity equation" patented technology

The invention belongs to the technical field of unconventional oil gas production increasing transformation and particularly, relates to a shale gas horizontal well refracturing productivity calculation method. The method comprises the following steps of: by using a shale reservoir as an elastic material which is small in deformation, establishing a stress-strain model and a reservoir physical property parameter dynamic model; establishing a continuity equation in kerogen and an inorganic substance; respectively carrying out numerical solution on an established solid deformation control equation and shale gas multiscale seepage equation; bringing geological parameters, physical property parameters and primary fracturing design parameters of a shale gas well reservoir into a shale gas fluid-solid coupling numerical model, and recording a pressure field and hydraulic fracture flow conductivity of the reservoir; and bringing refracturing design parameters into the shale gas fluid-solid coupling numerical model, and calculating productivity of a shale gas well after refracturing. According to the method disclosed by the invention, seepage characteristics and stress-pressure field dynamic variations of the shale reservoir are considered, productivity and a recovery ratio of the shale reservoir after refracturing are predicted, and shale gas horizontal well refracturing optimizationdesign is guided.

An electronic device simulator includes a three-dimensional lumped device model, a three-dimensional visco-elastic process simulation model and a material design model that are interlinked with each other. The three-dimensional lumped device element model comprises a Poisson's equation model, an electron continuity equation model, a hole continuity equation model, a Maxwell's equations model, an eddy current equation model, and an Ohm's law equation model. The simulator accounts for the three dimensional characteristics of the circuit to determine circuit performance.

The present disclosure provides a numerical simulation method for obtaining a flow field of an incompressible flow. The method comprises the steps: reading computational mesh information of a simulation object, physical property parameters of a fluid working medium and flow initial boundary value condition information, and calculating mesh parameters and time step parameters; initializing the velocity field and the pressure field; using m-step explicit Runge-Kutta to solve the momentum equation of incompressible fluid to obtain the virtual velocity field of the simulated object, where m represents the number of steps used and m>=2; based on the virtual velocity field and the read parameters and information, deducing the pressure equation from the continuity equation, and determining the next pressure by the pressure equation; when the last step of the m-step explicit Runge-Kutta is carried out, correcting the velocity field by the obtained pressure, and obtaining the next velocity; using the convergence criterion to judge whether the numerical solution is convergent or not, and if so, outputting the flow field data information, and if it is not convergent, repeating the iterative process until the numerical solution converges.

The invention provides a GaAs solar energy cell performance degeneration prediction method in a space environment. The method comprises the following four steps: (1) establishment of a one-dimensional model of a GaAs solar energy cell in the space environment; (2) consideration of space particle radiation damage on an effective life of a carrier; (3) calculation of GaAs solar cell temperature; (4) realization of GaAs solar energy cell performance degeneration prediction through calculating a volt-ampere characteristic. According to the method, coupling effects of a space thermal vacuum environment and a radiation environment on the GaAs solar energy cell are considered, through establishing the one-dimensional model of the GaAs solar energy cell in the space environment, based on a minority continuity equation, degeneration case of the solar cell is analyzed and obtained through the volt-ampere characteristic. he invention has a practical value and a broad application prospect in the spatial solar cell electrical performance test technology field.

The invention is a simulation method based on potential distribution of corona discharge space. Based on Poisson equation and particle continuity equation, the simulation model adds the Navier-stokes equation which can describe the mobility of particle. The reason is that corona discharge is a process of particle movement and collision, the rapid movement of particle can cause the gas flow in discharge space and can influence the potential distribution in space. Coupling the Navier stokes equation which can describe the mobility of particle with Poisson equation and particle continuity equation, the method gets the potential contribution on the surface of sample through adjusting the parameter of simulation model, then, comparing the potential contribution with the measurement result of potential on the surface of sample to verify the effectiveness of the model. The method can calculate the potential distribution of discharge space rapidly which comprises potential distribution on the surface of sample. The method provides significant theoretical support for studying corona discharge mechanism, microscopic discharge process and simulating the effect of polarization of material.

The present invention discloses a method for calculation of characteristic lines of a three-dimensional ionized field of a direct current transmission line. The method can be used for calculation of direct current three-dimensional ionized fields of line crossing and around the surface structures and insulators. The method comprises: giving an assumed distribution of a space electric field and of space charges, calculating a new space electric field distribution by employing the space charges through the Poisson equation, and painting characteristic lines; solving the charge distribution on the characteristic lines according to the new space electric field distribution through the ion current equation and the current continuity equation; and repeating the steps mentioned above until the distributions of two successive space charges is in an allowable error range, and performing calculation of combination of the electric field and the ion current density. Compared to the Deutsch hypothesis method, the method for calculation of characteristic lines of the three-dimensional ionized field of direct current transmission line considers the influence of the space charges and is more accurate in calculation result; and moreover, compared to the finite element method, the method for calculation of characteristic lines of the three-dimensional ionized field of direct current transmission line greatly increases the update efficiency of charges and is obviously better than the finite element method on the computational efficiency.

The invention relates to a trajectory planning method for variable speed drop of composite press. The trajectory planning method comprises: first, the differential command signals are input in a proportional pilot control valve to control the circulation drop of the press and collect signals of the movable beam displacement, return cylinder pressure and instruction; then, the movable beam displacement is treated by differential method to get the falling velocity signal of movable beam and the mathematical model of valve flow is obtained by training the collected parameters by neural network algorithm; then, combining the force balance equation of the return cylinder and the continuity equation of the flow, a comprehensive mathematical model of the falling system is built; finally, with the error integral of the return cylinder pressure as the optimization index, the improved genetic algorithm is used to optimize the cubic wire interpolation trajectory, and the control trajectory of the moving beam falling is obtained. The trajectory planning method for variable speed drop of composite press adopts the movable beam falling instruction path planning method can effectively avoid the impact of rigid and flexible impact system, restrain the system pressure fluctuations and improve the efficiency and accuracy of trajectory planning activities to enhance the transmission beam falling, improving engineering adaptability.

The method for estimating corona power loss in a dust-loaded electrostatic precipitator numerically solves Poisson's equation and current continuity equations in which the finite element method (FEM) and a modified method of characteristics (MMC) are used. The system is a computerized system that produces results showing how different parameters such as discharging wire radius, wire-to-wire spacing, wire-to-plate spacing, fly ash flow speed and applied voltage polarity influence corona power loss and current density profiles.

The invention relates to the technical field of geological prospecting and discloses a method for calculating secondary migration rate of crude oil driven by overpressure. The method includes: acquiring an overpressure driven fluid flowing basic equation through a continuity equation, a Darcy law, a fluid potential expression and a formation fluid physical property relation, and converting the basic equation into an oil-water two-phase flowing equation by taking capillary pressure and oil-water saturation degree into consideration; discretizing the flowing equation through a finite difference explicit format method to acquire an explicit expression; solving the explicit expression to acquire hole pressure, and calculating on the basis of the hole pressure to acquire the secondary migration rate of the crude oil driven by overpressure. The secondary migration rate of the crude oil driven by overpressure in an overpressure reservoir is calculated by combining flowing characteristics and physical property characteristics of fluid in the overpressure reservoir through geological modeling, mathematical deduction and solving, migration distance of overpressure driven oil gas and crude oil distribution range can be acquired further, and a scientific basis is provided for geological evaluation and exploration of oil gas and finding of new oil gas reserves.

The invention discloses a full three-dimensional simulation method for an acidification flow experiment. According to the method, a differential method is utilized to discrete a fluid seepage continuity equation and an acid-liquid mass diffusion reaction equation, and an H+ local equilibrium equation, a porosity change equation, a permeability change equation and a pore throat radius change equation are established at the same time; initial conditions and boundary conditions are substituted into the simulation equations; a simulation program is compiled by utilizing the equations, the initialconditions and the boundary conditions; 6, reservoir cores are scanned to obtain three-dimensional spatial distribution parameters of porosity; a three-dimensional spatial distribution model of the porosity is established, and the compiled program is utilized to achieve full three-dimensional numerical simulation of the acidification flow experiment on the basis of the established three-dimensional spatial distribution model of the porosity. According to the method, full three-dimensional numerical calculation is adopted, the calculation precision is effectively improved, and meanwhile the influence laws of each parameter on the development of wormholes are conveniently, quickly and accurately studied.

The invention discloses an identification method for pump station characteristic curve coefficients of a one-dimensional hydrodynamic model, and relates to the technical field of hydrodynamic model parameter identification. The method comprises the steps that a one-dimensional open channel hydrodynamic model of a target open channel is built on the basis of a Saint-Venant equation, and roughness coefficients of a front connection channel and a back connection channel of a to-be-identified pump station are calibrated; the to-be-identified pump station boundary takes a continuity equation and apump station characteristic curve as consistency equations to be coupled with the Saint-Venant equation in the step 1 to form a one-dimensional channel-pump station hydrodynamic model containing the to-be-identified pump station boundary; state-space equations including the state equation X<n+1>=phi<n>X<n>+w<n+1> and the measurement equation Y<n+1>=HX<n+1>+v<n+1> which take the three pump stationcharacteristic curve coefficients of the to-be-identified pump station as state vectors are constructed; and observation data obtained in the time period when the angle or rotating speed of a pump station unit is invariable is selected, and a Kalman filter set is called to assimilate the curve coefficients. According to the method, the curve coefficients under any working conditions are automatically identified, and therefore the value simulation precision and adaptability of the river network hydrodynamic model are effectively improved.

The invention discloses an oil-water two-phase non-Darcy seepage numerical simulation method based on a discrete fracture model, and the method comprises the steps: determining an oil-water two-phaseseepage mode, and selecting a low-speed non-Darcy seepage model in a fracture system; selecting a low-speed nonlinear seepage model in the matrix for characterization; establishing continuity equations of an oil phase and a water phase respectively according to the law of conservation of mass; discretizing the continuity equation, and establishing a numerical simulation model; correcting the numerical simulation model by using an embedded discrete fracture model, adding a variety of non-adjacent link information, and establishing a nonlinear equation system; solving the nonlinear equation system to obtain oil-water two-phase pressure and saturation parameters; establishing a water-oil displacement model under a complex fracture condition, performing numerical simulation, and analyzing output characteristics of an injection well and an oil production well. The problem that an existing commercial numerical simulation method cannot simulate two-phase low-speed non-darcy flow in a matrix is solved, and the method has obvious advantages in the aspects of calculation precision and calculation efficiency.

The invention discloses a two-dimensional numerical simulation method of a tsunami wave overtopping process. The method comprises the steps that 1, the numerical water channel element form is determined according to the seawall outline; 2, initial wave height valves needed by wave pushing plate wave making are generated iteratively according to a target wave height of a tsunami wave; 3, through adirectly-discrete continuity equation and N-S equation in a lagrangian form, fluid motion is controlled, and the tsunami wave overtopping process is simulated to obtain the motion form, a flow velocity field and a pressure field of the wave; 4, the output results are calculated to obtain the maximal impact pressure value and the position of the maximal impact pressure value. By means of the method, the whole tsunami wave overtopping process and a changing process of the flow velocity field can be simulated, and the overtopping rate and the overtopping flow velocity of the top of a seawall canbe calculated to obtain the maximal impact pressure point of a seawall body and the position of the maximal impact pressure point.

A system for measuring flow rate in a pipeline by use of a surface jet pump that receives input from both a high pressure pipeline and a low pressure pipeline. Rather than installing flow meters at any or all of the inputs/output from the SJP which is an expensive undertaking, flow rate is predicted by utilising existing pressure sensors located on the high pressure pipeline, low pressure pipeline and discharge pipeline respectively. A control processor predicts flow rate based on correlations between flow rate and pressure for a given SJP geometry and, for example, utilises momentum, conservation of mass and continuity equations, balanced against the pressure forces and velocity in the SJP.

The invention relates to a complex frequency domain calculation method for a converter transformer alternating current and direct current composite electric field, which comprises the following steps:obtaining a finite element equation by combining a Galerkin method based on a full current density continuity equation of a lossy medium; expressing each periodic variable in the equation under the AC/DC composite excitation by using a complex stage number; obtaining a unit matrix equation by using the equal harmonic coefficients, and superposing all the units to obtain a system matrix equation;introducing fixed-point conductivity, and converting an iterative equation into distribution according to harmonic frequency by performing row and column change on the matrix; and selecting fixed point conductivity, carrying out iterative solution according to a set convergence criterion, and carrying out convergence to obtain a potential value. According to the method, the finite element stiffness matrix of each iteration is decomposed according to the harmonic frequency by adopting a fixed-point method, so that the memory consumption of a harmonic balance algorithm is reduced, and the calculation cost for analyzing a nonlinear alternating-current and direct-current composite electric field can be effectively reduced.

The invention provides a physical simulation experiment construction method for a horizontal well model of a bottom water sandstone oil reservoir. The method comprises the following steps of obtainingbasic characteristics of the horizontal well model of the bottom water sandstone oil reservoir; establishing basic assumed conditions of a physical simulation experiment; selecting multiple equationsdescribing the horizontal well model of the bottom water sandstone oil reservoir, and combining the equations with a compressibility equation, a capillary force equation and initial and boundary conditions of an actual oil reservoir to obtain a mathematic model of the horizontal well model of the bottom water sandstone oil reservoir, wherein the equations include a continuity equation, a seepagemotion equation and a shaft internal pressure loss equation; according to the mathematic model, determining multiple basic quantities and parameters, and performing derivation to obtain multiple similarity parameters; analyzing the sensitivity of all the similarity parameters, and determining a fitting sequence of the similarity parameters in a physical simulation experiment construction process;according to the fitting sequence, fitting the similarity parameters, and determining parameters of a physical simulation experiment model needed to be built; and according to the parameters, buildingthe physical simulation experiment model for performing the physical simulation experiment.

The invention discloses a method and a device for determining a corona initial voltage. The disclosed method comprises the steps of: calculating a potential distribution value of a boundary region ofa nominal electric field when a specified voltage is applied to a selected electrode model based on a charge simulation method; solving a Laplace equation based on an SOR algorithm to calculate a potential distribution value of a non-boundary region of the nominal electric field; and iteratively performing the steps of solving a charge continuity equation by using an FCT algorithm based on the potential distribution value of the nominal electric field at the first time or based on the potential distribution value obtained through calculation by calling the SOR algorithm previously when not atthe first time, calculating a potential distribution value corresponding to the called SOR algorithm at this time by adopting the SOR algorithm, and determining the potential distribution value as a corona initial voltage corresponding to a designated position when the designated position meets a corona generating condition. The disclosed method and device can determine the corona initial voltagedirectly by adopting the method different from a numerical value calculation method in the prior art without performing an experiment.

The invention discloses an evaluation method of mine submergence process under different water inrush or permeability conditions, which comprises establishing a conceptual model of mine water inrush or permeability submergence process according to the variation characteristics of water inrush or permeability flow rate and the spatial structure characteristics of the mine; constructing one-dimensional directional topological structure model of mine network; the continuity equation and momentum equation are established on the mine section respectively, and the connection equation is establishedat the fork point. Combined with the initial condition and boundary condition, the mathematical model of water inrush or permeability submergence process is established with the water level and discharge as variables. The finite difference algorithm is used to establish the numerical model of mine water inrush or permeability submergence process and to solve it. Quantitative evaluation of mine submergence process is carried out according to the result of solution. The invention can accurately calculate and reasonably evaluate the mine submergence process on the premise of guaranteeing the calculation stability and efficiency according to different water inrush (permeability) conditions.

Embodiments of the invention disclose a polymer flooding seepage simulation method and system. The method comprises the following steps of: obtaining oil-phase, water-phase and gas-phase state equations abided by polymer flooding on the basis of a plurality of pre-established mathematic representation equations; and solving preset oil-phase, water-phase and gas-phase continuous equations abided byconventional polymer flooding and a mass transfer diffusion equation when chemical matters in polymer systems are transferred in water on the basis of the established state equations so as to realizepolymer flooding seepage simulation. The plurality of mathematic representation equations comprises a polymer mechanical degradation mathematic representation equation, a polymer dynamic adsorption mathematic representation equation, a polymer blockage mechanism mathematic representation equation and a polymer tackifying characteristic mathematic representation equation. Through the method and system, the problems that the current polymer flooding simulation method insufficiently describes a part of important polymer flooding seepage mechanisms and cannot satisfy demands of field applications, and the availability, pertinence and correctness of a part of block simulation results are limited are solved.