A new mobile bed heat exchanger is presented in this work which is composed of a flowing granular material in a rotating drum and a cylindrical pipe with potential interest in different energy applications as cooling,...A new mobile bed heat exchanger is presented in this work which is composed of a flowing granular material in a rotating drum and a cylindrical pipe with potential interest in different energy applications as cooling,heating or heat recovery processes.An optimal design of the device requires a characterisation of the phenomena involved at the interface between the granular flow and the pipe.The process is modelled by the discrete element method and a global classification of the flow patterns around the pipe is presented with respect to the three main control parameters of the problem:the Froude number,the diameter ratio and the relative filling height of the drum.The second part is devoted to the characterisation of the structure of the flow at the interface(velocity field,density field)in particular in a so-called Biflow regime where granular motion occurs above as well as below the pipe which is favourable to transfer by convection.A typical behavior at the interface with the pipe consists of a zone I with high velocities of particles at the top of the pipe,a second zone with quasistatic particles or low velocity particles at the front and at the bottom of the pipe and a last zone ll of depletion of particles at the back of the pipe.The Froude number has a limited effect on the features of this structure on the first layer in the range of Froude numbers considered whereas the relative height is a more determinant parameter to control the relative magnitude of velocities in zone I and zone Il as well as the extent of the depletion zone.This first hydrodynamical characterisation can shed light on the dynamical regimes with improved transfer between the particles and the pipe boundary.展开更多
The present paper presents an experimental and numerical investigation of the dispersion of the gaseous jet flow and co-flow for the simple unit cell(SUC)and body-centred cubic(BCC)configuration of particles in packed...The present paper presents an experimental and numerical investigation of the dispersion of the gaseous jet flow and co-flow for the simple unit cell(SUC)and body-centred cubic(BCC)configuration of particles in packed beds.The experimental setup is built in such a way that suitable and simplified boundary conditions are imposed for the corresponding numerical framework,so the simulations can be done under very similar conditions as the experiments.Accordingly,a porous plate is used for the co-flow to achieve the uniform velocity and the fully developed flow is ensured for the jet flow.The SUC and BCC particle beds consist of 3D-printed spheres,and the non-isotropy near the walls is mostly eliminated by placing half-spheres at the channel walls.The flow velocities are analysed directly at the exit of the particle bed for both beds over 36 pores for the SUC configuration and 60 pores for the BCC configuration,for particle Reynolds numbers of 200,300,and 400.Stereo particle image velocimetry is experimentally arranged in such a way that the velocities over the entire region at the exit of the packed bed are obtained instantaneously.The numerical method consists of a state-of-the-art immersed boundary method with adaptive mesh refinement.The paper presents the pore jet structure and velocity field exiting from each pore for the SUC and BCC packed particle beds.The numerical and experimental studies show a good agreement for the SUC configuration for all flow velocities.For the BCC configuration,some differences can be observed in the pore jet flow structure between the simulations and the experiments,but the general flow velocity distribution shows a good overall agreement.The axial velocity is generally higher for the pores located near the centre of the packed bed than for the pores near the wall.In addition,the axial velocities are observed to increase near the peripheral pores of the packed bed.This behaviour is predominant for the BCC configuration as compared to the SUC configuration.The velocities near the per展开更多
Ecosystem conservation has become one of the purposes in river management as well as flood mitigation and water resources management, and understanding of river flow and morphology in a stream with vegetation becomes ...Ecosystem conservation has become one of the purposes in river management as well as flood mitigation and water resources management, and understanding of river flow and morphology in a stream with vegetation becomes important. Recently 2D depth averaged analysis is familiar even in a stream with vegetation by taking account of form drag due to vegetation. However, the shear stress in vegetated area is not properly described because the resistance law due to bed roughness is not reasonably modified in vegetated area. In this study, we discussed the bed roughness boundary layer in flow with non-submerged vegetation to deduce a reasonable relation between U and u* in vegetated area toward improving the analysis of sediment transport. The results show that the modification of resistance law using by thickness, velocity distribution in that layer was found to bring significant improvement of accurate estimation of shear velocity and subsequently the sediment transport. The proposed modification is improved by 2D depth averaged analysis based on this concept, and its application is certificated through flume experiment.展开更多
Copper element was added in pure titanium to produce a new biomedical titanium-copper alloy by laser powder bed fusion(LPBF).Addition of copper can eliminate the mismatch of high strength but poor duc-tility problem c...Copper element was added in pure titanium to produce a new biomedical titanium-copper alloy by laser powder bed fusion(LPBF).Addition of copper can eliminate the mismatch of high strength but poor duc-tility problem caused by lathα’martensite,which is the usual microstructure of nearαtitanium alloy fabricated by LPBF.Instead of by the usual trade-offrelationship between strength and ductility,which is a long-standing challenge for martensitic titanium alloys,in this study,we proposed a boundary engineer-ing strategy and aim to synergistically enhance the strength and ductility of martensitic titanium alloy fabricated by LPBF.It is hypothesized that whilst both low-angle and high-angle grain boundaries are beneficial to the strength,high-angle grain boundary can simultaneously improve the ductility of materi-als.To test this strategy,a Ti-5Cu(wt.%)alloy is selected to compare against pure titanium and Ti-6Al-4V at the same laser processing conditions.EBSD,TEM and XRD analysis show that the as-fabricated LPBF Ti-5Cu alloy is comprised of partially tempered martensite with extraordinarily high number density of both high-angle and low-angle grain boundaries as well as low dislocation density.Such microstructure enables a high tensile strength of 940-1020 MPa,which is at a similar level as LPBF Ti-6Al-4V,and an excellent elongation of 13%-16%,twice as much as that of LPBF Ti-6Al-4V.The mechanism of microstruc-ture refinement in LPBF Ti-5Cu at different levels from prior-βgrains,martensitic packets,blocks to laths is also discussed.展开更多
In the present work, forced convection heat transfer in plate channels filled with metallic or non metallic particles (packed beds) or sintered porous media is simulated numerically using a thermal non equilibrium...In the present work, forced convection heat transfer in plate channels filled with metallic or non metallic particles (packed beds) or sintered porous media is simulated numerically using a thermal non equilibrium model. The numerical simulation results are compared with experimental data. The difference between convection heat transfer in packed beds and in sintered porous media and the effects of the boundary condition assumptions are investigated. The results show that the numerical simulation of convection heat transfer of air or water in packed beds using the local thermal non equilibrium model and the variable porosity model agrees well with the experimental data. The convection heat transfer coefficient in sintered porous media is much higher than that in packed beds. In the numerical simulation of convection heat transfer in sintered porous media, the boundary conditions on the wall should be that the particle temperatures are equal to the fluid temperature.展开更多
It is important to investigate the coalbed methane reservoir boundaries for the classification, exploration, and development of the coalbed methane reservoir. Based on the investigation of the typical coalbed methane ...It is important to investigate the coalbed methane reservoir boundaries for the classification, exploration, and development of the coalbed methane reservoir. Based on the investigation of the typical coalbed methane reservoirs in the world, the boundaries can be divided into four types: hydrodynamic boundary, air altered boundary, permeability boundary, and fault boundary. Hydrodynamic and air altered boundaries are ubiquitous boundaries for every coalbed methane reservoir. The four types of the fault sealing mechanism in the petroleum geological investigation (diagen- esis, clay smear, juxtaposition and cataclasis) are applied to the fault boundary of the coalbed methane reservoir. The sealing mechanism of the open fault boundary is the same with that of the hydrodynamic sealing boundary. The sealing mechanism of the permeability boundary is firstly classified into capillary pressure sealing and hydrocarbon concentration sealing. There are different controlling boundaries in coalbed methane reservoirs that are in different geological backgrounds. Therefore, the coalbed methane reservoir is diversiform.展开更多
In accordance with the characteristics of the rectangular prismatic channel,the flow in the channel was divided into two parts, the bed part and the wall part. On the basis ofgeneral principles of mechanics, the area ...In accordance with the characteristics of the rectangular prismatic channel,the flow in the channel was divided into two parts, the bed part and the wall part. On the basis ofgeneral principles of mechanics, the area relation between the bed part and the wall part was workedout. A formula for determining the shear acting on the bed and the walls in rectangular channelswas derived, which has a simple form and is only related to the ratio of the breadth to the depth.The difference between the calculated value with the presented formula and the data published wasillustrated to be less than that with other, formulas, which shows that the formula is reasonableand can model the flow in the rectangular prismatic channel with higher accuracy and reliability.展开更多
Coastal salt marshes represent an important coastal wetland system. In order to tmderstand the differences between boundary layer parameters of vegetated and unvegetated areas, as well as the mechanisms of sediment tr...Coastal salt marshes represent an important coastal wetland system. In order to tmderstand the differences between boundary layer parameters of vegetated and unvegetated areas, as well as the mechanisms of sediment transport, several electromagnetic current meters （AEM HR, products of Alec Electronics Co. Ltd.） were deployed in coastal wetlands in Quanzhou Bay, China, to measure current velocity. During the low tide phase, the surficial sediment was collected at 10 m intervals. In situ measurements show that the current velocities on the bare flat were much higher than those in the Spartina alterniflora marsh. Current velocity also varied with distance from marsh edge and plant canopy height and diameter. Around 63% of the velocity profiles in the tidal creek can be described by a logarithmic equation. Over the bare flat and Spartina alterniflora marsh, a logarithmic profile almost occurs during the flood tide phase. Sediment analysis shows that mean grain size was 6.7 Ф along the marsh edge, and surface sediments were transported from bare fiat to marsh; the tidal creeks may change this sediment transport pattern. The hydrodynamics at early flood tide and late ebb tide phases determined the net transport direction within the study area.展开更多
Ⅰ. INTRODUCTION It is well-known that when the flow enters the open-channel, the boundary layer was formed. Furthermore, with the development of boundary layer, a uniform open-channel flow was formed. In the case of ...Ⅰ. INTRODUCTION It is well-known that when the flow enters the open-channel, the boundary layer was formed. Furthermore, with the development of boundary layer, a uniform open-channel flow was formed. In the case of uniform open-channel flow, the temporal mean and turbulent characteristics will not vary again. The distance between the inlet of the testing plate and展开更多
The magnetized fluidized bed(MFB)with Geldart-B particles exhibits many distinct flow regimes depend-ing on the magnetic field intensity(H)and gas velocity(U_(g)).The identification of these regimes was reviewed for t...The magnetized fluidized bed(MFB)with Geldart-B particles exhibits many distinct flow regimes depend-ing on the magnetic field intensity(H)and gas velocity(U_(g)).The identification of these regimes was reviewed for the MFB with magnetizable particles and that with binary admixture of magnetizable and nonmagnetizable particles.Meanwhile,methods for determining the boundaries between two adjacent flow regimes were clarified.The MFB state was found to depend not only on H and Ug but also on their application sequence(i.e.,operation mode)within certain operating zones.The dependence feature arose from that the MFB therein could have different equilibrium states for the same combination of H and Ug.Furthermore,such a polymorphic characteristic of the MFB was revealed to result from the internal friction among the particles that were in unfluidized/packed state.Many of the MFB states were demon-strated to be in metastable equilibrium.Nevertheless,they differed significantly from the metastates well-known in the discipline of physical chemistry,such as supercooling and superheated.In fact,they belonged to the amorphous/glass state.This review will deepen our hydrodynamic understanding of the MFB and further promote its commercial application in the chemical and biochemical industries.展开更多
Based on the pseudo-analytical equation of electromagnetic log for layered formation,an optimal boundary match method is proposed to adaptively truncate the encountered formation structures.An efficient integral metho...Based on the pseudo-analytical equation of electromagnetic log for layered formation,an optimal boundary match method is proposed to adaptively truncate the encountered formation structures.An efficient integral method is put forward to significantly accelerate the convergence of Sommerfeld integral.By asymptotically approximating and subtracting the first reflection/transmission waves from the scattered field,the new Sommerfeld integral method has addressed difficulties encountered by the traditional digital filtering method,such as low computational precision and limited operating range,and realized the acceleration of the computation speed of logging-while-drilling electromagnetic measurements(LWD EM).By making use of the priori information from the offset/pilot wells and interactively adjusting the formation model,the optimum initial guesses of the inversion model is determined in order to predict the nearby formation boundaries.The gradient optimization algorithm is developed and an interactive inversion system for the LWD EM data from the horizontal wells is established.The inverted results of field data demonstrated that the real-time interactive inversion method is capable of providing the accurate boundaries of layers around the wellbore from the LWD EM,and it will benefit the wellbore trajectory optimization and reservoir interpretation.展开更多
A discrete element method(DEM)-computa-tional fluid dynamics(CFD)two-way coupling method was employed to simulate the hydrodynamics in a two-dimensional spouted bed with draft plates.The motion of particles was modele...A discrete element method(DEM)-computa-tional fluid dynamics(CFD)two-way coupling method was employed to simulate the hydrodynamics in a two-dimensional spouted bed with draft plates.The motion of particles was modeled by the DEM and the gas flow was modeled by the Navier-Stokes equation.The interactions between gas and particles were considered using a two-way coupling method.The motion of particles in the spouted bed with complex geometry was solved by com-bining DEM and boundary element method(BEM).The minimal spouted velocity was obtained by the BEM-DEM-CFD simulation and the variation of the flow pat-tern in the bed with different superficial gas velocity was studied.The relationship between the pressure drop of the spouted bed and the superficial gas velocity was achieved from the simulations.The radial profile of the averaged vertical velocities of particles and the profile of the aver-aged void fraction in the spout and the annulus were stat-istically analyzed.The flow characteristics of the gas-solid system in the two-dimensional spouted bed were clearly described by the simulation results.展开更多
基金supported by an ANS grant from the National Research Institute for Agriculture,Food and the Environment(2022).
文摘A new mobile bed heat exchanger is presented in this work which is composed of a flowing granular material in a rotating drum and a cylindrical pipe with potential interest in different energy applications as cooling,heating or heat recovery processes.An optimal design of the device requires a characterisation of the phenomena involved at the interface between the granular flow and the pipe.The process is modelled by the discrete element method and a global classification of the flow patterns around the pipe is presented with respect to the three main control parameters of the problem:the Froude number,the diameter ratio and the relative filling height of the drum.The second part is devoted to the characterisation of the structure of the flow at the interface(velocity field,density field)in particular in a so-called Biflow regime where granular motion occurs above as well as below the pipe which is favourable to transfer by convection.A typical behavior at the interface with the pipe consists of a zone I with high velocities of particles at the top of the pipe,a second zone with quasistatic particles or low velocity particles at the front and at the bottom of the pipe and a last zone ll of depletion of particles at the back of the pipe.The Froude number has a limited effect on the features of this structure on the first layer in the range of Froude numbers considered whereas the relative height is a more determinant parameter to control the relative magnitude of velocities in zone I and zone Il as well as the extent of the depletion zone.This first hydrodynamical characterisation can shed light on the dynamical regimes with improved transfer between the particles and the pipe boundary.
基金funded by the Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)-Project-ID 422037413-TRR 287Gefördert durch die Deutsche Forschungsgemeinschaft(DFG)-Projektnummer 422037413-TRR 287.
文摘The present paper presents an experimental and numerical investigation of the dispersion of the gaseous jet flow and co-flow for the simple unit cell(SUC)and body-centred cubic(BCC)configuration of particles in packed beds.The experimental setup is built in such a way that suitable and simplified boundary conditions are imposed for the corresponding numerical framework,so the simulations can be done under very similar conditions as the experiments.Accordingly,a porous plate is used for the co-flow to achieve the uniform velocity and the fully developed flow is ensured for the jet flow.The SUC and BCC particle beds consist of 3D-printed spheres,and the non-isotropy near the walls is mostly eliminated by placing half-spheres at the channel walls.The flow velocities are analysed directly at the exit of the particle bed for both beds over 36 pores for the SUC configuration and 60 pores for the BCC configuration,for particle Reynolds numbers of 200,300,and 400.Stereo particle image velocimetry is experimentally arranged in such a way that the velocities over the entire region at the exit of the packed bed are obtained instantaneously.The numerical method consists of a state-of-the-art immersed boundary method with adaptive mesh refinement.The paper presents the pore jet structure and velocity field exiting from each pore for the SUC and BCC packed particle beds.The numerical and experimental studies show a good agreement for the SUC configuration for all flow velocities.For the BCC configuration,some differences can be observed in the pore jet flow structure between the simulations and the experiments,but the general flow velocity distribution shows a good overall agreement.The axial velocity is generally higher for the pores located near the centre of the packed bed than for the pores near the wall.In addition,the axial velocities are observed to increase near the peripheral pores of the packed bed.This behaviour is predominant for the BCC configuration as compared to the SUC configuration.The velocities near the per
文摘Ecosystem conservation has become one of the purposes in river management as well as flood mitigation and water resources management, and understanding of river flow and morphology in a stream with vegetation becomes important. Recently 2D depth averaged analysis is familiar even in a stream with vegetation by taking account of form drag due to vegetation. However, the shear stress in vegetated area is not properly described because the resistance law due to bed roughness is not reasonably modified in vegetated area. In this study, we discussed the bed roughness boundary layer in flow with non-submerged vegetation to deduce a reasonable relation between U and u* in vegetated area toward improving the analysis of sediment transport. The results show that the modification of resistance law using by thickness, velocity distribution in that layer was found to bring significant improvement of accurate estimation of shear velocity and subsequently the sediment transport. The proposed modification is improved by 2D depth averaged analysis based on this concept, and its application is certificated through flume experiment.
基金supported by the National Key Re-search and Development Program of China(Nos.2018YFC1106600 and 2016YFC1100600)the LiaoNing Revitalization Talents Program(No.XLYC1807069)+2 种基金the National Natural Science Foundation(Nos.51631009 and 31870954)the Doctoral Scientific Research Founda-tion of Liaoning Province(No.2020BS002)Bintech-IMR R&D Pro-gram(GYY-JSBU-2022-008).
文摘Copper element was added in pure titanium to produce a new biomedical titanium-copper alloy by laser powder bed fusion(LPBF).Addition of copper can eliminate the mismatch of high strength but poor duc-tility problem caused by lathα’martensite,which is the usual microstructure of nearαtitanium alloy fabricated by LPBF.Instead of by the usual trade-offrelationship between strength and ductility,which is a long-standing challenge for martensitic titanium alloys,in this study,we proposed a boundary engineer-ing strategy and aim to synergistically enhance the strength and ductility of martensitic titanium alloy fabricated by LPBF.It is hypothesized that whilst both low-angle and high-angle grain boundaries are beneficial to the strength,high-angle grain boundary can simultaneously improve the ductility of materi-als.To test this strategy,a Ti-5Cu(wt.%)alloy is selected to compare against pure titanium and Ti-6Al-4V at the same laser processing conditions.EBSD,TEM and XRD analysis show that the as-fabricated LPBF Ti-5Cu alloy is comprised of partially tempered martensite with extraordinarily high number density of both high-angle and low-angle grain boundaries as well as low dislocation density.Such microstructure enables a high tensile strength of 940-1020 MPa,which is at a similar level as LPBF Ti-6Al-4V,and an excellent elongation of 13%-16%,twice as much as that of LPBF Ti-6Al-4V.The mechanism of microstruc-ture refinement in LPBF Ti-5Cu at different levels from prior-βgrains,martensitic packets,blocks to laths is also discussed.
基金Supported by the National Outstanding Youth Fundfrom the National Natural Science Foundation of China( No.5 0 0 2 5 617) and the Major State Basic ResearchDevelopment Program( No.G19990 3 3 10 6)
文摘In the present work, forced convection heat transfer in plate channels filled with metallic or non metallic particles (packed beds) or sintered porous media is simulated numerically using a thermal non equilibrium model. The numerical simulation results are compared with experimental data. The difference between convection heat transfer in packed beds and in sintered porous media and the effects of the boundary condition assumptions are investigated. The results show that the numerical simulation of convection heat transfer of air or water in packed beds using the local thermal non equilibrium model and the variable porosity model agrees well with the experimental data. The convection heat transfer coefficient in sintered porous media is much higher than that in packed beds. In the numerical simulation of convection heat transfer in sintered porous media, the boundary conditions on the wall should be that the particle temperatures are equal to the fluid temperature.
文摘It is important to investigate the coalbed methane reservoir boundaries for the classification, exploration, and development of the coalbed methane reservoir. Based on the investigation of the typical coalbed methane reservoirs in the world, the boundaries can be divided into four types: hydrodynamic boundary, air altered boundary, permeability boundary, and fault boundary. Hydrodynamic and air altered boundaries are ubiquitous boundaries for every coalbed methane reservoir. The four types of the fault sealing mechanism in the petroleum geological investigation (diagen- esis, clay smear, juxtaposition and cataclasis) are applied to the fault boundary of the coalbed methane reservoir. The sealing mechanism of the open fault boundary is the same with that of the hydrodynamic sealing boundary. The sealing mechanism of the permeability boundary is firstly classified into capillary pressure sealing and hydrocarbon concentration sealing. There are different controlling boundaries in coalbed methane reservoirs that are in different geological backgrounds. Therefore, the coalbed methane reservoir is diversiform.
文摘In accordance with the characteristics of the rectangular prismatic channel,the flow in the channel was divided into two parts, the bed part and the wall part. On the basis ofgeneral principles of mechanics, the area relation between the bed part and the wall part was workedout. A formula for determining the shear acting on the bed and the walls in rectangular channelswas derived, which has a simple form and is only related to the ratio of the breadth to the depth.The difference between the calculated value with the presented formula and the data published wasillustrated to be less than that with other, formulas, which shows that the formula is reasonableand can model the flow in the rectangular prismatic channel with higher accuracy and reliability.
基金supported by the National Natural Science Foundation of China (Grant Nos. 40606012,40576040 and 41076035)
文摘Coastal salt marshes represent an important coastal wetland system. In order to tmderstand the differences between boundary layer parameters of vegetated and unvegetated areas, as well as the mechanisms of sediment transport, several electromagnetic current meters （AEM HR, products of Alec Electronics Co. Ltd.） were deployed in coastal wetlands in Quanzhou Bay, China, to measure current velocity. During the low tide phase, the surficial sediment was collected at 10 m intervals. In situ measurements show that the current velocities on the bare flat were much higher than those in the Spartina alterniflora marsh. Current velocity also varied with distance from marsh edge and plant canopy height and diameter. Around 63% of the velocity profiles in the tidal creek can be described by a logarithmic equation. Over the bare flat and Spartina alterniflora marsh, a logarithmic profile almost occurs during the flood tide phase. Sediment analysis shows that mean grain size was 6.7 Ф along the marsh edge, and surface sediments were transported from bare fiat to marsh; the tidal creeks may change this sediment transport pattern. The hydrodynamics at early flood tide and late ebb tide phases determined the net transport direction within the study area.
基金Project supported by the National Natural Science Foundation of China
文摘Ⅰ. INTRODUCTION It is well-known that when the flow enters the open-channel, the boundary layer was formed. Furthermore, with the development of boundary layer, a uniform open-channel flow was formed. In the case of uniform open-channel flow, the temporal mean and turbulent characteristics will not vary again. The distance between the inlet of the testing plate and
基金supported by the National Natural Science Foundation of China(grant No.21808232).
文摘The magnetized fluidized bed(MFB)with Geldart-B particles exhibits many distinct flow regimes depend-ing on the magnetic field intensity(H)and gas velocity(U_(g)).The identification of these regimes was reviewed for the MFB with magnetizable particles and that with binary admixture of magnetizable and nonmagnetizable particles.Meanwhile,methods for determining the boundaries between two adjacent flow regimes were clarified.The MFB state was found to depend not only on H and Ug but also on their application sequence(i.e.,operation mode)within certain operating zones.The dependence feature arose from that the MFB therein could have different equilibrium states for the same combination of H and Ug.Furthermore,such a polymorphic characteristic of the MFB was revealed to result from the internal friction among the particles that were in unfluidized/packed state.Many of the MFB states were demon-strated to be in metastable equilibrium.Nevertheless,they differed significantly from the metastates well-known in the discipline of physical chemistry,such as supercooling and superheated.In fact,they belonged to the amorphous/glass state.This review will deepen our hydrodynamic understanding of the MFB and further promote its commercial application in the chemical and biochemical industries.
基金Supported by the National Natural Science Foundation of China(41904109,41974146)National Science and Technology Major Project(2017ZX05019-005)+2 种基金China Postdoctoral Science Foundation(2018M640663)the Shandong Province Postdoctoral Innovation Projects(sdbh20180025)National Key Laboratory of Electromagnetic Environment Projects(6142403200307)。
文摘Based on the pseudo-analytical equation of electromagnetic log for layered formation,an optimal boundary match method is proposed to adaptively truncate the encountered formation structures.An efficient integral method is put forward to significantly accelerate the convergence of Sommerfeld integral.By asymptotically approximating and subtracting the first reflection/transmission waves from the scattered field,the new Sommerfeld integral method has addressed difficulties encountered by the traditional digital filtering method,such as low computational precision and limited operating range,and realized the acceleration of the computation speed of logging-while-drilling electromagnetic measurements(LWD EM).By making use of the priori information from the offset/pilot wells and interactively adjusting the formation model,the optimum initial guesses of the inversion model is determined in order to predict the nearby formation boundaries.The gradient optimization algorithm is developed and an interactive inversion system for the LWD EM data from the horizontal wells is established.The inverted results of field data demonstrated that the real-time interactive inversion method is capable of providing the accurate boundaries of layers around the wellbore from the LWD EM,and it will benefit the wellbore trajectory optimization and reservoir interpretation.
基金This work was financially supported by the National Natural Science Foundation of China(Grant No.20306012)the China Postdoctoral Science Foundation(2005038061).
文摘A discrete element method(DEM)-computa-tional fluid dynamics(CFD)two-way coupling method was employed to simulate the hydrodynamics in a two-dimensional spouted bed with draft plates.The motion of particles was modeled by the DEM and the gas flow was modeled by the Navier-Stokes equation.The interactions between gas and particles were considered using a two-way coupling method.The motion of particles in the spouted bed with complex geometry was solved by com-bining DEM and boundary element method(BEM).The minimal spouted velocity was obtained by the BEM-DEM-CFD simulation and the variation of the flow pat-tern in the bed with different superficial gas velocity was studied.The relationship between the pressure drop of the spouted bed and the superficial gas velocity was achieved from the simulations.The radial profile of the averaged vertical velocities of particles and the profile of the aver-aged void fraction in the spout and the annulus were stat-istically analyzed.The flow characteristics of the gas-solid system in the two-dimensional spouted bed were clearly described by the simulation results.
