The Experts below are selected from a list of 225 Experts worldwide ranked by ideXlab platform
Jeanpaul Giovanangeli - One of the best experts on this subject based on the ideXlab platform.
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air flow structure over short gravity breaking water waves
Boundary-Layer Meteorology, 2008Co-Authors: Nicolas Reul, Hubert Branger, Jeanpaul GiovanangeliAbstract:Despite its importance for momentum and mass transfer across the air-sea interface, the dynamic of the airflow over breaking waves is largely unknown. To fill this gap, velocity and vorticity distributions above short-gravity breaking waves have been measured in a wind-wave tank.A Digital Particle Image velocimetry technique was developed to accomplish these measurements above single breaking waves, propagating in mechanically-generated wave groups and forced by the wind. By varying the wind speed and initial characteristics of the groups, the airflow structure was captured over waves at different stages of the breaking process, and breaking with various intensities.The instantaneous airflow Separated from a sharp breaking crest is very similar to that occurs over the backward facing step. The separation bubbles dynamic is however strongly unsteady: the steeper the wave crest and the larger the Reynolds number based on the crest-height, the higher the Separated-Layer and the farther downwind the reattachment point. Instantaneous flow topology displays specific features of three-dimensional separation patterns. The tangential stress above the wave profile do not exhibits spikes at reattachment but grows progressively downwind from zero at reattachment to a value at the next crest approximately that found at the upwind breaking crest. Static pressure measurements revealed that large pressure drops are generated by vortices in the Separated Layer, as found in Separated flows over solids.This study may provide useful data for theoretical and numerical modeling of the flow and associated phenomena.
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Air Flow Structure Over Short-gravity Breaking Water Waves
Boundary-Layer Meteorology, 2008Co-Authors: Nicolas Reul, Hubert Branger, Jeanpaul GiovanangeliAbstract:Despite its importance for momentum and mass transfer across the air–sea interface, the dynamics of airflow over breaking waves is largely unknown. To fill this gap, velocity and vorticity distributions above short-gravity breaking waves have been measured in a wind-wave tank. A Digital Particle Image velocimetry technique (DPIV) was developed to accomplish these measurements above single breaking waves, propagating in mechanically-generated wave groups and forced by the wind. By varying the wind speed and initial characteristics of the groups, the airflow structure was captured over waves at different stages of the breaking process, and breaking with various intensities. The instantaneous airflow that separates from a sharp breaking crest is very similar to that occurring over a backward facing step. The separation bubble is however strongly unsteady: the steeper the wave crest and the larger the Reynolds number based on the crest-height, the higher the Separated Layer and the farther downwind the reattachment point. Instantaneous flow topology displays specific features of three-dimensional separation patterns. The tangential stress above the wave profile does not exhibit spikes at reattachment but grows progressively downwind from zero at reattachment to a value at the next crest approximately that found at the upwind breaking crest. Static pressure measurements revealed that large pressure falls are generated by vortices in the Separated Layer, as found in Separated flows over solids. This study may provide useful data for theoretical and numerical modelling of the flow and associated phenomena.
Nicolas Reul - One of the best experts on this subject based on the ideXlab platform.
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air flow structure over short gravity breaking water waves
Boundary-Layer Meteorology, 2008Co-Authors: Nicolas Reul, Hubert Branger, Jeanpaul GiovanangeliAbstract:Despite its importance for momentum and mass transfer across the air-sea interface, the dynamic of the airflow over breaking waves is largely unknown. To fill this gap, velocity and vorticity distributions above short-gravity breaking waves have been measured in a wind-wave tank.A Digital Particle Image velocimetry technique was developed to accomplish these measurements above single breaking waves, propagating in mechanically-generated wave groups and forced by the wind. By varying the wind speed and initial characteristics of the groups, the airflow structure was captured over waves at different stages of the breaking process, and breaking with various intensities.The instantaneous airflow Separated from a sharp breaking crest is very similar to that occurs over the backward facing step. The separation bubbles dynamic is however strongly unsteady: the steeper the wave crest and the larger the Reynolds number based on the crest-height, the higher the Separated-Layer and the farther downwind the reattachment point. Instantaneous flow topology displays specific features of three-dimensional separation patterns. The tangential stress above the wave profile do not exhibits spikes at reattachment but grows progressively downwind from zero at reattachment to a value at the next crest approximately that found at the upwind breaking crest. Static pressure measurements revealed that large pressure drops are generated by vortices in the Separated Layer, as found in Separated flows over solids.This study may provide useful data for theoretical and numerical modeling of the flow and associated phenomena.
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Air Flow Structure Over Short-gravity Breaking Water Waves
Boundary-Layer Meteorology, 2008Co-Authors: Nicolas Reul, Hubert Branger, Jeanpaul GiovanangeliAbstract:Despite its importance for momentum and mass transfer across the air–sea interface, the dynamics of airflow over breaking waves is largely unknown. To fill this gap, velocity and vorticity distributions above short-gravity breaking waves have been measured in a wind-wave tank. A Digital Particle Image velocimetry technique (DPIV) was developed to accomplish these measurements above single breaking waves, propagating in mechanically-generated wave groups and forced by the wind. By varying the wind speed and initial characteristics of the groups, the airflow structure was captured over waves at different stages of the breaking process, and breaking with various intensities. The instantaneous airflow that separates from a sharp breaking crest is very similar to that occurring over a backward facing step. The separation bubble is however strongly unsteady: the steeper the wave crest and the larger the Reynolds number based on the crest-height, the higher the Separated Layer and the farther downwind the reattachment point. Instantaneous flow topology displays specific features of three-dimensional separation patterns. The tangential stress above the wave profile does not exhibit spikes at reattachment but grows progressively downwind from zero at reattachment to a value at the next crest approximately that found at the upwind breaking crest. Static pressure measurements revealed that large pressure falls are generated by vortices in the Separated Layer, as found in Separated flows over solids. This study may provide useful data for theoretical and numerical modelling of the flow and associated phenomena.
Hubert Branger - One of the best experts on this subject based on the ideXlab platform.
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air flow structure over short gravity breaking water waves
Boundary-Layer Meteorology, 2008Co-Authors: Nicolas Reul, Hubert Branger, Jeanpaul GiovanangeliAbstract:Despite its importance for momentum and mass transfer across the air-sea interface, the dynamic of the airflow over breaking waves is largely unknown. To fill this gap, velocity and vorticity distributions above short-gravity breaking waves have been measured in a wind-wave tank.A Digital Particle Image velocimetry technique was developed to accomplish these measurements above single breaking waves, propagating in mechanically-generated wave groups and forced by the wind. By varying the wind speed and initial characteristics of the groups, the airflow structure was captured over waves at different stages of the breaking process, and breaking with various intensities.The instantaneous airflow Separated from a sharp breaking crest is very similar to that occurs over the backward facing step. The separation bubbles dynamic is however strongly unsteady: the steeper the wave crest and the larger the Reynolds number based on the crest-height, the higher the Separated-Layer and the farther downwind the reattachment point. Instantaneous flow topology displays specific features of three-dimensional separation patterns. The tangential stress above the wave profile do not exhibits spikes at reattachment but grows progressively downwind from zero at reattachment to a value at the next crest approximately that found at the upwind breaking crest. Static pressure measurements revealed that large pressure drops are generated by vortices in the Separated Layer, as found in Separated flows over solids.This study may provide useful data for theoretical and numerical modeling of the flow and associated phenomena.
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Air Flow Structure Over Short-gravity Breaking Water Waves
Boundary-Layer Meteorology, 2008Co-Authors: Nicolas Reul, Hubert Branger, Jeanpaul GiovanangeliAbstract:Despite its importance for momentum and mass transfer across the air–sea interface, the dynamics of airflow over breaking waves is largely unknown. To fill this gap, velocity and vorticity distributions above short-gravity breaking waves have been measured in a wind-wave tank. A Digital Particle Image velocimetry technique (DPIV) was developed to accomplish these measurements above single breaking waves, propagating in mechanically-generated wave groups and forced by the wind. By varying the wind speed and initial characteristics of the groups, the airflow structure was captured over waves at different stages of the breaking process, and breaking with various intensities. The instantaneous airflow that separates from a sharp breaking crest is very similar to that occurring over a backward facing step. The separation bubble is however strongly unsteady: the steeper the wave crest and the larger the Reynolds number based on the crest-height, the higher the Separated Layer and the farther downwind the reattachment point. Instantaneous flow topology displays specific features of three-dimensional separation patterns. The tangential stress above the wave profile does not exhibit spikes at reattachment but grows progressively downwind from zero at reattachment to a value at the next crest approximately that found at the upwind breaking crest. Static pressure measurements revealed that large pressure falls are generated by vortices in the Separated Layer, as found in Separated flows over solids. This study may provide useful data for theoretical and numerical modelling of the flow and associated phenomena.
Mark F. Tachie - One of the best experts on this subject based on the ideXlab platform.
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Proper Orthogonal Decomposition Analysis of Separated and Reattached Pressure Gradient Turbulent Flows
2009Co-Authors: Mohammad K. Shah, Mark F. TachieAbstract:In this paper, the proper orthogonal decomposition was used to analyze velocity data obtained in turbulent flow downstream of a transverse square rib attached to the lower walls of parallel-walled asymmetric diverging and converging channels. The velocity measurements were obtained using a particle image velocimetry. The proper orthogonal decomposition results demonstrate that the energetic structures in the flow contribute most to Reynolds shear stress and least to transverse normal stress. The implications of these observations to the large-scale anisotropy are discussed. Significant differences are observed in the reconstructed Reynolds stress profiles at the center of the Separated shear Layer and those close to the reattachment point. The results also indicate that contribution of the energetic structures to the Reynolds stresses is higher at the upstream section of the ribs than in the Separated Layer. This was attributed to a more uniform energy distribution among the proper orthogonal decomposition modes in the Separated shear Layer than in the upstream section. The distributions of the mean velocity, mixing length, and eddy viscosity at selected locations were also analyzed. The mixing-length profiles in the inner region of the Separated shear Layer do not follow the well-documented linear profile reported for simple near-wall turbulent flows.
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Proper Orthogonal Decomposition Analysis of Separated and Reattached Pressure Gradient Turbulent Flows
AIAA Journal, 2009Co-Authors: Mohammad K. Shah, Mark F. TachieAbstract:are discussed. Significant differences are observed in the reconstructed Reynolds stress profiles at the center of the Separated shear Layer and those close to the reattachment point. The results also indicate that contribution of the energetic structures to the Reynolds stresses is higher at the upstream section of the ribs than in the Separated Layer. Thiswasattributedtoamoreuniformenergydistributionamongtheproperorthogonaldecompositionmodesinthe Separated shear Layer than in the upstream section. The distributions of the mean velocity, mixing length, and eddy viscosityatselectedlocationswerealsoanalyzed.Themixing-lengthprofilesintheinnerregionoftheSeparatedshear Layer do not follow the well-documented linear profile reported for simple near-wall turbulent flows.
He Liu - One of the best experts on this subject based on the ideXlab platform.
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connotation application and prospect of the fourth generation Separated Layer water injection technology
Petroleum Exploration and Development, 2017Co-Authors: He Liu, Xiaohan Pei, Fuchao Sun, Deli Jia, Tong GuoAbstract:Abstract The fourth-generation Separated Layer water injection technology was studied aiming at problems existing in current Separated Layer water-flooding technologies and production requirements. This paper discussed the connotation, core tool and key technologies, analyzed field application and prospected further development. The connotation is to realize digital real-time monitoring on single-well Separated Layer pressure and injection rate of injectors, network informationization of injection performance monitoring of blocks and reservoirs, and integrated reservoir and production engineering by combining injection program design and optimization with real-time adjustment of down hole Separated Layer water injection. An integrated water distributor, a core tool for this technology, and some key technologies including interval flow rate detection and injection allocation adjustment were developed. Moreover, this new technology was piloted in blocks and achieved expected results. In order to meet production requirements, it is necessary to keep research on key technologies, such as downhole interval flow rate detection, wellbore wireless communication, downhole self-power generation and vulnerable components fishing. In addition, this technology shall be properly combined with reservoir engineering, thereby developing a systematical and complete fourth-generation Separated Layer water injection technology that can underpin water flooding development sustainably.
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Connotation, application and prospect of the fourth-generation Separated Layer water injection technology
KeAi Communications Co. Ltd., 2017Co-Authors: He Liu, Xiaohan Pei, Fuchao Sun, Deli Jia, Tong GuoAbstract:The fourth-generation Separated Layer water injection technology was studied aiming at problems existing in current Separated Layer water-flooding technologies and production requirements. This paper discussed the connotation, core tool and key technologies, analyzed field application and prospected further development. The connotation is to realize digital real-time monitoring on single-well Separated Layer pressure and injection rate of injectors, network informationization of injection performance monitoring of blocks and reservoirs, and integrated reservoir and production engineering by combining injection program design and optimization with real-time adjustment of down hole Separated Layer water injection. An integrated water distributor, a core tool for this technology, and some key technologies including interval flow rate detection and injection allocation adjustment were developed. Moreover, this new technology was piloted in blocks and achieved expected results. In order to meet production requirements, it is necessary to keep research on key technologies, such as downhole interval flow rate detection, wellbore wireless communication, downhole self-power generation and vulnerable components fishing. In addition, this technology shall be properly combined with reservoir engineering, thereby developing a systematical and complete fourth-generation Separated Layer water injection technology that can underpin water flooding development sustainably. Key words: water flooding development, reservoir engineering, Separated Layer water injection, qualification rate of water injection, cable measuring and adjusting, flow rate measurin
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a new concentric zonal water injection technique for highly deviated wells
Petroleum Exploration and Development, 2015Co-Authors: He Liu, Xiaohan Pei, Fuchao Sun, Guohua Xiao, H U Huili, Haitao Geng, L I LiangchuanAbstract:Abstract Existing eccentric zonal water injection techniques cannot meet the requirements of Separated Layer water injection, testing and adjustment in highly-deviated wells, because of their low fishing success rate of down-hole nozzles, low efficiency of connection between instruments and nozzles, and low precision of zonal flow rate test. A new concentric zonal water injection technique is proposed for highly-deviated wells. This technique adopts concentric testing and adjustment, i.e., the test instrument is concentrically connected with the down-hole regulator, with high success rate of connection. The down-hole regulator uses bridge-type channel to effectively eliminate inter-Layer interference and thereby improving testing and adjustment efficiency. Water flow rate is adjusted with an eccentric valve, which features small loss in full-off state, small adjustment torque and easier water adjustment. This technique is functional for both collected flow test and non-collected flow test, so it is workable for low flow rate test. It can achieve packer seal test on line by cable, the status of seal balls can be monitored and all seal test operations can be completed in one trip. This technique can obtain flow rate, pressure, temperature and other parameters of any Layer on line and automatic testing and adjustment of injection allocation rate, without fishing, significantly improving testing and adjustment efficiency. Until now, this technique has been tested in 11 wells (maximum well deviation of 55°), with tested flow rate error of less than 5%, and three-Layer seal check and adjustment time of less than one day. Compared with the existing techniques, this new technique has advantages such as high testing and adjustment efficiency, high precision and low cost.
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current status and trend of Separated Layer water flooding in china
Petroleum Exploration and Development, 2013Co-Authors: He Liu, Xiaohan Pei, Kai Luo, Fuchao Sun, Lichen Zheng, Qinghai YangAbstract:Abstract Separated Layer water injection is one of the crucial means to keep long-term high and stable production of oilfield. “Bridge eccentricity + steel cable measuring and adjustment” has come into being as the principal water flooding technology, which, with improving adaptability, can meet the need of conventional water injection wells. As the water flooding fields enter high water-cut period, sand control for water injectors, Separated Layer flowrate test at low injection rate, high pressure and high temperature water injection, Separated Layer water injection for high-inclination wells and Separated Layer water injection monitoring and control will be the developing trend, directing water flooding towards automatization, intelligence and integration to meet the requirements of water injection under different reservoir and well type conditions for the purpose of ensuring efficient oil field development. Currently periodic progress have been made in downhole wireless communication, flowrate monitoring, nozzle dynamic adjustment, etc, forming the theoretical basis for automatic water flooding.
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An Innovative PCP Logging Technique for the Separated Layer Production Wells
All Days, 2010Co-Authors: He Liu, Fengshan Wang, Guochen Shi, Gang Cao, Tao JiangAbstract:Abstract In the past 50 years, the oil production of Daqing Oilfield has maintained 50 million tons (near 350 million bbls) per year for 27 years. To date, Daqing Oilfield is still the largest continental oilfield in China. Separated Layer development technology is one of the key techniques contributed to this great achievement. In order to monitor dynamic performance of Separated Layer production, it was necessary to implement logging technique periodically in a large number of selected injectors and producers. Due to the limit of annulus size is too small for sensor to be run into down hole of progressing cavity pump (PCP) wells, traditional PCP system design couldn’t meet the requirement of well logging for Separated Layer production. Since separate Layer development technology is more and more popular in oilfield development, PCP logging technique has become a bottleneck issue which limited PCP application in larger scale. This paper presented an innovative design for logging technique in PCP wells. In this design, a unique drive head design was developed as well as several special downhole tools which applied the path for sensor and wire to be run into the appointed place. Till the end of 2009, this technique has been applied in more than 200 PCP wells in Daqing Oilfield. The operation was simple and safety, the successful ratio was 95%. This technique could also be applied in other conditions which has a brilliant future.
