A body force resembling the streamwise Lorentz force which decays exponentially in the wall-normalwise direction is applied in the primary and secondary separation bubbles to modify the base flow and thereby adjust th...A body force resembling the streamwise Lorentz force which decays exponentially in the wall-normalwise direction is applied in the primary and secondary separation bubbles to modify the base flow and thereby adjust the amplification rate of the perturbation energy.The amplification mechanisms are investigated numerically via analyzing the characteristics of the terms in the Reynolds-Orr equation which describes the growth rate of the perturbation energy.The results demonstrate that the main convective term always promotes the increase in the growth rate while the viscous terms usually play the reverse role.The contours of the product of the wall-normalwise and streamwise perturbation velocities distribute on both sides of the isoline,which represents the zero wall-normalwise gradient of the streamwise velocity in the base flow,due to the Kelvin-Helmholtz(KH)instability.For the case without control,the isoline downstream the reattachment point of the primary separation bubble is closer to the lower wall,and thus the viscous term near the lower wall might suppress the amplification rate.For the case in which the body force only acts on the secondary separation bubble,the secondary separation bubble is removed,and the magnitude of the negative wall-normalwise gradient of the base flow streamwise velocity decreases along the streamwise direction,and thus the growth rate of the perturbation energy is smaller than that for the case without control.For the case where the body force acts on both the separation bubbles,the secondary separation bubble is removed,the isoline stays in the central part of the channel,and thereby the viscous term has less effects on the amplification rate of which the peak value could be the maximum one for some control number.展开更多
This study investigates the motion behavior of a slender flexible particle in a backward-facing step(BFS)flow using the direct-forcing fictitious domain method,with a particular focus on the trapping phenomena near th...This study investigates the motion behavior of a slender flexible particle in a backward-facing step(BFS)flow using the direct-forcing fictitious domain method,with a particular focus on the trapping phenomena near the separation vortex region.Three distinct motion modes are identified:periodic rotation or oscillation within the vortex(trapping),downstream transport(escape),and transition state exhibiting unstable trapping.A dynamic balance among inward migration,centrifugal effects,wall interactions,and elastic forces enables the particle to achieve stable orbital motion within two distinct limit cycles.The topology of these orbits is governed by parameters,including the aspect ratio,structural flexibility,deformation intensity,and fluid inertia,all of which are characterized by the Reynolds number(Re).Specifically,fluid inertia plays a dominant role in facilitating particle trapping.At a fixed Re,a particle with a smaller aspect ratio tends to migrate inward and become trapped,whereas one with a larger aspect ratio is more likely to escape.Structural flexibility,especially when enhanced by confinement near the wall,leads to elastic deformation that induces secondary vortices and a weak flipping motion.The deformation intensityαsignificantly influences the lateral migration of the slender particle after the initial release;a largerαcauses it to drift toward the channel centerline,increasing the probability of escape.These findings provide a theoretical foundation for optimizing the transport and capture of slender soft swimmers in complex flow environments.展开更多
Flow over a backward-facing step was studied to investigate the effect of large-scale vortex structures on sediment incipience. The transient flow velocity field at the downstream of the backward-facing step was obtai...Flow over a backward-facing step was studied to investigate the effect of large-scale vortex structures on sediment incipience. The transient flow velocity field at the downstream of the backward-facing step was obtained using the technique of Particle Tracking Velocimetry （PTV）. The optical amplification technique was employed to measure the instantaneous flow velocities near the bed and the instantaneous bed shear stress was given. The experimental observations revealed a new insight into the oscillation of the large-scale structure and the three-dimensional characteristics of the flow. In particular, very high turbulence intensity, instantaneous horizontal velocity near the bed and the bed shear stress near the reattachment point were observed. The sediment incipient probability obtained from the sequent images of sediment particles near the bed indicates that the critical instantaneous shear stress of the sediment incipience is independent of flow conditions.展开更多
The tile-type electromagnetic actuator(TEA)and stripe-type electromagnetic actuator(SEA)are applied to the active control of the perturbation energy in the liquid metal flow over a backward-facing step(BFS).Three cont...The tile-type electromagnetic actuator(TEA)and stripe-type electromagnetic actuator(SEA)are applied to the active control of the perturbation energy in the liquid metal flow over a backward-facing step(BFS).Three control strategies consisting of base flow control(BFC),linear model control(LMC)and combined model control(CMC)are considered to change the amplification rate of the perturbation energy.CMC is the combination of BFC and LMC.SEA is utilized in BFC to produce the streamwise Lorentz force thus adjusting the amplification rate via modifying the flow structures,and the magnitude of the maximum amplification rate could reach to 6 orders.TEA is used in LMC to reduce the magnitude of the amplification rate via the wall-normalwise Lorentz force,and the magnitude could be decreased by 2 orders.Both TEA and SEA are employed in CMC where the magnitude of the amplification rate could be diminished by 3 orders.In other words,the control strategy of CMC could capably alter the flow instability of the liquid metal flow.展开更多
The flow structures in a separated shear layer actuated by a synthetic jet actuator were studied using experimental methods. When forced at a frequency much lower than the natural shedding frequency （fH/U = 0.042 orf...The flow structures in a separated shear layer actuated by a synthetic jet actuator were studied using experimental methods. When forced at a frequency much lower than the natural shedding frequency （fH/U = 0.042 orfXr/U = 0.24）, the vertical flapping motion of the shear layer downstream of the separation point became prominent. The size of the peak in the pressure spectra at the forcing frequency （Sta = fAH//U） measured near the separation point （x/H = 1） increased linearly with the forcing ampli- tude （u＇/U） suggesting a linear response of the pressure fluctuations to the forcing by the synthetic jet. The linear response did not hold for the pressure fluctuations away from the jet exit as the magnitude of the peak for StA measured at x/H = 3 soon saturated when the forcing amplitude became larger than 0.3.展开更多
As a widely used flood energy dissipator, the stepped spillway can significantly dissipate the kinetic or hydraulic energy due to the air-entrainment in skimming flow over the steps. The free-surface aeration involves...As a widely used flood energy dissipator, the stepped spillway can significantly dissipate the kinetic or hydraulic energy due to the air-entrainment in skimming flow over the steps. The free-surface aeration involves the sharp deformation of the free surface and the complex turbulent shear flows. In this study, the volume of fluid （VOF）, mixture, and Eulerian methods are utilized to simulate the air-entrainment by coupling with the Reynolds-averaged Navier-Stokes/large eddy simulation （RANS/LES） turbulence models. The free surface deformation, air volume fraction, pressure, and velocity are compared for the three different numerical methods. Only the Eulerian＋RANS method fails to capture the free-surface aeration. The air volume fraction predicted by the VOF＋LES method best matches the experimental measurement, while the mixture＋LES method predicts the inception point of the air entrainment more accurately.展开更多
This paper deals with some aspects of the air entrainment process along the chute of spillway and study of pressure fluctuations. The experimental study has been carried out using stepped spillway model located in the...This paper deals with some aspects of the air entrainment process along the chute of spillway and study of pressure fluctuations. The experimental study has been carried out using stepped spillway model located in the campus of Government College of Engineering, Amravati (India). It is observed that air concentration is increasing with discharge as well as with number of step. Air concentration is increasing along the length of spillway. It is also observed that the bottom mean air concentration increases with step height in the upstream reach of stepped spillway, which is prone to cavitation. The pressure profiles exhibit a wavy pattern down the stepped chute and pressure on each step increases with ratio of critical depth to step height (yc/h).展开更多
Bunching of elementary steps by solution flow is still not yet clarified for protein crystals. Hence, in this study, we observed elementary steps on crystal surfaces of model protein hen egg-white lysozyme （HEWL） un...Bunching of elementary steps by solution flow is still not yet clarified for protein crystals. Hence, in this study, we observed elementary steps on crystal surfaces of model protein hen egg-white lysozyme （HEWL） under forced flow conditions, by our advanced optical microscopy. We found that in the case of a HEWL solution of 99.99% purity, forced flow changed bunched steps into elementary ones （debunching） on tetragonal HEWL crystals. In contrast, in the case of a HEWL solution of 98.5% purity, forced flow significantly induced bunching of elementary steps. These results indicate that in the case of HEWL crystals, the mass transfer of impurities is more significantly enhanced by forced solution flow than that of solute HEWL molecules. We also showed that forced flow induced the incorporation of microcrystals into a mother crystal and the subsequent formation of screw dislocations and spiral growth hillocks.展开更多
Numerical simulations of a two-dimensional laminar forced convection flow adjacent to inclined backward-facing step in a rectangular duct are presented to examine effects of baffle on flow, heat transfer and entropy g...Numerical simulations of a two-dimensional laminar forced convection flow adjacent to inclined backward-facing step in a rectangular duct are presented to examine effects of baffle on flow, heat transfer and entropy generation distributions. The main aim of using baffles is to enhance the value of convection coefficient on the bottom wall. But the useful energy can be destroyed due to intrinsic irreversibilities in the flow by the baffle. In the present work, the amount of energy loss is estimated by the computation of entropy generation. The values of velocity and temperature which are the inputs of the entropy generation equation are obtained by the numerical solution of momentum and energy equations with blocked-off method using computational fluid dynamic technique. Discretized forms of the governing equations in the (x, y) plane are obtained by the control volume method and solved using the SIMPLE algorithm. Numerical expressions, in terms of Nusselt number, entropy generation number, Bejan number and coefficient of friction are derived in dimensionless form. Results show that although a baffle mounted onto the upper wall increases the magnitude of Nusselts number on the bottom wall, but a considerable increase in the amount of entropy generation number takes place because of this technique. For validation, the numerical results for the Nusselt number and entropy generation number are compared with theoretical findings by other investigators and reasonable agreement is found.展开更多
The experimental investigation is conducted with LDV and hydrogen bubble technique in water flow. The shear layer thickness. the vorticity thickness. the maximulll value of turbulence intensities. the turbulent coher...The experimental investigation is conducted with LDV and hydrogen bubble technique in water flow. The shear layer thickness. the vorticity thickness. the maximulll value of turbulence intensities. the turbulent coherent structure. the variations of wall shear stress and the boundary layer shape factor are obtained. In the redevelopment region. the detailed analysis is first made for the streak structures in the near wall region and the turbulent boundary layer is formed at (x-xr) / h = 20.展开更多
In the current study, a numerical investigation of three-dimensional combined convection-radiation heat transfer over an inclined forward facing step (FFS) in a horizontal rectangular duct is presented. The fluid is t...In the current study, a numerical investigation of three-dimensional combined convection-radiation heat transfer over an inclined forward facing step (FFS) in a horizontal rectangular duct is presented. The fluid is treated as a gray, absorbing, emitting and scattering medium. To simulate the incline surface of FFS, the blocked-off method is employed in this study. The set of governing equations for gas flow are solved numerically using the CFD technique to obtain the temperature and velocity fields. Since the gas is considered as a radiating medium, all of the convection, conduction and radiation heat transfer mechanisms are presented in the energy equation. For computation of radiative term in energy equation, the radiative transfer equation (RTE) is solved numerically by the discrete ordinates method (DOM) to find the divergence of radiative heat flux distribution inside the radiating medium. The effects of optical thickness, radiation-conduction parameter and albedo coefficient on heat transfer behavior of the system are carried out.展开更多
Presented in this paper is a mathematical model to calculate the probability of the sediment incipient motion, in which the effects of the fluctuating pressure and the seepage are considered. The instantaneous bed she...Presented in this paper is a mathematical model to calculate the probability of the sediment incipient motion, in which the effects of the fluctuating pressure and the seepage are considered. The instantaneous bed shear velocity and the pressure gradient on the bed downstream of the backward-facing step flow are obtained according to the PIV measurements. It is found that the instantaneous pressure gradient on the bed obeys normal distribution. The probability of the sediment incipient motion on the bed downstream of the backward-facing step flow is given by the mathematical model. The predicted results agree well with the experiment in the region downstream of the reattachment point while a large discrepancy between the theory and experiment is seen in the region near the reattachment point. The possible reasons for this discrepancy are discussed.展开更多
The distribution of remaining oil is often described qualitatively. The remaining oil distributed in the whole reservoir is calculated according to the characteristics of the space distribution of the saturation of re...The distribution of remaining oil is often described qualitatively. The remaining oil distributed in the whole reservoir is calculated according to the characteristics of the space distribution of the saturation of remaining oil. Logging data are required to accomplish this. However, many such projects cannot be completed. Since the old study of remaining oil distribution could not be quantified efficiently, the ＂dynamic two-step method＂ is presented. Firstly, the water cut of every flow unit in one well at one time is calculated according to the comprehensive water cut of a single well at one time. Secondly, the remaining oil saturation of the flow unit of the well at one time is calculated based on the water cut of the flow unit at a given time. The results show that ＂dynamic two-step method＂ has characteristics of simplicity and convenience, and is especially suitable for the study of remaining oil distribution at high water-cut stage. The distribution of remaining oil presented banding and potato form, remaining oil was relatively concentrated in faultage neighborhood and imperfect well netting position, and the net thickness of the place was great. This proposal can provide an effective way to forecast remaining oil distribution and enhance oil recovery, especially applied at the high water-cut stage.展开更多
The present contributions deal with the development and implementation of the direct and adjoint incompressible Navie-Stokes equations in a matrix-free time-stepping context making use of the open-source OpenFOAM~ （o...The present contributions deal with the development and implementation of the direct and adjoint incompressible Navie-Stokes equations in a matrix-free time-stepping context making use of the open-source OpenFOAM~ （open source field operation and manipulation） C ＋ ＋ tool- box. It is shown that a few minor modifications in the source code can enable these multi-purpose computational fluid dynamics （CFD） solvers to carry out global instability analysis of three- dimensional flows of engineering interest, exploiting all additional capabilities of such codes. The strength of this methodology is demonstrated through the analysis of an interesting selection of ooen and wall-bounded flows.展开更多
基金the National Natural Science Foundation of China (Nos. 51776087 and 51979125)。
文摘A body force resembling the streamwise Lorentz force which decays exponentially in the wall-normalwise direction is applied in the primary and secondary separation bubbles to modify the base flow and thereby adjust the amplification rate of the perturbation energy.The amplification mechanisms are investigated numerically via analyzing the characteristics of the terms in the Reynolds-Orr equation which describes the growth rate of the perturbation energy.The results demonstrate that the main convective term always promotes the increase in the growth rate while the viscous terms usually play the reverse role.The contours of the product of the wall-normalwise and streamwise perturbation velocities distribute on both sides of the isoline,which represents the zero wall-normalwise gradient of the streamwise velocity in the base flow,due to the Kelvin-Helmholtz(KH)instability.For the case without control,the isoline downstream the reattachment point of the primary separation bubble is closer to the lower wall,and thus the viscous term near the lower wall might suppress the amplification rate.For the case in which the body force only acts on the secondary separation bubble,the secondary separation bubble is removed,and the magnitude of the negative wall-normalwise gradient of the base flow streamwise velocity decreases along the streamwise direction,and thus the growth rate of the perturbation energy is smaller than that for the case without control.For the case where the body force acts on both the separation bubbles,the secondary separation bubble is removed,the isoline stays in the central part of the channel,and thereby the viscous term has less effects on the amplification rate of which the peak value could be the maximum one for some control number.
基金Project supported by the National Natural Science Foundation of China(Nos.12132015,12332015,and 12302333)。
文摘This study investigates the motion behavior of a slender flexible particle in a backward-facing step(BFS)flow using the direct-forcing fictitious domain method,with a particular focus on the trapping phenomena near the separation vortex region.Three distinct motion modes are identified:periodic rotation or oscillation within the vortex(trapping),downstream transport(escape),and transition state exhibiting unstable trapping.A dynamic balance among inward migration,centrifugal effects,wall interactions,and elastic forces enables the particle to achieve stable orbital motion within two distinct limit cycles.The topology of these orbits is governed by parameters,including the aspect ratio,structural flexibility,deformation intensity,and fluid inertia,all of which are characterized by the Reynolds number(Re).Specifically,fluid inertia plays a dominant role in facilitating particle trapping.At a fixed Re,a particle with a smaller aspect ratio tends to migrate inward and become trapped,whereas one with a larger aspect ratio is more likely to escape.Structural flexibility,especially when enhanced by confinement near the wall,leads to elastic deformation that induces secondary vortices and a weak flipping motion.The deformation intensityαsignificantly influences the lateral migration of the slender particle after the initial release;a largerαcauses it to drift toward the channel centerline,increasing the probability of escape.These findings provide a theoretical foundation for optimizing the transport and capture of slender soft swimmers in complex flow environments.
基金Project supported by the National Natural Science Foundation of China(Grant No.10602017).
文摘Flow over a backward-facing step was studied to investigate the effect of large-scale vortex structures on sediment incipience. The transient flow velocity field at the downstream of the backward-facing step was obtained using the technique of Particle Tracking Velocimetry （PTV）. The optical amplification technique was employed to measure the instantaneous flow velocities near the bed and the instantaneous bed shear stress was given. The experimental observations revealed a new insight into the oscillation of the large-scale structure and the three-dimensional characteristics of the flow. In particular, very high turbulence intensity, instantaneous horizontal velocity near the bed and the bed shear stress near the reattachment point were observed. The sediment incipient probability obtained from the sequent images of sediment particles near the bed indicates that the critical instantaneous shear stress of the sediment incipience is independent of flow conditions.
基金Project supported by the National Natural Science Foundation of China(Grant No.U2141246)
文摘The tile-type electromagnetic actuator(TEA)and stripe-type electromagnetic actuator(SEA)are applied to the active control of the perturbation energy in the liquid metal flow over a backward-facing step(BFS).Three control strategies consisting of base flow control(BFC),linear model control(LMC)and combined model control(CMC)are considered to change the amplification rate of the perturbation energy.CMC is the combination of BFC and LMC.SEA is utilized in BFC to produce the streamwise Lorentz force thus adjusting the amplification rate via modifying the flow structures,and the magnitude of the maximum amplification rate could reach to 6 orders.TEA is used in LMC to reduce the magnitude of the amplification rate via the wall-normalwise Lorentz force,and the magnitude could be decreased by 2 orders.Both TEA and SEA are employed in CMC where the magnitude of the amplification rate could be diminished by 3 orders.In other words,the control strategy of CMC could capably alter the flow instability of the liquid metal flow.
基金supported by 973 Plan (2014CB744100)Dalian University of Technology (DUT14LK07)
文摘The flow structures in a separated shear layer actuated by a synthetic jet actuator were studied using experimental methods. When forced at a frequency much lower than the natural shedding frequency （fH/U = 0.042 orfXr/U = 0.24）, the vertical flapping motion of the shear layer downstream of the separation point became prominent. The size of the peak in the pressure spectra at the forcing frequency （Sta = fAH//U） measured near the separation point （x/H = 1） increased linearly with the forcing ampli- tude （u＇/U） suggesting a linear response of the pressure fluctuations to the forcing by the synthetic jet. The linear response did not hold for the pressure fluctuations away from the jet exit as the magnitude of the peak for StA measured at x/H = 3 soon saturated when the forcing amplitude became larger than 0.3.
基金supported by the Guangdong Special Research Fund of Public Welfare and Capacity Building(2015A020216008)the Special Program for Applied Research on Super Computation of the NSFC-Guangdong Joint Fund(the second phase)
文摘As a widely used flood energy dissipator, the stepped spillway can significantly dissipate the kinetic or hydraulic energy due to the air-entrainment in skimming flow over the steps. The free-surface aeration involves the sharp deformation of the free surface and the complex turbulent shear flows. In this study, the volume of fluid （VOF）, mixture, and Eulerian methods are utilized to simulate the air-entrainment by coupling with the Reynolds-averaged Navier-Stokes/large eddy simulation （RANS/LES） turbulence models. The free surface deformation, air volume fraction, pressure, and velocity are compared for the three different numerical methods. Only the Eulerian＋RANS method fails to capture the free-surface aeration. The air volume fraction predicted by the VOF＋LES method best matches the experimental measurement, while the mixture＋LES method predicts the inception point of the air entrainment more accurately.
文摘This paper deals with some aspects of the air entrainment process along the chute of spillway and study of pressure fluctuations. The experimental study has been carried out using stepped spillway model located in the campus of Government College of Engineering, Amravati (India). It is observed that air concentration is increasing with discharge as well as with number of step. Air concentration is increasing along the length of spillway. It is also observed that the bottom mean air concentration increases with step height in the upstream reach of stepped spillway, which is prone to cavitation. The pressure profiles exhibit a wavy pattern down the stepped chute and pressure on each step increases with ratio of critical depth to step height (yc/h).
基金Chinese Academy of Sciences visiting professorship for senior international scientists(2013T2J0060)
文摘Bunching of elementary steps by solution flow is still not yet clarified for protein crystals. Hence, in this study, we observed elementary steps on crystal surfaces of model protein hen egg-white lysozyme （HEWL） under forced flow conditions, by our advanced optical microscopy. We found that in the case of a HEWL solution of 99.99% purity, forced flow changed bunched steps into elementary ones （debunching） on tetragonal HEWL crystals. In contrast, in the case of a HEWL solution of 98.5% purity, forced flow significantly induced bunching of elementary steps. These results indicate that in the case of HEWL crystals, the mass transfer of impurities is more significantly enhanced by forced solution flow than that of solute HEWL molecules. We also showed that forced flow induced the incorporation of microcrystals into a mother crystal and the subsequent formation of screw dislocations and spiral growth hillocks.
文摘Numerical simulations of a two-dimensional laminar forced convection flow adjacent to inclined backward-facing step in a rectangular duct are presented to examine effects of baffle on flow, heat transfer and entropy generation distributions. The main aim of using baffles is to enhance the value of convection coefficient on the bottom wall. But the useful energy can be destroyed due to intrinsic irreversibilities in the flow by the baffle. In the present work, the amount of energy loss is estimated by the computation of entropy generation. The values of velocity and temperature which are the inputs of the entropy generation equation are obtained by the numerical solution of momentum and energy equations with blocked-off method using computational fluid dynamic technique. Discretized forms of the governing equations in the (x, y) plane are obtained by the control volume method and solved using the SIMPLE algorithm. Numerical expressions, in terms of Nusselt number, entropy generation number, Bejan number and coefficient of friction are derived in dimensionless form. Results show that although a baffle mounted onto the upper wall increases the magnitude of Nusselts number on the bottom wall, but a considerable increase in the amount of entropy generation number takes place because of this technique. For validation, the numerical results for the Nusselt number and entropy generation number are compared with theoretical findings by other investigators and reasonable agreement is found.
文摘The experimental investigation is conducted with LDV and hydrogen bubble technique in water flow. The shear layer thickness. the vorticity thickness. the maximulll value of turbulence intensities. the turbulent coherent structure. the variations of wall shear stress and the boundary layer shape factor are obtained. In the redevelopment region. the detailed analysis is first made for the streak structures in the near wall region and the turbulent boundary layer is formed at (x-xr) / h = 20.
文摘In the current study, a numerical investigation of three-dimensional combined convection-radiation heat transfer over an inclined forward facing step (FFS) in a horizontal rectangular duct is presented. The fluid is treated as a gray, absorbing, emitting and scattering medium. To simulate the incline surface of FFS, the blocked-off method is employed in this study. The set of governing equations for gas flow are solved numerically using the CFD technique to obtain the temperature and velocity fields. Since the gas is considered as a radiating medium, all of the convection, conduction and radiation heat transfer mechanisms are presented in the energy equation. For computation of radiative term in energy equation, the radiative transfer equation (RTE) is solved numerically by the discrete ordinates method (DOM) to find the divergence of radiative heat flux distribution inside the radiating medium. The effects of optical thickness, radiation-conduction parameter and albedo coefficient on heat transfer behavior of the system are carried out.
基金supported by the National Natural Science Foundation of China (Grant No.10602017)
文摘Presented in this paper is a mathematical model to calculate the probability of the sediment incipient motion, in which the effects of the fluctuating pressure and the seepage are considered. The instantaneous bed shear velocity and the pressure gradient on the bed downstream of the backward-facing step flow are obtained according to the PIV measurements. It is found that the instantaneous pressure gradient on the bed obeys normal distribution. The probability of the sediment incipient motion on the bed downstream of the backward-facing step flow is given by the mathematical model. The predicted results agree well with the experiment in the region downstream of the reattachment point while a large discrepancy between the theory and experiment is seen in the region near the reattachment point. The possible reasons for this discrepancy are discussed.
文摘The distribution of remaining oil is often described qualitatively. The remaining oil distributed in the whole reservoir is calculated according to the characteristics of the space distribution of the saturation of remaining oil. Logging data are required to accomplish this. However, many such projects cannot be completed. Since the old study of remaining oil distribution could not be quantified efficiently, the ＂dynamic two-step method＂ is presented. Firstly, the water cut of every flow unit in one well at one time is calculated according to the comprehensive water cut of a single well at one time. Secondly, the remaining oil saturation of the flow unit of the well at one time is calculated based on the water cut of the flow unit at a given time. The results show that ＂dynamic two-step method＂ has characteristics of simplicity and convenience, and is especially suitable for the study of remaining oil distribution at high water-cut stage. The distribution of remaining oil presented banding and potato form, remaining oil was relatively concentrated in faultage neighborhood and imperfect well netting position, and the net thickness of the place was great. This proposal can provide an effective way to forecast remaining oil distribution and enhance oil recovery, especially applied at the high water-cut stage.
基金Support of the Marie Curie Grant PIRSES-GA-2009-247651‘‘FP7-PEOPLE-IRSES:ICOMASEF-Instability and Control of Massively Separated Flows”
文摘The present contributions deal with the development and implementation of the direct and adjoint incompressible Navie-Stokes equations in a matrix-free time-stepping context making use of the open-source OpenFOAM~ （open source field operation and manipulation） C ＋ ＋ tool- box. It is shown that a few minor modifications in the source code can enable these multi-purpose computational fluid dynamics （CFD） solvers to carry out global instability analysis of three- dimensional flows of engineering interest, exploiting all additional capabilities of such codes. The strength of this methodology is demonstrated through the analysis of an interesting selection of ooen and wall-bounded flows.
