Multi-fluid k-e-kp, two phase turbulence model is used to simulate charged gas-liquid two phase coaxial jet, which is the transorting flow field in electrostatic spraying. Compared with the results of experiment, cha...Multi-fluid k-e-kp, two phase turbulence model is used to simulate charged gas-liquid two phase coaxial jet, which is the transorting flow field in electrostatic spraying. Compared with the results of experiment, charged gas-liquid two-phase turbulence can be well predicted by this model.展开更多
Hemoglobin was used as a mimetic enzyme for peroxidase to catalyze the oxidative reaction of o-phenylenediamine with H2O2 which functioned as an oxidant. The relationship between physicochemical properties of the inte...Hemoglobin was used as a mimetic enzyme for peroxidase to catalyze the oxidative reaction of o-phenylenediamine with H2O2 which functioned as an oxidant. The relationship between physicochemical properties of the intermediate and enzymatic activity of hemoglobin was studied. Since the solubility of the intermediate in the reaction is higher in butanol phase than in water phase, the intermediate itself diffused from the aqueous phase to the butanol phase. The experimental results showed that the rate of product and the stability of intermediate were associated with the temperature and the pH value of the buffer. The formation rate of intermediate and half-life period reveal the maximal in pH7, nevertheless, the whole rate of the catalytic reaction is the greatest in pH5, which the ratio of the initial rate in final product formation compared to that intermediate formation is the greatest.展开更多
We study the mathematical model of two phase compressible flows through porous media. Under the condition that the compressibility of rock, oil, and water is small, we prove that the initial-boundary value problem of ...We study the mathematical model of two phase compressible flows through porous media. Under the condition that the compressibility of rock, oil, and water is small, we prove that the initial-boundary value problem of the nonlinear system of equations admits a weak solution.展开更多
In distributed parallel server system, location and redundancy of repficas have great influence on availability and efficiency of the system. In order to improve availability and efficiency of the system, two phase de...In distributed parallel server system, location and redundancy of repficas have great influence on availability and efficiency of the system. In order to improve availability and efficiency of the system, two phase decision algorithm of replica allocation is proposed. The algorithm which makes use of auto-regression model dynamically predicts the future count of READ and WRITE operation, and then determines location and redundancy of replicas by considering availability, CPU and bands of the network. The algorithm can not only ensure the requirement of availability, but also reduce the system resources consumed by all the operations in a great scale. Analysis and test show that communication complexity and time complexity of the algorithm satisfy O(n), resource optimizing scale increases with the increase of READ count.展开更多
This paper presents nonlinear ordinary differential equations (ODES) of the heavier pellets movement for two phase flow, which actually represent a system of equations. The usual methods of solution such as Runge -Kut...This paper presents nonlinear ordinary differential equations (ODES) of the heavier pellets movement for two phase flow, which actually represent a system of equations. The usual methods of solution such as Runge -Kutta method and it's datum results are discussed. This paper solves ODES of general form using variable mesh-length, linearizing the nonlinear terms by finite analysis method, fuilding an iteration sequence, and amending the nonlinear terms by iteration . The conditions of convergent operation of iteration solution is checked. The movement orbit and velocity of the pellets are calculated. Analysis of research results and it's application examples are illustrated.展开更多
According to the recently developed single-trough floating machine with the world's largest volume(inflatable mechanical agitation flotation machine with volume of 320 m3) in China, the gas-fluid two-phase flow in...According to the recently developed single-trough floating machine with the world's largest volume(inflatable mechanical agitation flotation machine with volume of 320 m3) in China, the gas-fluid two-phase flow in flotation cell was simulated using computational fluid dynamics method. It is shown that hexahedral mesh scheme is more suitable for the complex structure of the flotation cell than tetrahedral mesh scheme, and a mesh quality ranging from 0.7 to 1.0 is obtained. Comparative studies of the standard k-ε, k-ω and realizable k-ε turbulence models were carried out. It is indicated that the standard k-ε turbulence model could give a result relatively close to the practice and the liquid phase flow field is well characterized. In addition, two obvious recirculation zones are formed in the mixing zones, and the pressure on the rotor and stator is well characterized. Furthermore, the simulation results using improved standard k-ε turbulence model show that surface tension coefficient of 0.072, drag model of Grace and coefficient of 4, and lift coefficient of 0.001 can be achieved. The research results suggest that gas-fluid two-phase flow in large flotation cell can be well simulated using computational fluid dynamics method.展开更多
A hybrid GMDH neural network model has been developed in order to predict the partition coefficients of invertase from Baker's yeast. ATPS experiments were carried out changing the molar average mass of PEG(1500–...A hybrid GMDH neural network model has been developed in order to predict the partition coefficients of invertase from Baker's yeast. ATPS experiments were carried out changing the molar average mass of PEG(1500–6000 Da), p H(4.0–7.0), percentage of PEG(10.0–20.0 w/w), percentage of MgSO_4(8.0–16.0 w/w), percentage of the cell homogenate(10.0–20.0 w/w) and the percentage of MnSO_4(0–5.0 w/w) added as cosolute. The network evaluation was carried out comparing the partition coefficients obtained from the hybrid GMDH neural network with the experimental data using different statistical metrics. The hybrid GMDH neural network model showed better fitting(AARD = 32.752%) as well as good generalization capacity of the partition coefficients of the ATPS than the original GMDH network approach and a BPANN model. Therefore hybrid GMDH neural network model appears as a powerful tool for predicting partition coefficients during downstream processing of biomolecules.展开更多
This paper investigates the development,the breakdown process,and the discharge path selection of the lightning discharges in two-phase mixtures(TPMs).13 kinds of solid-gas mixtures and 3 kinds of liquid-gas mixtures ...This paper investigates the development,the breakdown process,and the discharge path selection of the lightning discharges in two-phase mixtures(TPMs).13 kinds of solid-gas mixtures and 3 kinds of liquid-gas mixtures are employed to study effect of two phase mixtures on the selection of the discharge path under lightning impulses.Grain size effects are shown upon these experimental results.When the diameter of solid or liquid grains is less than about 10 μm,the discharge path does not select TPM but air.And the discharge path selects TPM when the diameter is greater than about 100 μm.And when the diameter is between about 10 μm and 100 μm,the discharge path selects TPM under negative lightning impulses,but it has a greater selection of air than TPMs under positive lightning impulses.Volume fraction and permittivity of solid/liquid can also influence the selection of the discharge path.展开更多
When there exists anisotropy in underground media elastic parameters of the observed coordinate possibly do not coincide with that of the natural coordinate. According to the theory that the density of potential energ...When there exists anisotropy in underground media elastic parameters of the observed coordinate possibly do not coincide with that of the natural coordinate. According to the theory that the density of potential energy, dissipating energy is independent of the coordinate, the relationship of elastic parameters between two coordinates is derived for two-phase anisotropic media. Then, pseudospectral method to solve wave equations of two-phase anisotropic media is derived. At last, we use this method to simulate wave propagation in two-phase anisotropic media four types of waves are observed in the snapshots, i.e., fast P wave and slow P wave, fast S wave and slow S wave. Shear wave splitting, SV wave cusps and elastic wave reflection and transmission are also observed.展开更多
In the investigation of effect of KSCN on the partitioning of lysozyme in PEG2000/ammonium sulfate aqueous two-phase system, it was found that the KSCN could alter the pH difference between the two phases. and thus af...In the investigation of effect of KSCN on the partitioning of lysozyme in PEG2000/ammonium sulfate aqueous two-phase system, it was found that the KSCN could alter the pH difference between the two phases. and thus affect the partition of lysozyme. The relationship between partition coefficients of lysozyme and pH differences between two phases was discussed.展开更多
Vapor-water two phase flow separation in pressure vessel of nuclear power plants is accomplished with swirl motion using vanes. In order to reduce separation pressure loss and to make it economic, a new type of low co...Vapor-water two phase flow separation in pressure vessel of nuclear power plants is accomplished with swirl motion using vanes. In order to reduce separation pressure loss and to make it economic, a new type of low cost simplified innovative separator using lattice core configuration is proposed where swirling is caused by the orthogonal driving flow. The performance of the separator has been assessed numerically with the commercial CFD code FLUENT 14.0. The numerical analysis is compared with the experiment. The geometry and flow conditions are chosen according to the experiment. In the analysis, standard k – e and realizable k – e turbulence models are implemented. The prediction of maximum air void fraction with realizable k – e model was almost the same as input air void fraction but the void fraction computed by standard k – e model was compared better with the experimental results than the realizable k – e model. Some discrepancies in flow pattern between the experimental and simulation results are observed which might be due to the difference of nozzle shape. However, a more detailed model is necessary to arrive at the final conclusion.展开更多
This study is concerned with developing a two-dimensional two-phase model that simulate the movement of non-aqueous phase liquid (NAPL) in a fracture-rock matrix system. The intrinsic permeability and the fracture ape...This study is concerned with developing a two-dimensional two-phase model that simulate the movement of non-aqueous phase liquid (NAPL) in a fracture-rock matrix system. The intrinsic permeability and the fracture aperture are represented in the model via its KarhunenLoeve expansion. Other parameters and the nodal unknowns, water saturations and water pressures, are represented by their stochastic spectral expansions. The errors resulting from truncation of Karhunen - Loeve and polynomial chaos expansions to a finite number of terms are analyzed. The eigenvalues of stochastic process is found out for any point in the special domain of the problem at any instant in time.展开更多
This paper presents a k-e-kp multi-fluid model for simulating confined swirling gas-solid two phase jet comprised of particle-laden flow from a center tube and a swirling air stream entering the test section from the ...This paper presents a k-e-kp multi-fluid model for simulating confined swirling gas-solid two phase jet comprised of particle-laden flow from a center tube and a swirling air stream entering the test section from the coaxial annular. A series of numerical simulations of the two-phase flow of 30μm, 45μm, 60μm diameter particles respectively yielded results fitting well with published experimental data.展开更多
In this paper, we proposed a spectral gradient-Newton two phase method for constrained semismooth equations. In the first stage, we use the spectral projected gradient to obtain the global convergence of the algorithm...In this paper, we proposed a spectral gradient-Newton two phase method for constrained semismooth equations. In the first stage, we use the spectral projected gradient to obtain the global convergence of the algorithm, and then use the final point in the first stage as a new initial point to turn to a projected semismooth asymptotically newton method for fast convergence.展开更多
The competitive iodide/iodate reaction scheme was used to ascertain the micromixing in the stirred solid-liquid systems. Two different glass beads from 450 to 1250 μm were tested. The effect of solid particles on rea...The competitive iodide/iodate reaction scheme was used to ascertain the micromixing in the stirred solid-liquid systems. Two different glass beads from 450 to 1250 μm were tested. The effect of solid particles on reaction selectivity with multiple impellers at different feed points has been investigated. It was confirmed that glass beads as a second phase were suitable for the study. The segregation index has changed significantly only for the medium-sized particles at relatively high solid holdups. The cloud formation was clearly observed for the medium-sized particles at a concentration of 12.12 wt. %. When feeding into the clear liquid above the cloud, the value of the segregation index increased significantly. However, in the presence of particles of 1-1.25 mm, the influence on the selectivity was negligible when the agitation speed was increased.展开更多
Determination of turbulent mixing rate of two phase flow between neighboring subchannels is an important aspect of sub channel analysis in reactor rod bundles. Various models have been developed for two phase turbulen...Determination of turbulent mixing rate of two phase flow between neighboring subchannels is an important aspect of sub channel analysis in reactor rod bundles. Various models have been developed for two phase turbulent mixing rate between subchannels. These models show that turbulent mixing rate is strongly dependent on flow regimes;their validity was examined against specific or limited experiments. It is vital to evaluate these models by comparing the predicted two phase turbulent mixing rate with available experimental data conducted for various subchannel geometries and operating conditions. This paper describes evaluation of different models for two phase turbulent mixing rate for both gas and liquid phase against large range of experimental data which are obtained from various subchannel geometries. The results indicate that there is large discrepancy between the predicted and experimental data for turbulent mixing rate. This paper provides important shortcoming of the previous work and need for the development of a new model. In the view of this, a two phase flow model is presented, which predicts both liquid and gas phase turbulent mixing rate between adjacent sub channels of reactor rod bundles. The model presented here is for slug churn flow regime, which is dominant as compared to the other regimes like bubbly flow and annular flow regimes, since turbulent mixing rate is the highest in slug churn flow regime. The present model has been tested against low pressure and temperature air-water and high pressure and temperature steam-water experimental data found that it shows good agreement with available experimental data.展开更多
The upwind scheme is very important in the numerical approximation of some problems such as the convection dominated problem, the two-phase flow problem, and so on. For the fractional flow formulation of the two-phase...The upwind scheme is very important in the numerical approximation of some problems such as the convection dominated problem, the two-phase flow problem, and so on. For the fractional flow formulation of the two-phase flow problem, the Penalty Discontinuous Galerkin (PDG) methods combined with the upwind scheme are usually used to solve the phase pressure equation. In this case, unless the upwind scheme is taken into consideration in the velocity reconstruction, the local mass balance cannot hold exactly. In this paper, we present a scheme of velocity reconstruction in some H(div) spaces with considering the upwind scheme totally. Furthermore, the different ways to calculate the nonlinear coefficients may have distinct and significant effects, which have been investigated by some authors. We propose a new algorithm to obtain a more effective and stable approximation of the coefficients under the consideration of the upwind scheme.展开更多
The main purpose of this paper is to generalize the effect of two-phased demand and variable deterioration within the EOQ (Economic Order Quantity) framework. The rate of deterioration is a linear function of time. Th...The main purpose of this paper is to generalize the effect of two-phased demand and variable deterioration within the EOQ (Economic Order Quantity) framework. The rate of deterioration is a linear function of time. The two-phased demand function states the constant function for a certain period and the quadratic function of time for the rest part of the cycle time. No shortages as well as partial backlogging are allowed to occur. The mathematical expressions are derived for determining the optimal cycle time, order quantity and total cost function. An easy-to-use working procedure is provided to calculate the above quantities. A couple of numerical examples are cited to explain the theoretical results and sensitivity analysis of some selected examples is carried out.展开更多
This research focused on the study of heat and mass transfers in a two-phase stratified turbulent fluid flow in a geothermal pipe with chemical reaction. The derived non-linear partial differential equations governing...This research focused on the study of heat and mass transfers in a two-phase stratified turbulent fluid flow in a geothermal pipe with chemical reaction. The derived non-linear partial differential equations governing the flow were solved using the Finite Difference Method. The effects of various physical parameters on the concentration, skin friction, heat, and mass transfers have been determined. Analysis of the results obtained indicated that the coefficient of skin friction decreased with an increase in Reynolds number and solutal Grasholf number, the rate of heat transfer increased with an increase in Eckert number, Prandtl number, and angle of inclination, and the rate of mass transfer increased with increase in Reynolds number, Chemical reaction parameter and angle of inclination. The findings would be useful to engineers in designing and maintaining geothermal pipelines more effectively.展开更多
基金This project is supported by Provincial Basic Application Granting of Jiangsu(No. B197063
文摘Multi-fluid k-e-kp, two phase turbulence model is used to simulate charged gas-liquid two phase coaxial jet, which is the transorting flow field in electrostatic spraying. Compared with the results of experiment, charged gas-liquid two-phase turbulence can be well predicted by this model.
基金Supported by the National Natural Science F oundation of China( No.39770 2 0 0 )
文摘Hemoglobin was used as a mimetic enzyme for peroxidase to catalyze the oxidative reaction of o-phenylenediamine with H2O2 which functioned as an oxidant. The relationship between physicochemical properties of the intermediate and enzymatic activity of hemoglobin was studied. Since the solubility of the intermediate in the reaction is higher in butanol phase than in water phase, the intermediate itself diffused from the aqueous phase to the butanol phase. The experimental results showed that the rate of product and the stability of intermediate were associated with the temperature and the pH value of the buffer. The formation rate of intermediate and half-life period reveal the maximal in pH7, nevertheless, the whole rate of the catalytic reaction is the greatest in pH5, which the ratio of the initial rate in final product formation compared to that intermediate formation is the greatest.
基金supported by the China State Major Key Project for Basic Researches
文摘We study the mathematical model of two phase compressible flows through porous media. Under the condition that the compressibility of rock, oil, and water is small, we prove that the initial-boundary value problem of the nonlinear system of equations admits a weak solution.
文摘In distributed parallel server system, location and redundancy of repficas have great influence on availability and efficiency of the system. In order to improve availability and efficiency of the system, two phase decision algorithm of replica allocation is proposed. The algorithm which makes use of auto-regression model dynamically predicts the future count of READ and WRITE operation, and then determines location and redundancy of replicas by considering availability, CPU and bands of the network. The algorithm can not only ensure the requirement of availability, but also reduce the system resources consumed by all the operations in a great scale. Analysis and test show that communication complexity and time complexity of the algorithm satisfy O(n), resource optimizing scale increases with the increase of READ count.
文摘This paper presents nonlinear ordinary differential equations (ODES) of the heavier pellets movement for two phase flow, which actually represent a system of equations. The usual methods of solution such as Runge -Kutta method and it's datum results are discussed. This paper solves ODES of general form using variable mesh-length, linearizing the nonlinear terms by finite analysis method, fuilding an iteration sequence, and amending the nonlinear terms by iteration . The conditions of convergent operation of iteration solution is checked. The movement orbit and velocity of the pellets are calculated. Analysis of research results and it's application examples are illustrated.
基金Supported by the Natural Science Foundation of Zhejiang Province(Y1100842) the Planning Projects of General Administration of Quality Supervision Inspection and Quarantine of the People's Republic of China(2006QK23)
基金Project(51074027)supported by the National Natural Science Foundation of China
文摘According to the recently developed single-trough floating machine with the world's largest volume(inflatable mechanical agitation flotation machine with volume of 320 m3) in China, the gas-fluid two-phase flow in flotation cell was simulated using computational fluid dynamics method. It is shown that hexahedral mesh scheme is more suitable for the complex structure of the flotation cell than tetrahedral mesh scheme, and a mesh quality ranging from 0.7 to 1.0 is obtained. Comparative studies of the standard k-ε, k-ω and realizable k-ε turbulence models were carried out. It is indicated that the standard k-ε turbulence model could give a result relatively close to the practice and the liquid phase flow field is well characterized. In addition, two obvious recirculation zones are formed in the mixing zones, and the pressure on the rotor and stator is well characterized. Furthermore, the simulation results using improved standard k-ε turbulence model show that surface tension coefficient of 0.072, drag model of Grace and coefficient of 4, and lift coefficient of 0.001 can be achieved. The research results suggest that gas-fluid two-phase flow in large flotation cell can be well simulated using computational fluid dynamics method.
基金CAPES and Brazilian National Council of Research (CNPq) (Grant 407684/2013-1) for the financial support
文摘A hybrid GMDH neural network model has been developed in order to predict the partition coefficients of invertase from Baker's yeast. ATPS experiments were carried out changing the molar average mass of PEG(1500–6000 Da), p H(4.0–7.0), percentage of PEG(10.0–20.0 w/w), percentage of MgSO_4(8.0–16.0 w/w), percentage of the cell homogenate(10.0–20.0 w/w) and the percentage of MnSO_4(0–5.0 w/w) added as cosolute. The network evaluation was carried out comparing the partition coefficients obtained from the hybrid GMDH neural network with the experimental data using different statistical metrics. The hybrid GMDH neural network model showed better fitting(AARD = 32.752%) as well as good generalization capacity of the partition coefficients of the ATPS than the original GMDH network approach and a BPANN model. Therefore hybrid GMDH neural network model appears as a powerful tool for predicting partition coefficients during downstream processing of biomolecules.
基金Project Supported by National Natural Science Foundation of China(50237010).
文摘This paper investigates the development,the breakdown process,and the discharge path selection of the lightning discharges in two-phase mixtures(TPMs).13 kinds of solid-gas mixtures and 3 kinds of liquid-gas mixtures are employed to study effect of two phase mixtures on the selection of the discharge path under lightning impulses.Grain size effects are shown upon these experimental results.When the diameter of solid or liquid grains is less than about 10 μm,the discharge path does not select TPM but air.And the discharge path selects TPM when the diameter is greater than about 100 μm.And when the diameter is between about 10 μm and 100 μm,the discharge path selects TPM under negative lightning impulses,but it has a greater selection of air than TPMs under positive lightning impulses.Volume fraction and permittivity of solid/liquid can also influence the selection of the discharge path.
文摘When there exists anisotropy in underground media elastic parameters of the observed coordinate possibly do not coincide with that of the natural coordinate. According to the theory that the density of potential energy, dissipating energy is independent of the coordinate, the relationship of elastic parameters between two coordinates is derived for two-phase anisotropic media. Then, pseudospectral method to solve wave equations of two-phase anisotropic media is derived. At last, we use this method to simulate wave propagation in two-phase anisotropic media four types of waves are observed in the snapshots, i.e., fast P wave and slow P wave, fast S wave and slow S wave. Shear wave splitting, SV wave cusps and elastic wave reflection and transmission are also observed.
基金This work is supported by State Key PrO-iect of Fundamental Research !(G1998061302) the National Natural Science Foundation
文摘In the investigation of effect of KSCN on the partitioning of lysozyme in PEG2000/ammonium sulfate aqueous two-phase system, it was found that the KSCN could alter the pH difference between the two phases. and thus affect the partition of lysozyme. The relationship between partition coefficients of lysozyme and pH differences between two phases was discussed.
文摘Vapor-water two phase flow separation in pressure vessel of nuclear power plants is accomplished with swirl motion using vanes. In order to reduce separation pressure loss and to make it economic, a new type of low cost simplified innovative separator using lattice core configuration is proposed where swirling is caused by the orthogonal driving flow. The performance of the separator has been assessed numerically with the commercial CFD code FLUENT 14.0. The numerical analysis is compared with the experiment. The geometry and flow conditions are chosen according to the experiment. In the analysis, standard k – e and realizable k – e turbulence models are implemented. The prediction of maximum air void fraction with realizable k – e model was almost the same as input air void fraction but the void fraction computed by standard k – e model was compared better with the experimental results than the realizable k – e model. Some discrepancies in flow pattern between the experimental and simulation results are observed which might be due to the difference of nozzle shape. However, a more detailed model is necessary to arrive at the final conclusion.
文摘This study is concerned with developing a two-dimensional two-phase model that simulate the movement of non-aqueous phase liquid (NAPL) in a fracture-rock matrix system. The intrinsic permeability and the fracture aperture are represented in the model via its KarhunenLoeve expansion. Other parameters and the nodal unknowns, water saturations and water pressures, are represented by their stochastic spectral expansions. The errors resulting from truncation of Karhunen - Loeve and polynomial chaos expansions to a finite number of terms are analyzed. The eigenvalues of stochastic process is found out for any point in the special domain of the problem at any instant in time.
文摘This paper presents a k-e-kp multi-fluid model for simulating confined swirling gas-solid two phase jet comprised of particle-laden flow from a center tube and a swirling air stream entering the test section from the coaxial annular. A series of numerical simulations of the two-phase flow of 30μm, 45μm, 60μm diameter particles respectively yielded results fitting well with published experimental data.
文摘In this paper, we proposed a spectral gradient-Newton two phase method for constrained semismooth equations. In the first stage, we use the spectral projected gradient to obtain the global convergence of the algorithm, and then use the final point in the first stage as a new initial point to turn to a projected semismooth asymptotically newton method for fast convergence.
文摘The competitive iodide/iodate reaction scheme was used to ascertain the micromixing in the stirred solid-liquid systems. Two different glass beads from 450 to 1250 μm were tested. The effect of solid particles on reaction selectivity with multiple impellers at different feed points has been investigated. It was confirmed that glass beads as a second phase were suitable for the study. The segregation index has changed significantly only for the medium-sized particles at relatively high solid holdups. The cloud formation was clearly observed for the medium-sized particles at a concentration of 12.12 wt. %. When feeding into the clear liquid above the cloud, the value of the segregation index increased significantly. However, in the presence of particles of 1-1.25 mm, the influence on the selectivity was negligible when the agitation speed was increased.
文摘Determination of turbulent mixing rate of two phase flow between neighboring subchannels is an important aspect of sub channel analysis in reactor rod bundles. Various models have been developed for two phase turbulent mixing rate between subchannels. These models show that turbulent mixing rate is strongly dependent on flow regimes;their validity was examined against specific or limited experiments. It is vital to evaluate these models by comparing the predicted two phase turbulent mixing rate with available experimental data conducted for various subchannel geometries and operating conditions. This paper describes evaluation of different models for two phase turbulent mixing rate for both gas and liquid phase against large range of experimental data which are obtained from various subchannel geometries. The results indicate that there is large discrepancy between the predicted and experimental data for turbulent mixing rate. This paper provides important shortcoming of the previous work and need for the development of a new model. In the view of this, a two phase flow model is presented, which predicts both liquid and gas phase turbulent mixing rate between adjacent sub channels of reactor rod bundles. The model presented here is for slug churn flow regime, which is dominant as compared to the other regimes like bubbly flow and annular flow regimes, since turbulent mixing rate is the highest in slug churn flow regime. The present model has been tested against low pressure and temperature air-water and high pressure and temperature steam-water experimental data found that it shows good agreement with available experimental data.
文摘The upwind scheme is very important in the numerical approximation of some problems such as the convection dominated problem, the two-phase flow problem, and so on. For the fractional flow formulation of the two-phase flow problem, the Penalty Discontinuous Galerkin (PDG) methods combined with the upwind scheme are usually used to solve the phase pressure equation. In this case, unless the upwind scheme is taken into consideration in the velocity reconstruction, the local mass balance cannot hold exactly. In this paper, we present a scheme of velocity reconstruction in some H(div) spaces with considering the upwind scheme totally. Furthermore, the different ways to calculate the nonlinear coefficients may have distinct and significant effects, which have been investigated by some authors. We propose a new algorithm to obtain a more effective and stable approximation of the coefficients under the consideration of the upwind scheme.
文摘The main purpose of this paper is to generalize the effect of two-phased demand and variable deterioration within the EOQ (Economic Order Quantity) framework. The rate of deterioration is a linear function of time. The two-phased demand function states the constant function for a certain period and the quadratic function of time for the rest part of the cycle time. No shortages as well as partial backlogging are allowed to occur. The mathematical expressions are derived for determining the optimal cycle time, order quantity and total cost function. An easy-to-use working procedure is provided to calculate the above quantities. A couple of numerical examples are cited to explain the theoretical results and sensitivity analysis of some selected examples is carried out.
文摘This research focused on the study of heat and mass transfers in a two-phase stratified turbulent fluid flow in a geothermal pipe with chemical reaction. The derived non-linear partial differential equations governing the flow were solved using the Finite Difference Method. The effects of various physical parameters on the concentration, skin friction, heat, and mass transfers have been determined. Analysis of the results obtained indicated that the coefficient of skin friction decreased with an increase in Reynolds number and solutal Grasholf number, the rate of heat transfer increased with an increase in Eckert number, Prandtl number, and angle of inclination, and the rate of mass transfer increased with increase in Reynolds number, Chemical reaction parameter and angle of inclination. The findings would be useful to engineers in designing and maintaining geothermal pipelines more effectively.