The operator-splitting methods for the mathematic model of one kind of oin reactions for the problem of groundwater are considered.Optimal error estimates in L 2 and H 1 norm are obtained for the approximation solut...The operator-splitting methods for the mathematic model of one kind of oin reactions for the problem of groundwater are considered.Optimal error estimates in L 2 and H 1 norm are obtained for the approximation solution.展开更多
For the three-dimensional compressible multicomponent displacement problem we put forward the modified method of characteristics with finite element operator-splitting procedures and make use of operator-splitting,cha...For the three-dimensional compressible multicomponent displacement problem we put forward the modified method of characteristics with finite element operator-splitting procedures and make use of operator-splitting,characteristic method,calculus of variations,energy method,negative norm estimate,two kinds of test functions and the theory of prior estimates and techniques.Optimal order estimates in L^2 norm are derived for the error in the approximate solution.These methods have been successfully used in oil-gas resources estimation,enhanced oil recovery simulation and seawater intrusion numerical simulation.展开更多
An operator-splitting algorithm for the three-dimensional convection-diffusion equa- tion is presented.The flow region is discretized into tetrahedronal elements which are fixed in time. The transport equation is spli...An operator-splitting algorithm for the three-dimensional convection-diffusion equa- tion is presented.The flow region is discretized into tetrahedronal elements which are fixed in time. The transport equation is split into two successive initial value problems:a pure convection problem and a pure diffusion problem.For the pure convection problem,solutions are found by the method of characteristiCS.The solution algorithm involves tracing the characteristic lines backwards in time from a vertex of an element to an interior point.A cubic polynomial is used to interpolate the concentration and its derivatives within each element.For the diffusion problem,an explicit finite element algorithm is employed.Numerical examples are given which agree well with the analytical solutions.展开更多
This paper presents an Operator -Splitting Method (OSM) for the solution of the universal Reynolds equation. Jakoobsson-Floberg-Olsson (JFO) pressure conditions were incorporated for the study of cavitation in a liqui...This paper presents an Operator -Splitting Method (OSM) for the solution of the universal Reynolds equation. Jakoobsson-Floberg-Olsson (JFO) pressure conditions were incorporated for the study of cavitation in a liquid-lubricated journal bearings. Shear flow component of the oil film was first solved by a modified upwind finite difference method. The solution of the pressure gradient flow component was completed by the Galerkin finite element method. Present OSM solutions for a slider bearing are in agreement with Elord's results. OSM was then applied to herringbone grooved journal bearing in this work. The film pressure, cavitation areas, load capacity and attitude angle were obtained with JFO pressure conditions. The calculated load capacities are in agreement with Hirs's experimental data. A comparison of the present results and those predicted by the Reynolds pressure conditions shows some differences. The numerical results indicate that the load capacity and the critical mass of journal (linear stability indicator) are higher, and the attitude angle is lower than those predicted by Reynolds pressure conditions in cases of high eccentricities.展开更多
A numerical method for coupled solution of the equations of groundwater flow and pollution transportation is presented on the basis of operator-splitting algorithm, and the application of Kalman filtering technique in...A numerical method for coupled solution of the equations of groundwater flow and pollution transportation is presented on the basis of operator-splitting algorithm, and the application of Kalman filtering technique into the study of groundwater pollution are explored also in the present paper. Computative examples indicate that the numerical method and application of Kalman theory can avoid the unhealthy tendencies in numerical modeling and hence attain the computative accuracy considerably.展开更多
Few works use the fully three-dimensional computational fluid dynamic method to simulate the flow fields around the marine pipes with large aspect ratios due to the huge computation cost.In the present work,an operato...Few works use the fully three-dimensional computational fluid dynamic method to simulate the flow fields around the marine pipes with large aspect ratios due to the huge computation cost.In the present work,an operator-splitting method is used to efficiently solve the three-dimensional Reynolds Average Navier-Stokes governing equations of the fluid flow around pipes by separating the problem as a combination of a two-dimensional problem in the horizontal plane and an one-dimensional problem in the vertical direction.A second order total variation diminishing finite volume method is used to solve the model.The precision of the present model is validated by comparing the present numerical results of two typical three-dimensional cases with the available experimental and numerical results.The simulation results with a commercial software are also included in the comparison and the present model shows a higher performance in terms of computational time.展开更多
基金the National Sciences Foundation of China and the Doctorial Program of Higher Edua-tion
文摘The operator-splitting methods for the mathematic model of one kind of oin reactions for the problem of groundwater are considered.Optimal error estimates in L 2 and H 1 norm are obtained for the approximation solution.
基金This research is supported by the Major State Research Program of China(Grant No.19990328),the National Natural Sciences Foundation of China(Grant Nos.19871051 and 19972039),the National Tackling Key Problems Program and the Doctorate Foundation of the S
文摘For the three-dimensional compressible multicomponent displacement problem we put forward the modified method of characteristics with finite element operator-splitting procedures and make use of operator-splitting,characteristic method,calculus of variations,energy method,negative norm estimate,two kinds of test functions and the theory of prior estimates and techniques.Optimal order estimates in L^2 norm are derived for the error in the approximate solution.These methods have been successfully used in oil-gas resources estimation,enhanced oil recovery simulation and seawater intrusion numerical simulation.
文摘An operator-splitting algorithm for the three-dimensional convection-diffusion equa- tion is presented.The flow region is discretized into tetrahedronal elements which are fixed in time. The transport equation is split into two successive initial value problems:a pure convection problem and a pure diffusion problem.For the pure convection problem,solutions are found by the method of characteristiCS.The solution algorithm involves tracing the characteristic lines backwards in time from a vertex of an element to an interior point.A cubic polynomial is used to interpolate the concentration and its derivatives within each element.For the diffusion problem,an explicit finite element algorithm is employed.Numerical examples are given which agree well with the analytical solutions.
文摘This paper presents an Operator -Splitting Method (OSM) for the solution of the universal Reynolds equation. Jakoobsson-Floberg-Olsson (JFO) pressure conditions were incorporated for the study of cavitation in a liquid-lubricated journal bearings. Shear flow component of the oil film was first solved by a modified upwind finite difference method. The solution of the pressure gradient flow component was completed by the Galerkin finite element method. Present OSM solutions for a slider bearing are in agreement with Elord's results. OSM was then applied to herringbone grooved journal bearing in this work. The film pressure, cavitation areas, load capacity and attitude angle were obtained with JFO pressure conditions. The calculated load capacities are in agreement with Hirs's experimental data. A comparison of the present results and those predicted by the Reynolds pressure conditions shows some differences. The numerical results indicate that the load capacity and the critical mass of journal (linear stability indicator) are higher, and the attitude angle is lower than those predicted by Reynolds pressure conditions in cases of high eccentricities.
文摘A numerical method for coupled solution of the equations of groundwater flow and pollution transportation is presented on the basis of operator-splitting algorithm, and the application of Kalman filtering technique into the study of groundwater pollution are explored also in the present paper. Computative examples indicate that the numerical method and application of Kalman theory can avoid the unhealthy tendencies in numerical modeling and hence attain the computative accuracy considerably.
基金The authors are grateful to the financial support from the National Natural Science Foundation of China(Grant No.11372188,51490674)the National Basic Research Pro-gram of China(973 Program)(Grant No.2015CB251203).
文摘Few works use the fully three-dimensional computational fluid dynamic method to simulate the flow fields around the marine pipes with large aspect ratios due to the huge computation cost.In the present work,an operator-splitting method is used to efficiently solve the three-dimensional Reynolds Average Navier-Stokes governing equations of the fluid flow around pipes by separating the problem as a combination of a two-dimensional problem in the horizontal plane and an one-dimensional problem in the vertical direction.A second order total variation diminishing finite volume method is used to solve the model.The precision of the present model is validated by comparing the present numerical results of two typical three-dimensional cases with the available experimental and numerical results.The simulation results with a commercial software are also included in the comparison and the present model shows a higher performance in terms of computational time.
