In the petroleum engineering and chemical industries, fluids engaging in displacement often have non-Newtonian properties, even though many former studies assume constant viscosities in the defending fluid. In this study, the computational fluid dynamics approach was performed in a two-dimensional model with uniformly distributed disks. This arrangement helps reveal the phenomenon and mechanics of how non-Newtonian characteristics of defending fluid affect two-phase displacement in porous media. Both global (in the whole medium) and regional (in the pore throat) studies revealed that shear-thinning makes capillary force and the pressure in the invading fluid decisive and leads to a uniform pattern. Meanwhile, the shear-thickening causes fingering due to the pressure drop in the defending fluid that becomes decisive. Cases of increasing injection rates were investigated to verify their ability to improve efficiency. The results verified that increased injection rates are effective in shear-thinning cases but energy-intensive when it comes to costs in shear-thickening cases. Finally, the viscosity ratio and capillary number (M-Ca) diagram were extended by plotting non-Newtonian cases as lines to consider viscosity variation. An estimation method was presented, which calculates the characteristic viscosity and locates non-Newtonian cases on an M-Ca diagram. This work can serve as a reference for enhanced oil recovery method development and microfluidic manipulation.
{"title":"Numerical pore-scale investigation of two-phase displacement with non-Newtonian defending fluid","authors":"Wenyuan Wang, Pengfei Liu, Chen Zhou, Bate Bate, Yunmin Chen","doi":"10.1063/5.0223061","DOIUrl":"https://doi.org/10.1063/5.0223061","url":null,"abstract":"In the petroleum engineering and chemical industries, fluids engaging in displacement often have non-Newtonian properties, even though many former studies assume constant viscosities in the defending fluid. In this study, the computational fluid dynamics approach was performed in a two-dimensional model with uniformly distributed disks. This arrangement helps reveal the phenomenon and mechanics of how non-Newtonian characteristics of defending fluid affect two-phase displacement in porous media. Both global (in the whole medium) and regional (in the pore throat) studies revealed that shear-thinning makes capillary force and the pressure in the invading fluid decisive and leads to a uniform pattern. Meanwhile, the shear-thickening causes fingering due to the pressure drop in the defending fluid that becomes decisive. Cases of increasing injection rates were investigated to verify their ability to improve efficiency. The results verified that increased injection rates are effective in shear-thinning cases but energy-intensive when it comes to costs in shear-thickening cases. Finally, the viscosity ratio and capillary number (M-Ca) diagram were extended by plotting non-Newtonian cases as lines to consider viscosity variation. An estimation method was presented, which calculates the characteristic viscosity and locates non-Newtonian cases on an M-Ca diagram. This work can serve as a reference for enhanced oil recovery method development and microfluidic manipulation.","PeriodicalId":20066,"journal":{"name":"Physics of Fluids","volume":null,"pages":null},"PeriodicalIF":4.6,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142218327","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Anthony Man, Mohammad Jadidi, Amir Keshmiri, Hujun Yin, Yasser Mahmoudi
Recent growing interest in using machine learning for turbulence modeling has led to many proposed data-driven turbulence models in the literature. However, most of these models have not been developed with overcoming non-unique mapping (NUM) in mind, which is a significant source of training and prediction error. Only NUM caused by one-dimensional channel flow data has been well studied in the literature, despite most data-driven models having been trained on two-dimensional flow data. The present work aims to be the first detailed investigation on NUM caused by two-dimensional flows. A method for quantifying NUM is proposed and demonstrated on data from a flow over periodic hills and an impinging jet. The former is a wall-bounded separated flow, and the latter is a shear flow containing stagnation and recirculation. This work confirms that data from two-dimensional flows can cause NUM in data-driven turbulence models with the commonly used invariant inputs. This finding was verified with both cases, which contain different flow phenomena, hence showing that NUM is not limited to specific flow physics. Furthermore, the proposed method revealed that regions containing low strain and rotation or near pure shear cause the majority of NUM in both cases—approximately 76% and 89% in the flow over periodic hills and impinging jet, respectively. These results led to viscosity ratio being selected as a supplementary input variable (SIV), demonstrating that SIVs can reduce NUM caused by data from two-dimensional flows and subsequently improve the accuracy of tensor-basis machine learning models for turbulence modeling.
最近，人们对使用机器学习进行湍流建模的兴趣日益浓厚，因此在文献中提出了许多数据驱动的湍流模型。然而，这些模型大多没有考虑克服非唯一映射（NUM）问题，而非唯一映射是训练和预测误差的重要来源。尽管大多数数据驱动模型都是在二维水流数据上进行训练的，但文献中只对一维水道水流数据引起的非唯一映射进行了深入研究。本研究旨在首次详细调查二维流动造成的 NUM。本文提出了一种量化 NUM 的方法，并在周期性山丘上的流动和冲击射流的数据上进行了演示。前者是壁界分离流，后者是包含停滞和再循环的剪切流。这项工作证实，二维流的数据会导致数据驱动湍流模型中的 NUM，而这些数据是常用的不变输入。这一发现在包含不同流动现象的两种情况下都得到了验证，从而表明 NUM 并不局限于特定的流动物理。此外，所提出的方法还显示，在两种情况下，包含低应变和旋转或接近纯剪切的区域会导致大部分 NUM--在周期性山丘上的流动和冲击射流中分别约为 76% 和 89%。这些结果促使粘度比被选为补充输入变量（SIV），证明了 SIV 可以减少二维流动数据引起的 NUM，从而提高用于湍流建模的张量基础机器学习模型的准确性。
{"title":"Non-unique machine learning mapping in data-driven Reynolds-averaged turbulence models","authors":"Anthony Man, Mohammad Jadidi, Amir Keshmiri, Hujun Yin, Yasser Mahmoudi","doi":"10.1063/5.0220444","DOIUrl":"https://doi.org/10.1063/5.0220444","url":null,"abstract":"Recent growing interest in using machine learning for turbulence modeling has led to many proposed data-driven turbulence models in the literature. However, most of these models have not been developed with overcoming non-unique mapping (NUM) in mind, which is a significant source of training and prediction error. Only NUM caused by one-dimensional channel flow data has been well studied in the literature, despite most data-driven models having been trained on two-dimensional flow data. The present work aims to be the first detailed investigation on NUM caused by two-dimensional flows. A method for quantifying NUM is proposed and demonstrated on data from a flow over periodic hills and an impinging jet. The former is a wall-bounded separated flow, and the latter is a shear flow containing stagnation and recirculation. This work confirms that data from two-dimensional flows can cause NUM in data-driven turbulence models with the commonly used invariant inputs. This finding was verified with both cases, which contain different flow phenomena, hence showing that NUM is not limited to specific flow physics. Furthermore, the proposed method revealed that regions containing low strain and rotation or near pure shear cause the majority of NUM in both cases—approximately 76% and 89% in the flow over periodic hills and impinging jet, respectively. These results led to viscosity ratio being selected as a supplementary input variable (SIV), demonstrating that SIVs can reduce NUM caused by data from two-dimensional flows and subsequently improve the accuracy of tensor-basis machine learning models for turbulence modeling.","PeriodicalId":20066,"journal":{"name":"Physics of Fluids","volume":null,"pages":null},"PeriodicalIF":4.6,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142218324","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yuanying Du, Hairong Zhao, Hong Ji, Wenshan Wang, Hongbo Wang, Feiqin Xu
Aiming at the key problems such as serious friction and wear and large leakage of aviation piston pumps operating under high-speed and high-pressure harsh conditions, the lubrication characteristics of aviation plunger pumps are studied in this paper. In order to improve the lubrication performance of the plunger pump, as well as its working efficiency and service life, the equations of pressure, the thickness, and the leakage of the plunger pair oil film under the combined actions of viscosity temperature and pressure under pressure flow, shear flow, and cylinder elastic deformation are established. The finite difference method is used to analyze the lubrication characteristics and the leakage of the plunger pair under these four different conditions: considering, respectively, the effect of viscosity temperature and pressure, only considering the effect of viscosity temperature or viscosity pressure, without considering the effect of viscosity temperature and viscosity pressure. As a result, coupled by the effects of viscosity temperature and viscosity pressure, when the temperature increases from 20 to 60 °C, the oil film pressure increases, and the thickness decreases faster. When the temperature increases from 60 to 120 °C, the oil film pressure increases and the thickness decreases slower When the contact length of the plunger pair increases from 17 to 37 mm, the leakage ratio decreases more rapidly, and when it is greater than 37 mm, it decreases more slowly. The following conclusions were obtained: the viscosity of lubricating fluid is greatly affected by temperature and pressure. The viscosity decreases and increases hyperbolically with the increase in temperature and pressure, the maximum oil film pressure when considering the effect of viscosity temperature and pressure was significantly greater than that without considering the viscosity temperature and pressure, and the minimum oil film thickness was much smaller than that without considering the viscosity temperature and pressure. The leakage curve when considering the viscosity temperature and pressure effect was obviously different from when only considering a single factor or not considering the viscosity temperature and pressure effect. The magnitude of leakage in the four cases is: considering the viscosity temperature effect, considering the viscosity temperature and pressure effect, not considering the viscosity temperature and pressure effect, and considering the viscosity pressure effect. This study can provide a reference for the accurate theoretical design and safe and stable operation of the plunger pair in the plunger pump.
针对航空柱塞泵在高速、高压等恶劣工况下运行时摩擦磨损严重、泄漏量大等关键问题，本文对航空柱塞泵的润滑特性进行了研究。为了改善柱塞泵的润滑性能，提高其工作效率和使用寿命，建立了柱塞副油膜在压力流、剪切流和油缸弹性变形作用下，在粘度温度和压力共同作用下的压力、厚度和泄漏量方程。采用有限差分法分析了分别考虑粘温和粘压影响、只考虑粘温或粘压影响、不考虑粘温和粘压影响这四种不同条件下柱塞副的润滑特性和泄漏情况。结果，在粘温和粘压的影响下，当温度从 20 ℃ 升至 60 ℃ 时，油膜压力增加，厚度下降较快。当温度从 60 ℃ 升至 120 ℃ 时，油膜压力增加，厚度减小得较慢。当柱塞对的接触长度从 17 mm 增加到 37 mm 时，泄漏率减小得更快，当大于 37 mm 时，泄漏率减小得更慢。得出以下结论：润滑油的粘度受温度和压力的影响很大。随着温度和压力的升高，粘度呈双曲线减小和增大，考虑粘度温度和压力影响时的最大油膜压力明显大于不考虑粘度温度和压力时的最大油膜压力，最小油膜厚度远小于不考虑粘度温度和压力时的最小油膜厚度。考虑粘度温度和压力影响时的泄漏曲线与只考虑单一因素或不考虑粘度温度和压力影响时的泄漏曲线明显不同。四种情况下的泄漏量分别为：考虑粘温效应、考虑粘温和粘压效应、不考虑粘温和粘压效应、考虑粘压效应。本研究可为柱塞泵中柱塞副的精确理论设计和安全稳定运行提供参考。
{"title":"Research on lubrication mechanism of plunger pair considering viscosity temperature and pressure effect","authors":"Yuanying Du, Hairong Zhao, Hong Ji, Wenshan Wang, Hongbo Wang, Feiqin Xu","doi":"10.1063/5.0227691","DOIUrl":"https://doi.org/10.1063/5.0227691","url":null,"abstract":"Aiming at the key problems such as serious friction and wear and large leakage of aviation piston pumps operating under high-speed and high-pressure harsh conditions, the lubrication characteristics of aviation plunger pumps are studied in this paper. In order to improve the lubrication performance of the plunger pump, as well as its working efficiency and service life, the equations of pressure, the thickness, and the leakage of the plunger pair oil film under the combined actions of viscosity temperature and pressure under pressure flow, shear flow, and cylinder elastic deformation are established. The finite difference method is used to analyze the lubrication characteristics and the leakage of the plunger pair under these four different conditions: considering, respectively, the effect of viscosity temperature and pressure, only considering the effect of viscosity temperature or viscosity pressure, without considering the effect of viscosity temperature and viscosity pressure. As a result, coupled by the effects of viscosity temperature and viscosity pressure, when the temperature increases from 20 to 60 °C, the oil film pressure increases, and the thickness decreases faster. When the temperature increases from 60 to 120 °C, the oil film pressure increases and the thickness decreases slower When the contact length of the plunger pair increases from 17 to 37 mm, the leakage ratio decreases more rapidly, and when it is greater than 37 mm, it decreases more slowly. The following conclusions were obtained: the viscosity of lubricating fluid is greatly affected by temperature and pressure. The viscosity decreases and increases hyperbolically with the increase in temperature and pressure, the maximum oil film pressure when considering the effect of viscosity temperature and pressure was significantly greater than that without considering the viscosity temperature and pressure, and the minimum oil film thickness was much smaller than that without considering the viscosity temperature and pressure. The leakage curve when considering the viscosity temperature and pressure effect was obviously different from when only considering a single factor or not considering the viscosity temperature and pressure effect. The magnitude of leakage in the four cases is: considering the viscosity temperature effect, considering the viscosity temperature and pressure effect, not considering the viscosity temperature and pressure effect, and considering the viscosity pressure effect. This study can provide a reference for the accurate theoretical design and safe and stable operation of the plunger pair in the plunger pump.","PeriodicalId":20066,"journal":{"name":"Physics of Fluids","volume":null,"pages":null},"PeriodicalIF":4.6,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142218322","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xuesen Chu, Feng Zhao, Zhengdao Wang, Yuehong Qian, Guangwen Yang
This study investigates the propagation of sound waves within deep-sea low-sound-speed channels using the lattice Boltzmann method, with a key focus on the influence of depth-dependent sound speed on wave propagation. The depth-variable sound speed condition is realized through the incorporation of an external force proportional to the density gradient. After the model verification, investigations into the two-dimensional spreading of sound sources reveal that the depth-dependent sound speed curves the wave propagation. When source depths differing from the low-sound-speed channel, wave paths deviate due to contrasting speeds above and below. When the sound source is situated within the low-sound-speed channel, waves exhibit converging patterns. The simulations also detail the total reflection behavior of sound waves. When the incident angle falls exceeds the critical angle, the waves remain intact within the low-sound-speed channel, thereby enabling the preservation of high amplitude acoustic signals even at remote locations. The subsequent simulations of sound wave propagation around obstacles demonstrate that the low-sound-speed channel also exhibits better signal transmission capabilities in the presence of obstacles. In a uniform sound speed environment, acoustic wave propagation around a submarine exhibits a symmetric pattern. By contrast, under depth-evolving speed conditions, submarines operating at various depths manifest distinct propagation characteristics, such as asymmetric wave propagation during shallow diving, as well as wave attenuation or even silencing when cruising within low-sound-speed channels. These findings underscore the profound implications of depth-evolving sound speed on underwater acoustic signal detection and transmission.
{"title":"Acoustic wave propagation in depth-evolving sound-speed field using the lattice Boltzmann method","authors":"Xuesen Chu, Feng Zhao, Zhengdao Wang, Yuehong Qian, Guangwen Yang","doi":"10.1063/5.0222202","DOIUrl":"https://doi.org/10.1063/5.0222202","url":null,"abstract":"This study investigates the propagation of sound waves within deep-sea low-sound-speed channels using the lattice Boltzmann method, with a key focus on the influence of depth-dependent sound speed on wave propagation. The depth-variable sound speed condition is realized through the incorporation of an external force proportional to the density gradient. After the model verification, investigations into the two-dimensional spreading of sound sources reveal that the depth-dependent sound speed curves the wave propagation. When source depths differing from the low-sound-speed channel, wave paths deviate due to contrasting speeds above and below. When the sound source is situated within the low-sound-speed channel, waves exhibit converging patterns. The simulations also detail the total reflection behavior of sound waves. When the incident angle falls exceeds the critical angle, the waves remain intact within the low-sound-speed channel, thereby enabling the preservation of high amplitude acoustic signals even at remote locations. The subsequent simulations of sound wave propagation around obstacles demonstrate that the low-sound-speed channel also exhibits better signal transmission capabilities in the presence of obstacles. In a uniform sound speed environment, acoustic wave propagation around a submarine exhibits a symmetric pattern. By contrast, under depth-evolving speed conditions, submarines operating at various depths manifest distinct propagation characteristics, such as asymmetric wave propagation during shallow diving, as well as wave attenuation or even silencing when cruising within low-sound-speed channels. These findings underscore the profound implications of depth-evolving sound speed on underwater acoustic signal detection and transmission.","PeriodicalId":20066,"journal":{"name":"Physics of Fluids","volume":null,"pages":null},"PeriodicalIF":4.6,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142218318","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper presents a very large eddy simulation analysis of the unsteady flow in the pre-stall to stall transition process of an axial-flow pump, with the aim to elucidate the spatiotemporal evolution of large-scale flow structures during the performance breakdown of the pump. The transient flow is investigated utilizing a time-dependent flow rate computation scheme. The results demonstrate that, as the flow rate is dynamically reduced, the reduction in pump head is found lags behind the reduction in flow rate by approximately 15 impeller revolutions. The leading edge separation on the blade suction side (SS) evolves into a leading edge separation vortex (LSV) in conjunction with the dynamic reduction in flow rate. The attached flow on the SS in the vicinity of the hub and blade trailing edge squeezes the mainstream outwards, resulting in the formation of a cross passage vortex (CPV) on the tip side of the passage. The combined effect of the LSV, CPV, and tip-clearance flow induces a penetrating upstream flow in the tip region of the impeller, which gives rise to a swirling backflow within the inlet pipe. At stall, the CPV is stably attached to the SS and extends upstream of the leading edge of the neighboring blade. Furthermore, a trailing edge backflow is observed near the junction of the blade trailing edge and the hub, and it collides with the inflow near the hub, resulting in the formation of a hub-attached vortex.
本文对轴流泵从失速前到失速过渡过程中的非稳态流动进行了超大涡模拟分析，旨在阐明泵性能故障期间大尺度流动结构的时空演变。利用随时间变化的流速计算方案对瞬态流动进行了研究。结果表明，随着流速的动态降低，发现泵扬程的降低滞后于流速的降低约 15 转。叶片吸入侧（SS）的前缘分离会随着流速的动态降低而演变成前缘分离涡流（LSV）。轮毂和叶片后缘附近 SS 上的附着流向外挤压主流，从而在通道顶端形成交叉通道漩涡 (CPV)。在 LSV、CPV 和叶尖清流的共同作用下，叶轮的叶尖区域会产生穿透性上游流，从而在进气管道内形成漩涡回流。失速时，CPV 稳定地附着在 SS 上，并向邻近叶片前缘的上游延伸。此外，在叶片后缘和轮毂交界处附近观察到后缘回流，它与轮毂附近的流入流碰撞，形成轮毂附着漩涡。
{"title":"Evolution of large-scale flow structures in an axial-flow pump during performance breakdown","authors":"Lei Wang, Shaoxuan Kang, Yaojun Li, Weisheng Chen","doi":"10.1063/5.0229228","DOIUrl":"https://doi.org/10.1063/5.0229228","url":null,"abstract":"This paper presents a very large eddy simulation analysis of the unsteady flow in the pre-stall to stall transition process of an axial-flow pump, with the aim to elucidate the spatiotemporal evolution of large-scale flow structures during the performance breakdown of the pump. The transient flow is investigated utilizing a time-dependent flow rate computation scheme. The results demonstrate that, as the flow rate is dynamically reduced, the reduction in pump head is found lags behind the reduction in flow rate by approximately 15 impeller revolutions. The leading edge separation on the blade suction side (SS) evolves into a leading edge separation vortex (LSV) in conjunction with the dynamic reduction in flow rate. The attached flow on the SS in the vicinity of the hub and blade trailing edge squeezes the mainstream outwards, resulting in the formation of a cross passage vortex (CPV) on the tip side of the passage. The combined effect of the LSV, CPV, and tip-clearance flow induces a penetrating upstream flow in the tip region of the impeller, which gives rise to a swirling backflow within the inlet pipe. At stall, the CPV is stably attached to the SS and extends upstream of the leading edge of the neighboring blade. Furthermore, a trailing edge backflow is observed near the junction of the blade trailing edge and the hub, and it collides with the inflow near the hub, resulting in the formation of a hub-attached vortex.","PeriodicalId":20066,"journal":{"name":"Physics of Fluids","volume":null,"pages":null},"PeriodicalIF":4.6,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142218386","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Accurate daily oil production forecasting is essential for efficient reservoir management and investment strategy. Forecasting oil production in enhanced oil recovery (EOR) and conformance-dominated fields is a complex process due to the nonlinear, voluminous, and often uncertain nature of reservoir parameters and hidden factors. As a result, conventional tools such as decline curve analysis frequently fail to accurately predict daily oil production in conformance-controlled areas. In contrast, machine learning works efficiently for large datasets, even if the parameter values are unknown. The current study employs a Prophet time series forecasting method for five oil production wells in an EOR applied field, but it fails to achieve the desired sweep efficiency. This study compares the results of conventional decline curve analysis (DCA) and popular autoregressive integrated moving average time series forecasting methods with the Prophet model. This is the first attempt to use Prophet for oil well production forecasting, where polymer flooding is used. In all, 60% of the data are used for training, and the remaining 40% are used for testing. The Prophet shows the best performance for all the wells. This study is also the first to handle shut-in data using the Prophet model for oil production. Well-2 achieves the highest accuracy after incorporating shut-in results, with an R2 score of 92%. The result shows that though the DCA performs reasonably well with higher linearity and trend stationary data, Prophet modeling shows superior results than conventional DCA for all EOR applied producing wells.
{"title":"Prophet modeling for oil production forecasting in an enhanced oil recovery field","authors":"H. K. Chavan, R. K. Sinharay","doi":"10.1063/5.0224299","DOIUrl":"https://doi.org/10.1063/5.0224299","url":null,"abstract":"Accurate daily oil production forecasting is essential for efficient reservoir management and investment strategy. Forecasting oil production in enhanced oil recovery (EOR) and conformance-dominated fields is a complex process due to the nonlinear, voluminous, and often uncertain nature of reservoir parameters and hidden factors. As a result, conventional tools such as decline curve analysis frequently fail to accurately predict daily oil production in conformance-controlled areas. In contrast, machine learning works efficiently for large datasets, even if the parameter values are unknown. The current study employs a Prophet time series forecasting method for five oil production wells in an EOR applied field, but it fails to achieve the desired sweep efficiency. This study compares the results of conventional decline curve analysis (DCA) and popular autoregressive integrated moving average time series forecasting methods with the Prophet model. This is the first attempt to use Prophet for oil well production forecasting, where polymer flooding is used. In all, 60% of the data are used for training, and the remaining 40% are used for testing. The Prophet shows the best performance for all the wells. This study is also the first to handle shut-in data using the Prophet model for oil production. Well-2 achieves the highest accuracy after incorporating shut-in results, with an R2 score of 92%. The result shows that though the DCA performs reasonably well with higher linearity and trend stationary data, Prophet modeling shows superior results than conventional DCA for all EOR applied producing wells.","PeriodicalId":20066,"journal":{"name":"Physics of Fluids","volume":null,"pages":null},"PeriodicalIF":4.6,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142218325","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study delves into the dynamics of non-simultaneous droplet impacts on solid substrates, focusing on interactions between identical impacting droplets. Comparisons between non-simultaneous and simultaneous impacts are presented to understand the phenomena comprehensively. An in-house-built microcontroller-based droplet generator releases two equal-sized droplets on demand, allowing for simultaneous or non-simultaneous impacts. The interaction between impacting droplets generates an uprising sheet, whose characteristics vary with time lag between impacts, impact Weber number, and inter-droplet spacing. The evolution of central sheet characteristics, lamellae spreading dynamics, splashing mechanism, and secondary atomization is evaluated. Findings reveal that central sheet morphology varies with the time lag between impacts, transitioning from a two-dimensional (2D) “semilunar” sheet (vertical or inclined) with a linear base to a three-dimensional (3D) sheet with a curved base, increasing the probability of secondary atomization. The temporal evolution of the central sheet position, height, and inclination angle is governed by the momentum of spreading lamellae. A novel scaling law for maximum sheet extension and a theoretical expression for surface liquid spread are proposed, consistent with the measurements. The characteristics of secondary droplets generated during non-simultaneous impacts are similar to those from simultaneous impacts, with the size of the secondary droplets being one order of magnitude larger than those expected from isolated single-droplet impacts.
{"title":"Non-simultaneous impact of droplet pairs on solid surfaces","authors":"Anjan Goswami, Yannis Hardalupas","doi":"10.1063/5.0225562","DOIUrl":"https://doi.org/10.1063/5.0225562","url":null,"abstract":"This study delves into the dynamics of non-simultaneous droplet impacts on solid substrates, focusing on interactions between identical impacting droplets. Comparisons between non-simultaneous and simultaneous impacts are presented to understand the phenomena comprehensively. An in-house-built microcontroller-based droplet generator releases two equal-sized droplets on demand, allowing for simultaneous or non-simultaneous impacts. The interaction between impacting droplets generates an uprising sheet, whose characteristics vary with time lag between impacts, impact Weber number, and inter-droplet spacing. The evolution of central sheet characteristics, lamellae spreading dynamics, splashing mechanism, and secondary atomization is evaluated. Findings reveal that central sheet morphology varies with the time lag between impacts, transitioning from a two-dimensional (2D) “semilunar” sheet (vertical or inclined) with a linear base to a three-dimensional (3D) sheet with a curved base, increasing the probability of secondary atomization. The temporal evolution of the central sheet position, height, and inclination angle is governed by the momentum of spreading lamellae. A novel scaling law for maximum sheet extension and a theoretical expression for surface liquid spread are proposed, consistent with the measurements. The characteristics of secondary droplets generated during non-simultaneous impacts are similar to those from simultaneous impacts, with the size of the secondary droplets being one order of magnitude larger than those expected from isolated single-droplet impacts.","PeriodicalId":20066,"journal":{"name":"Physics of Fluids","volume":null,"pages":null},"PeriodicalIF":4.6,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142218323","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Longgang Sun, Lei Liu, Zhaoning Wang, Pengcheng Guo, Zhuofei Xu
This study numerically investigates the load reduction effects, on a model Francis turbine, combining cavitation model and structured dynamic grid technique. The results indicate that the vapor volume in the draft tube undergoes two rapid increases and decreases until cavitation ceases. The precessing vortex rope transitions from a strong helical structure to axial contraction as ellipticity increases, ultimately forming a discrete band before disappearing. Initially, vapor volume in the runner increases gradually and linearly, followed by continued growth with a consistent pulsation amplitude. The inter-blade vortex (IBV) first appears at the blade trailing edge and then develops into a complete structure extending from the runner crown to the blade trailing edge, driven by pulsating vapor volume growth. Axial force extracted by the runner changes significantly and correlates closely with variations in the vapor volume in the runner. Flow separation in the runner occurs near the runner crown, forming dual separation lines that enhance IBV formation, which highlights the significant influence of crown-proximal flow separation on IBV development. Regarding energy loss, initial decreases followed by increases are observed in both the draft tube and runner, with draft tube losses consistently exceeding 57.4% and runner losses exceeding 27.1%. Turbulent kinetic energy generation and Reynolds stress are the primary forms of energy dissipation, with high-value regions corresponding to vortex locations, underscoring the substantial role of vortices in energy dissipation. This study provides new insights into the evolution of vortices and energy dissipation characteristics during load reduction in Francis turbines.
{"title":"Temporal-spatial and energy dissipation characteristics of vortex evolutions in Francis turbine during load reduction","authors":"Longgang Sun, Lei Liu, Zhaoning Wang, Pengcheng Guo, Zhuofei Xu","doi":"10.1063/5.0229831","DOIUrl":"https://doi.org/10.1063/5.0229831","url":null,"abstract":"This study numerically investigates the load reduction effects, on a model Francis turbine, combining cavitation model and structured dynamic grid technique. The results indicate that the vapor volume in the draft tube undergoes two rapid increases and decreases until cavitation ceases. The precessing vortex rope transitions from a strong helical structure to axial contraction as ellipticity increases, ultimately forming a discrete band before disappearing. Initially, vapor volume in the runner increases gradually and linearly, followed by continued growth with a consistent pulsation amplitude. The inter-blade vortex (IBV) first appears at the blade trailing edge and then develops into a complete structure extending from the runner crown to the blade trailing edge, driven by pulsating vapor volume growth. Axial force extracted by the runner changes significantly and correlates closely with variations in the vapor volume in the runner. Flow separation in the runner occurs near the runner crown, forming dual separation lines that enhance IBV formation, which highlights the significant influence of crown-proximal flow separation on IBV development. Regarding energy loss, initial decreases followed by increases are observed in both the draft tube and runner, with draft tube losses consistently exceeding 57.4% and runner losses exceeding 27.1%. Turbulent kinetic energy generation and Reynolds stress are the primary forms of energy dissipation, with high-value regions corresponding to vortex locations, underscoring the substantial role of vortices in energy dissipation. This study provides new insights into the evolution of vortices and energy dissipation characteristics during load reduction in Francis turbines.","PeriodicalId":20066,"journal":{"name":"Physics of Fluids","volume":null,"pages":null},"PeriodicalIF":4.6,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142218321","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study combines convolutional neural networks, spatial pyramid pooling, and long short-term memory networks (LSTM) with self-attention (SA) mechanisms (abbreviated as CSAL) to address the problem of production dynamics prediction in tight reservoirs during the CO2 water-alternating-gas (CO2-WAG) injection process. By integrating DenseNet and SPP modules, this method effectively captures and processes complex spatial features in tight reservoirs. Concurrently, the LSTM enhanced with SA mechanisms improves the prediction capability of temporal data during the CO2-WAG process. Experimental results demonstrate that the CSAL model performs excellently in both the training and testing phases, achieving a coefficient of determination (R2) exceeding 0.98, significantly enhancing the model's prediction accuracy. Compared to models without attention mechanisms, the CSAL model increases the R2 value in time series prediction by 10%. Furthermore, employing the Ensemble Smoother with Multiple Data Assimilation algorithm, the CSAL model achieves high-precision history matching, significantly reducing the error between predicted values and actual observations. This study validates the application potential and superiority of the CSAL model in the CO2-WAG process in tight reservoirs.
本研究将卷积神经网络、空间金字塔池化和具有自我注意（SA）机制的长短期记忆网络（LSTM）（缩写为 CSAL）结合起来，以解决致密油藏在注入 CO2 水-伴生气（CO2-WAG）过程中的生产动态预测问题。通过整合 DenseNet 和 SPP 模块，该方法有效地捕捉并处理了致密油藏中复杂的空间特征。同时，利用 SA 机制增强的 LSTM 提高了对 CO2-WAG 过程中时间数据的预测能力。实验结果表明，CSAL 模型在训练和测试阶段均表现出色，决定系数（R2）超过 0.98，显著提高了模型的预测精度。与没有注意力机制的模型相比，CSAL 模型在时间序列预测方面的 R2 值提高了 10%。此外，CSAL 模型采用了多数据同化的集合平滑算法（Ensemble Smoother with Multiple Data Assimilation），实现了高精度的历史匹配，大大降低了预测值与实际观测值之间的误差。这项研究验证了 CSAL 模型在致密油藏 CO2-WAG 过程中的应用潜力和优越性。
{"title":"Advanced attention-based spatial-temporal neural networks for enhanced CO2 water-alternating-gas performance prediction and history matching","authors":"Yunfeng Xu, Hui Zhao, Ranjith Pathegama Gamage, Qilong Chen, Yuhui Zhou, Xiang Rao","doi":"10.1063/5.0228397","DOIUrl":"https://doi.org/10.1063/5.0228397","url":null,"abstract":"This study combines convolutional neural networks, spatial pyramid pooling, and long short-term memory networks (LSTM) with self-attention (SA) mechanisms (abbreviated as CSAL) to address the problem of production dynamics prediction in tight reservoirs during the CO2 water-alternating-gas (CO2-WAG) injection process. By integrating DenseNet and SPP modules, this method effectively captures and processes complex spatial features in tight reservoirs. Concurrently, the LSTM enhanced with SA mechanisms improves the prediction capability of temporal data during the CO2-WAG process. Experimental results demonstrate that the CSAL model performs excellently in both the training and testing phases, achieving a coefficient of determination (R2) exceeding 0.98, significantly enhancing the model's prediction accuracy. Compared to models without attention mechanisms, the CSAL model increases the R2 value in time series prediction by 10%. Furthermore, employing the Ensemble Smoother with Multiple Data Assimilation algorithm, the CSAL model achieves high-precision history matching, significantly reducing the error between predicted values and actual observations. This study validates the application potential and superiority of the CSAL model in the CO2-WAG process in tight reservoirs.","PeriodicalId":20066,"journal":{"name":"Physics of Fluids","volume":null,"pages":null},"PeriodicalIF":4.6,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142218320","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We develop an approximated method to solve analytically the equations of motion that describe mooring line dynamics in a one-dimensional model. For the first time, we derive integral closed-form expressions to compute dynamic properties of mooring lines subject to ocean currents and waves of arbitrary time and spatial dependence, in terms of modified Bessel functions. This is done by decomposing the mooring line in three regions where different approximations and mathematical techniques of solution are carried out. Our analytical results provide a robust framework to simulate and analyze extreme realistic oceanic events when data from in situ ocean observation systems are available, regardless of the resolution or coarseness of subsurface measurements and even for long acquisition times. In order to prove the advantages of this approach, we have processed data from two stations in the National Data Buoy Center of the National Oceanic and Atmospheric Administration. From simulations with ocean currents data, we have gained insights into the coupling of the spatial modulation of ocean currents with the characteristic wavelengths of elastic lines. From simulations with ocean waves data, we have defined a scheme to analyze wave data and identify the contribution of each subset of frequency peaks to the net fluctuation of mooring line tension. This could be useful for classification of irregular waves based on their impact on mooring line tension. The development of better tools that integrate theoretical and experimental findings is necessary for the assessment of marine structures under the environmental conditions associated with climate change.
{"title":"A theoretical framework for robust implementation of in situ measurements of ocean currents and waves in dynamics of mooring systems","authors":"Ulises Torres-Herrera, Alireza Keramat, Huan-Feng Duan","doi":"10.1063/5.0221879","DOIUrl":"https://doi.org/10.1063/5.0221879","url":null,"abstract":"We develop an approximated method to solve analytically the equations of motion that describe mooring line dynamics in a one-dimensional model. For the first time, we derive integral closed-form expressions to compute dynamic properties of mooring lines subject to ocean currents and waves of arbitrary time and spatial dependence, in terms of modified Bessel functions. This is done by decomposing the mooring line in three regions where different approximations and mathematical techniques of solution are carried out. Our analytical results provide a robust framework to simulate and analyze extreme realistic oceanic events when data from in situ ocean observation systems are available, regardless of the resolution or coarseness of subsurface measurements and even for long acquisition times. In order to prove the advantages of this approach, we have processed data from two stations in the National Data Buoy Center of the National Oceanic and Atmospheric Administration. From simulations with ocean currents data, we have gained insights into the coupling of the spatial modulation of ocean currents with the characteristic wavelengths of elastic lines. From simulations with ocean waves data, we have defined a scheme to analyze wave data and identify the contribution of each subset of frequency peaks to the net fluctuation of mooring line tension. This could be useful for classification of irregular waves based on their impact on mooring line tension. The development of better tools that integrate theoretical and experimental findings is necessary for the assessment of marine structures under the environmental conditions associated with climate change.","PeriodicalId":20066,"journal":{"name":"Physics of Fluids","volume":null,"pages":null},"PeriodicalIF":4.6,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142218344","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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