Multiphase flow with boiling in parallel channels is often an efficient approach to managing heat and energy distribution in several engineering systems. However, two-phase flow with heating in parallel channels is prone to maldistribution, which can result in sub-optimal performance and, in some cases, permanent damage to the system. This challenge requires accurate flow modeling in parallel channels to mitigate or design against the adverse effect of two-phase flow maldistribution. The nonlinear nature of the multiphase flow model can yield multiple solutions for the same operating condition, creating significant challenges in predicting flow distribution. This study addresses this challenge by applying the entropy balance analysis and the conservation of mass, momentum, and energy to predict two-phase flow distribution in two thermally isolated parallel channels with a numerical model. Our model predictions and experiments show that equally distributed flow can become severely maldistributed with a decrease in flow rate, accompanied by a significant (>30%) change in the entropy generation rate. We show that the entropy balance analysis can distinguish between stable and unstable flows and identify the most feasible flow distribution in thermally decoupled parallel channels.
{"title":"Using entropy balance to determine multiphase flow distribution in thermally decoupled parallel channels with shared inlet and outlet headers","authors":"Toochukwu Aka, Shankar Narayan","doi":"10.1063/5.0207373","DOIUrl":"https://doi.org/10.1063/5.0207373","url":null,"abstract":"Multiphase flow with boiling in parallel channels is often an efficient approach to managing heat and energy distribution in several engineering systems. However, two-phase flow with heating in parallel channels is prone to maldistribution, which can result in sub-optimal performance and, in some cases, permanent damage to the system. This challenge requires accurate flow modeling in parallel channels to mitigate or design against the adverse effect of two-phase flow maldistribution. The nonlinear nature of the multiphase flow model can yield multiple solutions for the same operating condition, creating significant challenges in predicting flow distribution. This study addresses this challenge by applying the entropy balance analysis and the conservation of mass, momentum, and energy to predict two-phase flow distribution in two thermally isolated parallel channels with a numerical model. Our model predictions and experiments show that equally distributed flow can become severely maldistributed with a decrease in flow rate, accompanied by a significant (>30%) change in the entropy generation rate. We show that the entropy balance analysis can distinguish between stable and unstable flows and identify the most feasible flow distribution in thermally decoupled parallel channels.","PeriodicalId":509470,"journal":{"name":"Physics of Fluids","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141131921","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Schon Fusco, Lingyue Liu, M. Cabrerizo-Vílchez, E. Koos, M. Rodríguez-Valverde
This study explores the effects of nanoparticles on the dynamics of drop spreading under external vibration, presenting an advance in the understanding of nanofluid behavior on vibrating substrates. This work introduces insights into nanoparticle-mediated drop spreading, offering implications for improving particulate coatings, mini-mixers, and particle segregation technologies. By employing a twofold approach that combines oscillating drop dynamics with internal flow pattern analysis, we find how even small concentrations of hydrophilic or hydrophobized silica nanoparticles inside water sessile droplets significantly alter the spreading process on silanized glass surfaces. Our study allows distinct drop spreading regimes to be identified based on nanoparticle concentration and vibration amplitude, for both hydrophilic and hydrophobized nanoparticles. Through a comprehensive analysis, we demonstrate that the vibration-triggered spreading of nanofluids can lead to a stable and controlled manipulation of complex liquids.
{"title":"Vibration-triggered spreading of nanofluid drops","authors":"Schon Fusco, Lingyue Liu, M. Cabrerizo-Vílchez, E. Koos, M. Rodríguez-Valverde","doi":"10.1063/5.0205785","DOIUrl":"https://doi.org/10.1063/5.0205785","url":null,"abstract":"This study explores the effects of nanoparticles on the dynamics of drop spreading under external vibration, presenting an advance in the understanding of nanofluid behavior on vibrating substrates. This work introduces insights into nanoparticle-mediated drop spreading, offering implications for improving particulate coatings, mini-mixers, and particle segregation technologies. By employing a twofold approach that combines oscillating drop dynamics with internal flow pattern analysis, we find how even small concentrations of hydrophilic or hydrophobized silica nanoparticles inside water sessile droplets significantly alter the spreading process on silanized glass surfaces. Our study allows distinct drop spreading regimes to be identified based on nanoparticle concentration and vibration amplitude, for both hydrophilic and hydrophobized nanoparticles. Through a comprehensive analysis, we demonstrate that the vibration-triggered spreading of nanofluids can lead to a stable and controlled manipulation of complex liquids.","PeriodicalId":509470,"journal":{"name":"Physics of Fluids","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141134575","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this study, the wake of a cylinder was actively controlled by the cylinder's oscillatory morphing surface. Experiments were conducted in a closed-loop water channel. A cylinder of diameter 36 mm was placed in 0.09 m/s water flow, resulting in the Reynolds number 3240 and the vortex shedding frequency around 0.5 Hz. The cylinder's morphing surface oscillated at four different frequencies, i.e., 0.5, 1, 2, and 4 Hz. It was found that, compared to the rigid circular cylinder, the cylinder with oscillatory morphing surface can generally produce a smaller vortex formation length, especially at intermediate oscillation frequencies. The shear layers developed from the cylinder transit and roll up earlier due to enhanced flow instabilities. With the highest-frequency oscillations, the shear layer develops into a train of many small vortices that follow the trace of undisturbed shear layer. This study reveals some physical insights into this novel flow control method, which could be useful in future engineering applications.
{"title":"Control of cylinder wake using oscillatory morphing surface","authors":"Lingwei Zeng, T. H. New, Hui Tang","doi":"10.1063/5.0208868","DOIUrl":"https://doi.org/10.1063/5.0208868","url":null,"abstract":"In this study, the wake of a cylinder was actively controlled by the cylinder's oscillatory morphing surface. Experiments were conducted in a closed-loop water channel. A cylinder of diameter 36 mm was placed in 0.09 m/s water flow, resulting in the Reynolds number 3240 and the vortex shedding frequency around 0.5 Hz. The cylinder's morphing surface oscillated at four different frequencies, i.e., 0.5, 1, 2, and 4 Hz. It was found that, compared to the rigid circular cylinder, the cylinder with oscillatory morphing surface can generally produce a smaller vortex formation length, especially at intermediate oscillation frequencies. The shear layers developed from the cylinder transit and roll up earlier due to enhanced flow instabilities. With the highest-frequency oscillations, the shear layer develops into a train of many small vortices that follow the trace of undisturbed shear layer. This study reveals some physical insights into this novel flow control method, which could be useful in future engineering applications.","PeriodicalId":509470,"journal":{"name":"Physics of Fluids","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141137004","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
B. Wei, Yang Zhang, Jian Hou, Dong Zhao, Yongge Liu, Zhixin Guo, Xiaoke Yang
The porous media structure of the oil/gas reservoir changes greatly after long-term development, which subsequently influences the macroscopic relative permeability. To clarify the effects of microscopic pore-throat structure on macroscopic relative permeability, we first proposed a method to generate two-dimensional porous media images with adjustable structure parameters. The method is based on Delaunay triangulation and is similar to the pore-network generation process, which can provide binary images for direct numerical simulation of flow through porous media. Then, we established the single component multiphase Shan–Chen lattice Boltzmann method coupling the real gas equation of state. Finally, we discussed the effect of pore radius, coordination number, pore-throat ratio, pore shape, and wettability on the gas–liquid relative permeability curve using the lattice Boltzmann simulation. This study provides an effective method to generate porous media and explain the mechanism of relative permeability change at the pore scale.
{"title":"Effects of microscopic pore-throat structure on gas–liquid relative permeability: Porous media construction and pore-scale simulation","authors":"B. Wei, Yang Zhang, Jian Hou, Dong Zhao, Yongge Liu, Zhixin Guo, Xiaoke Yang","doi":"10.1063/5.0205591","DOIUrl":"https://doi.org/10.1063/5.0205591","url":null,"abstract":"The porous media structure of the oil/gas reservoir changes greatly after long-term development, which subsequently influences the macroscopic relative permeability. To clarify the effects of microscopic pore-throat structure on macroscopic relative permeability, we first proposed a method to generate two-dimensional porous media images with adjustable structure parameters. The method is based on Delaunay triangulation and is similar to the pore-network generation process, which can provide binary images for direct numerical simulation of flow through porous media. Then, we established the single component multiphase Shan–Chen lattice Boltzmann method coupling the real gas equation of state. Finally, we discussed the effect of pore radius, coordination number, pore-throat ratio, pore shape, and wettability on the gas–liquid relative permeability curve using the lattice Boltzmann simulation. This study provides an effective method to generate porous media and explain the mechanism of relative permeability change at the pore scale.","PeriodicalId":509470,"journal":{"name":"Physics of Fluids","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141134323","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In geophysical hydrodynamics, baroclinic instability denotes the process in which the perturbations draw the energy from the mean flow potential power. Researchers focus their attention on the baroclinic instability in the Earth's atmosphere and oceans for the meteorological diagnosis and prediction. Under investigation in this paper is a repulsive nonlinear system modeling the marginally unstable baroclinic wave packets in a baroclinic flow. With respect to the amplitude of the baroclinic wave packet and correction to the mean flow resulting from the self-rectification of the baroclinic wave, we present a Lax pair with the changeable parameters and then derive the N-dark-dark soliton solutions, where N is a positive integer. Asymptotic analysis on the N-dark-dark solitons is processed to obtain the algebraic expressions of the N-dark-dark soliton components. We find that the obtained phase shift of each dark-dark soliton component is relevant with the N − 1 spectral parameters. Furthermore, we take N = 3 as an example and graphically illustrate the 3-dark-dark solitons, which are consistent with our asymptotic-analysis results. Our analysis may provide the explanations of the complex and variable natural mechanisms of the baroclinic instability.
在地球物理流体力学中，气压不稳定性是指扰动从平均流动势能中汲取能量的过程。研究人员重点关注地球大气和海洋中的巴氏不稳定性，以进行气象诊断和预测。本文研究的是一个斥力非线性系统，它模拟了条气流中的边际不稳定条气流波包。针对条纹波包的振幅和条纹波自校正产生的平均流修正，我们提出了参数可变的拉克斯对，然后推导出 N-暗-暗孤子解，其中 N 为正整数。通过对 N-暗-暗孤子的渐近分析，我们得到了 N-暗-暗孤子分量的代数表达式。我们发现，每个暗-暗孤子分量的相移都与 N - 1 光谱参数有关。此外，我们还以 N = 3 为例，用图表说明了 3-暗-暗孤子，这与我们的渐近分析结果是一致的。我们的分析可以为复杂多变的巴氏不稳定性自然机制提供解释。
{"title":"Dark-soliton asymptotics for a repulsive nonlinear system in a baroclinic flow","authors":"Xi-Hu Wu, Yi-Tian Gao, Xin Yu","doi":"10.1063/5.0213090","DOIUrl":"https://doi.org/10.1063/5.0213090","url":null,"abstract":"In geophysical hydrodynamics, baroclinic instability denotes the process in which the perturbations draw the energy from the mean flow potential power. Researchers focus their attention on the baroclinic instability in the Earth's atmosphere and oceans for the meteorological diagnosis and prediction. Under investigation in this paper is a repulsive nonlinear system modeling the marginally unstable baroclinic wave packets in a baroclinic flow. With respect to the amplitude of the baroclinic wave packet and correction to the mean flow resulting from the self-rectification of the baroclinic wave, we present a Lax pair with the changeable parameters and then derive the N-dark-dark soliton solutions, where N is a positive integer. Asymptotic analysis on the N-dark-dark solitons is processed to obtain the algebraic expressions of the N-dark-dark soliton components. We find that the obtained phase shift of each dark-dark soliton component is relevant with the N − 1 spectral parameters. Furthermore, we take N = 3 as an example and graphically illustrate the 3-dark-dark solitons, which are consistent with our asymptotic-analysis results. Our analysis may provide the explanations of the complex and variable natural mechanisms of the baroclinic instability.","PeriodicalId":509470,"journal":{"name":"Physics of Fluids","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141142782","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fuel jet primary breakup strongly depends on the in-nozzle cavitation phenomena found in the high-pressure fuel injector nozzle. Nevertheless, limited attention has been paid to the mechanism of fuel jet primary breakup induced by in-nozzle vortex-induced string-type cavitation. This study involves simulations of in-nozzle string cavitating flow and simultaneously near-nozzle jet primary breakup process using large eddy simulation and volume of fluid, aiming at revealing the effects of string cavitation on jet primary breakup. The numerical results are in good agreement with experimental data in terms of string cavitation intensity, interfacial topology of jet, and spray spreading angle. The numerical investigations indicate that the external surface of the jet experiences Kelvin–Helmholtz instabilities, which results in the development of circumferential and axial surface waves at the fuel film surface. Subsequently, the fuel film surface undergoes progressive wrinkling, resulting in its breakup into multiple ligaments and large droplets. On the internal side of the jet, back-suction of air caused by negative pressure and its interaction with cavitation vapor at the core of the jet lead to the collapse of vapor bubbles. The resulting pressure waves and micro-jets facilitate the detachment of liquid sheets from the internal surface of the jet. Analysis of the enstrophy transport equation indicates that the driving mechanism behind string cavitation jet breakup further downstream is the baroclinic torque term, which is responsible for the generation of a cascade of smaller vortical structures. This effect dominates over vortex stretching and dilatation terms.
{"title":"Primary breakup of a jet coupled with vortex-induced string cavitation in a fuel injector nozzle","authors":"Wei Guan, Yunlong Huang, Zhixia He, Genmiao Guo, Chuqiao Wang, Dominique Thévenin","doi":"10.1063/5.0204584","DOIUrl":"https://doi.org/10.1063/5.0204584","url":null,"abstract":"Fuel jet primary breakup strongly depends on the in-nozzle cavitation phenomena found in the high-pressure fuel injector nozzle. Nevertheless, limited attention has been paid to the mechanism of fuel jet primary breakup induced by in-nozzle vortex-induced string-type cavitation. This study involves simulations of in-nozzle string cavitating flow and simultaneously near-nozzle jet primary breakup process using large eddy simulation and volume of fluid, aiming at revealing the effects of string cavitation on jet primary breakup. The numerical results are in good agreement with experimental data in terms of string cavitation intensity, interfacial topology of jet, and spray spreading angle. The numerical investigations indicate that the external surface of the jet experiences Kelvin–Helmholtz instabilities, which results in the development of circumferential and axial surface waves at the fuel film surface. Subsequently, the fuel film surface undergoes progressive wrinkling, resulting in its breakup into multiple ligaments and large droplets. On the internal side of the jet, back-suction of air caused by negative pressure and its interaction with cavitation vapor at the core of the jet lead to the collapse of vapor bubbles. The resulting pressure waves and micro-jets facilitate the detachment of liquid sheets from the internal surface of the jet. Analysis of the enstrophy transport equation indicates that the driving mechanism behind string cavitation jet breakup further downstream is the baroclinic torque term, which is responsible for the generation of a cascade of smaller vortical structures. This effect dominates over vortex stretching and dilatation terms.","PeriodicalId":509470,"journal":{"name":"Physics of Fluids","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141134900","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
As a representative model in the investigation into fluid–structure coupling, a flexible film interacting with the wake of a circular cylinder involves intricate patterns of both solid motion and fluid evolution. Recent investigations have found that the interactions could be either periodic or aperiodic in experiments; the latter, however, is often overlooked. In this work, the irregular aperiodic flutter of a flexible film behind a circular cylinder is investigated experimentally. It is determined that the irregular flutter intermittently exhibits transient quasi-periodic mode and aperiodic mode. The former is accompanied by the large-scale vortices alternatively formed against the film surfaces, while the latter is associated with vortices formed downstream of the film's trailing edge, so that the whole film is enveloped by the extended shear layers. In order to separate the data individually pertaining to each of the two modes from the whole dataset, a motion-mode recognition method is proposed, and then conditional statistics of flow fields are achieved. The quasi-periodic mode corresponds to more intense velocity fluctuations in the wake, while in the aperiodic mode, the observed localized instability of shear layers induces an increase in the local streamwise velocity fluctuation.
{"title":"Mode transition of a film fluttering in a circular cylinder wake","authors":"Fan Duan, Jinjun Wang","doi":"10.1063/5.0210731","DOIUrl":"https://doi.org/10.1063/5.0210731","url":null,"abstract":"As a representative model in the investigation into fluid–structure coupling, a flexible film interacting with the wake of a circular cylinder involves intricate patterns of both solid motion and fluid evolution. Recent investigations have found that the interactions could be either periodic or aperiodic in experiments; the latter, however, is often overlooked. In this work, the irregular aperiodic flutter of a flexible film behind a circular cylinder is investigated experimentally. It is determined that the irregular flutter intermittently exhibits transient quasi-periodic mode and aperiodic mode. The former is accompanied by the large-scale vortices alternatively formed against the film surfaces, while the latter is associated with vortices formed downstream of the film's trailing edge, so that the whole film is enveloped by the extended shear layers. In order to separate the data individually pertaining to each of the two modes from the whole dataset, a motion-mode recognition method is proposed, and then conditional statistics of flow fields are achieved. The quasi-periodic mode corresponds to more intense velocity fluctuations in the wake, while in the aperiodic mode, the observed localized instability of shear layers induces an increase in the local streamwise velocity fluctuation.","PeriodicalId":509470,"journal":{"name":"Physics of Fluids","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141142540","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Marcel Bock, Khaled Yassin, H. Kassem, Johannes Theron, L. J. Lukassen, Joachim Peinke
Gaussian and intermittent synthetically generated turbulences are investigated as initial conditions for high-resolution numerical simulations. Turbulent fields, namely the Mann and the intermittent Time-mapped Mann model, are injected into large eddy simulations, and subsequently their convergences are investigated. In addition to the usual one-point and two-point characterizations, the higher moments of the velocity increments are addressed to grasp the intermittency. Here, we show that independent of the initial conditions, the evolving turbulence converges to a common state, which is well represented by the classical intermittent turbulence of Kolmogorov. The findings reveal that if the intermittency parameters of the inflow field are adjusted to those of the common state, the convergence behavior is much faster.
{"title":"Intermittency, an inevitable feature for faster convergence of large eddy simulations","authors":"Marcel Bock, Khaled Yassin, H. Kassem, Johannes Theron, L. J. Lukassen, Joachim Peinke","doi":"10.1063/5.0202514","DOIUrl":"https://doi.org/10.1063/5.0202514","url":null,"abstract":"Gaussian and intermittent synthetically generated turbulences are investigated as initial conditions for high-resolution numerical simulations. Turbulent fields, namely the Mann and the intermittent Time-mapped Mann model, are injected into large eddy simulations, and subsequently their convergences are investigated. In addition to the usual one-point and two-point characterizations, the higher moments of the velocity increments are addressed to grasp the intermittency. Here, we show that independent of the initial conditions, the evolving turbulence converges to a common state, which is well represented by the classical intermittent turbulence of Kolmogorov. The findings reveal that if the intermittency parameters of the inflow field are adjusted to those of the common state, the convergence behavior is much faster.","PeriodicalId":509470,"journal":{"name":"Physics of Fluids","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141140807","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Lu Qiao, Shengyu Yang, Qinhong Hu, Huijun Wang, Taohua He
Porosity is a pivotal factor affecting the capacity for storage and extraction in shale reservoirs. The paucity of labeled data in conventional well logs interpretation and supervised learning models leads to inadequate generalization and diminished prediction accuracy, thus limiting their effectiveness in precise porosity evaluation. This study introduces a contrastive learning – convolutional neural network (CL-CNN) framework that utilizes CL for pretraining on a vast array of unlabeled data, followed by fine-tuning using a traditional CNN on a curated set of labeled data. Applied to the Subei Basin in Eastern China, the framework was tested on 130 labeled data and 2576 unlabeled data points from well H1. The results indicate that the CL-CNN framework outperforms traditional CNN-based supervised learning and other machine learning models in terms of prediction accuracy for the dataset under consideration. Furthermore, it demonstrates the potential for extensive porosity assessment across different logged depths. Due to its efficacy and ease of use, the proposed framework is versatile enough for application in reservoir evaluation, engineering development, and related fields. The innovative contribution of this research is encapsulated in its unique methodology and procedural steps for the accurate prediction of shale reservoir porosity, thus significantly enriching the existing body of knowledge in this domain.
{"title":"Unsupervised contrastive learning: Shale porosity prediction based on conventional well logging","authors":"Lu Qiao, Shengyu Yang, Qinhong Hu, Huijun Wang, Taohua He","doi":"10.1063/5.0206449","DOIUrl":"https://doi.org/10.1063/5.0206449","url":null,"abstract":"Porosity is a pivotal factor affecting the capacity for storage and extraction in shale reservoirs. The paucity of labeled data in conventional well logs interpretation and supervised learning models leads to inadequate generalization and diminished prediction accuracy, thus limiting their effectiveness in precise porosity evaluation. This study introduces a contrastive learning – convolutional neural network (CL-CNN) framework that utilizes CL for pretraining on a vast array of unlabeled data, followed by fine-tuning using a traditional CNN on a curated set of labeled data. Applied to the Subei Basin in Eastern China, the framework was tested on 130 labeled data and 2576 unlabeled data points from well H1. The results indicate that the CL-CNN framework outperforms traditional CNN-based supervised learning and other machine learning models in terms of prediction accuracy for the dataset under consideration. Furthermore, it demonstrates the potential for extensive porosity assessment across different logged depths. Due to its efficacy and ease of use, the proposed framework is versatile enough for application in reservoir evaluation, engineering development, and related fields. The innovative contribution of this research is encapsulated in its unique methodology and procedural steps for the accurate prediction of shale reservoir porosity, thus significantly enriching the existing body of knowledge in this domain.","PeriodicalId":509470,"journal":{"name":"Physics of Fluids","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141031536","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A high-fidelity multiphase flow computational model is utilized to investigate the interaction mechanism between anti-phase tandem bubbles and tissue materials in a free-field environment. The formation of liquid jets generated by tandem bubble coupling and its effects on tissue deformation are analyzed. Parametric studies are conducted to explore the impacts of bubble–bubble distance (γbb), bubble size ratio (Sbb), and bubble–tissue distance (γtb). The results indicate that the regime of tissue penetration varies under different γbb. For small γbb, the tissue deformation is mainly attributed to the stretching of upper bubbles and liquid jets; whereas for large γbb, tissue deformation is primarily induced by the jets themselves; and for moderate γbb values, it is caused by a combined effect involving both jets and the evolution of toroidal bubbles. Comparative analysis shows the significant impact of varying Sbb on bubble coupling dynamics, with larger Sbb values correlating with more potent tissue penetration. Furthermore, the study also reveals that, beyond γtb exceeding 3, penetration ceases to manifest, advocating for the maintenance of γtb below 1.4 for practical applications.
{"title":"Dynamics of tandem bubble interaction near tissue","authors":"Junjie Zhao, Jingzhu Wang, Shunxiang Cao","doi":"10.1063/5.0201811","DOIUrl":"https://doi.org/10.1063/5.0201811","url":null,"abstract":"A high-fidelity multiphase flow computational model is utilized to investigate the interaction mechanism between anti-phase tandem bubbles and tissue materials in a free-field environment. The formation of liquid jets generated by tandem bubble coupling and its effects on tissue deformation are analyzed. Parametric studies are conducted to explore the impacts of bubble–bubble distance (γbb), bubble size ratio (Sbb), and bubble–tissue distance (γtb). The results indicate that the regime of tissue penetration varies under different γbb. For small γbb, the tissue deformation is mainly attributed to the stretching of upper bubbles and liquid jets; whereas for large γbb, tissue deformation is primarily induced by the jets themselves; and for moderate γbb values, it is caused by a combined effect involving both jets and the evolution of toroidal bubbles. Comparative analysis shows the significant impact of varying Sbb on bubble coupling dynamics, with larger Sbb values correlating with more potent tissue penetration. Furthermore, the study also reveals that, beyond γtb exceeding 3, penetration ceases to manifest, advocating for the maintenance of γtb below 1.4 for practical applications.","PeriodicalId":509470,"journal":{"name":"Physics of Fluids","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141029032","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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