Physics of Fluids最新文献_第2页

Wetting and pressure gradient performance in a lattice Boltzmann color gradient model 晶格玻尔兹曼颜色梯度模型中的润湿和压力梯度性能

IF 4.6 2区工程技术

Physics of Fluids Pub Date : 2024-09-18 DOI: 10.1063/5.0228835

M. Sedahmed, R. C. V. Coelho

{"title":"Wetting and pressure gradient performance in a lattice Boltzmann color gradient model","authors":"M. Sedahmed, R. C. V. Coelho","doi":"10.1063/5.0228835","DOIUrl":"https://doi.org/10.1063/5.0228835","url":null,"abstract":"An accurate implementation of wetting and pressure drop is crucial to correctly reproduce fluid displacement processes in porous media. Although several strategies have been proposed in the literature, a systematic comparison of them is needed to determine the most suitable for practical applications. Here, we carried out numerical simulations to investigate the performance of two widely used wettability schemes in the lattice Boltzmann color gradient model, namely, the geometrical wetting scheme by Leclaire et al. [Phys. Rev. E 95(3), 033306 (2017)](scheme-I) and the modified direction of the color gradient scheme by Akai et al. [Adv. Water Resour. 116, 56–66 (2018)] (scheme-II). We showed that scheme-II was more accurate in simulating static contact angles of a fluid droplet on a solid surface. However, scheme-I was more accurate in simulating a dynamic case of a binary fluid flow in a horizontal capillary tube described by the Washburn equation. Moreover, we investigated the performance of two popular pressure gradient implementation types. Type-I used the so-called Zou–He pressure boundary conditions at the inlet and the outlet of the domain, while type-II used an external body force as a pressure gradient. We showed that the type-I implementation was slightly more accurate in simulating a neutrally wetting fluid in a horizontal capillary tube described by the Washburn equation. We also investigated the differences between the two types of pressure gradient implementation in simulating two fluid displacement processes in a Bentheimer sandstone rock sample: the primary drainage and the imbibition displacement processes.","PeriodicalId":20066,"journal":{"name":"Physics of Fluids","volume":null,"pages":null},"PeriodicalIF":4.6,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142258835","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}

引用次数: 0

Effects of axisymmetric confinement on vortical structures emanating from round turbulent jets 轴对称约束对圆形湍流喷流涡旋结构的影响

IF 4.6 2区工程技术

Physics of Fluids Pub Date : 2024-09-18 DOI: 10.1063/5.0224877

J. Adjetey, K. Fukuda, R. Balachandar

{"title":"Effects of axisymmetric confinement on vortical structures emanating from round turbulent jets","authors":"J. Adjetey, K. Fukuda, R. Balachandar","doi":"10.1063/5.0224877","DOIUrl":"https://doi.org/10.1063/5.0224877","url":null,"abstract":"Confined jets occur in many engineering applications including combustion chambers, jet pumps, and chemical reactors. The effects of axisymmetric confinement on the vortical structures identified in a turbulent jet are investigated using large eddy simulation at a Reynolds number of 30 000 (based on nozzle exit conditions) and expansion ratio (chamber-to-nozzle diameter ratio) of five. The results obtained from the confined jet are compared with those of a free jet under the same nozzle exit flow conditions. A prominent recirculation zone forms between the expanding jet and the confining wall, resulting in early shear layer distortion and a shorter interaction length in the confined jet (0.85 jet diameters) compared to the free jet (1.15 jet diameters). Using the λ2 criterion for vortex identification, two dominant structural modes are identified in the near-exit region of the free jet: ring and helical modes. However, in the confined jet, the helical mode is absent, and the turbulent confined fluid accelerates the breakup of the ring vortices. The interaction of the secondary line vortices with the breaking structures leads to the formation of new hairpin-like vortices, which also contribute to further vortex breakup. These results explain the enhanced mixing performance of confined jets as the mixing is directly tied to the breakup of large vortical structures. Proper orthogonal decomposition modes are also presented to identify the structures/events with the highest contribution to the total turbulent kinetic energy in both flow fields.","PeriodicalId":20066,"journal":{"name":"Physics of Fluids","volume":null,"pages":null},"PeriodicalIF":4.6,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142258779","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}

引用次数: 0

Heterogeneity properties and permeability of shale matrix at nano-scale and micron-scale 页岩基质在纳米和微米尺度上的异质性和渗透性

IF 4.6 2区工程技术

Physics of Fluids Pub Date : 2024-09-18 DOI: 10.1063/5.0223200

Bowen Hu, Yongjie Ren, Rui Sun, Shengcheng Wang, Shanjie Su

{"title":"Heterogeneity properties and permeability of shale matrix at nano-scale and micron-scale","authors":"Bowen Hu, Yongjie Ren, Rui Sun, Shengcheng Wang, Shanjie Su","doi":"10.1063/5.0223200","DOIUrl":"https://doi.org/10.1063/5.0223200","url":null,"abstract":"Heterogeneity of shale pores at nano-scale and micrometer-scale is of great significance to gas transport properties. In this study, the pore structure of shale samples from lower Silurian Longmaxi Formation in the Sichuan basin is investigated by field emission-scanning electron microscopy (FE-SEM) and x-ray micro-computed tomography (Xμ-CT) technology. Based on fractal theory, the lacunarity is introduced to describe the clustering degree of pores in shale matrix, which can compensate for the limitations of fractal dimension. Combining lacunarity with fractal dimension allows for quantification of subtle differences in pore spatial distribution. For FE-SEM images at nano-scales, the fractal dimension changes in a “U” shape, while lacunarity changes in a “∩” shape. For Xμ-CT images at micrometer-scale, both the fractal dimension and lacunarity change in a logarithmic function. Lacunarity at both nano-scale and micrometer-scale linearly decreases with the increase in fractal dimension. By three-dimensional (3D) pore network modeling analysis, the structure properties of the connected pores, such as the number of pores and throats, pore diameter, pore volume, pore surface, throat length, and coordination number, are quantitatively calculated, and these structure parameters show strong heterogeneity. The average coordination number of the connected pores ranges in 2.92–4.36. This indicates that these pores in shale matrix have poor connectivity. The permeability varies from 0.06 to 0.17 μm2 in two-dimensional (2D) Xμ-CT images but from 3.20 to 34.99 μm2 in a 3D structure. The permeability in the 3D structure is about two order higher in magnitude than that in the 2D Xμ-CT images.","PeriodicalId":20066,"journal":{"name":"Physics of Fluids","volume":null,"pages":null},"PeriodicalIF":4.6,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142258776","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}

引用次数: 0

Axisymmetric phase-field-based lattice Boltzmann model for incompressible two-phase flow with phase change 基于轴对称相场的不可压缩两相流相变晶格玻尔兹曼模型

IF 4.6 2区工程技术

Physics of Fluids Pub Date : 2024-09-18 DOI: 10.1063/5.0226691

Chunhua Zhang, Wenyuan Hou, Qin Lou, Liang Wang, Hantao Liu, Zhaoli Guo

{"title":"Axisymmetric phase-field-based lattice Boltzmann model for incompressible two-phase flow with phase change","authors":"Chunhua Zhang, Wenyuan Hou, Qin Lou, Liang Wang, Hantao Liu, Zhaoli Guo","doi":"10.1063/5.0226691","DOIUrl":"https://doi.org/10.1063/5.0226691","url":null,"abstract":"In this work, a phase-field-based lattice Boltzmann equation (LBE) model for axisymmetric two-phase flow with phase change is proposed. Two sets of discrete particle distribution functions are employed to match the conserved Allen–Cahn equation and the hydrodynamic equations with phase change effect, respectively. Since phase change occurs at the interface, the divergence-free condition of the velocity field is no longer satisfied due to mass transfer, and the conserved Allen–Cahn equation needs to be equipped with a source term dependent on the phase change model. To deal with these, a novel source term in the hydrodynamic LBE is delicately designed to recover the correct target governing equations. Meanwhile, the LBE for the Allen–Cahn equation is modified with a discrete force term to model mass transfer. In particular, an additional correction term is added into the hydrodynamic LBE to reduce the spurious velocity and improve numerical stability. Several axisymmetric benchmark multiphase problems with phase change, including bubble growing in superheated liquid, D2 law, film boiling, bubble rising in superheated liquid under gravity, and droplet impact on a hot surface, have been conducted to test the performance of the proposed model. Numerical results agree well with analytical solutions and available published data in the literature.","PeriodicalId":20066,"journal":{"name":"Physics of Fluids","volume":null,"pages":null},"PeriodicalIF":4.6,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142258783","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}

引用次数: 0

Research on icing model and calculation methods 结冰模型和计算方法研究

IF 4.6 2区工程技术

Physics of Fluids Pub Date : 2024-09-18 DOI: 10.1063/5.0226037

Yaping Hu, Jiheng Pan, Yong Liu, Changxian Zhang, Yuetao Jiang, Jiangnan Zhu

{"title":"Research on icing model and calculation methods","authors":"Yaping Hu, Jiheng Pan, Yong Liu, Changxian Zhang, Yuetao Jiang, Jiangnan Zhu","doi":"10.1063/5.0226037","DOIUrl":"https://doi.org/10.1063/5.0226037","url":null,"abstract":"Aircraft icing seriously threatens flight safety. This paper describes a modified shallow-water icing thermodynamic model that is applicable to unstructured grids and considers the effects of changes in water physical parameters and sublimation on icing. An icing calculation method enables the automatic determination of whether freezing occurs and the type of icing. An autonomous icing calculation program is developed to extract the geometric coordinates and mesh information of the icing surface and combine this information with the multiphase flow field of air-supercooled water droplets. The icing equations in the Godnov format are discretized to produce a large-scale sparse matrix that is solved iteratively using the biconjugate gradient stabilized method. The output includes parameter distributions for the ice thickness, water film thickness, and equilibrium temperature. Taking the National Advisory Committee for Aeronautic 0012 airfoil as the study object, the results of icing simulations are compared with experimental data from an ice wind tunnel and the ice shapes calculated by the FENSAP-ICE software. The results are found to be in good agreement with the experimental data, and the ice height errors at stagnation points are less than 15%. In the case of rime ice, single-horned ice shapes are simulated for both conventional and large supercooled droplets. For mixed ice and glaze ice, double-horned ice shapes are simulated for both droplet conditions. FENSAP-ICE fails to simulate the ice horns and produces large errors in ice thickness and ice range.","PeriodicalId":20066,"journal":{"name":"Physics of Fluids","volume":null,"pages":null},"PeriodicalIF":4.6,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142258725","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}

引用次数: 0

Unveiling the underlying physics of two-phase boiling heat transfer enhancement through shearing of coalescing bubbles 揭示通过剪切凝聚气泡增强两相沸腾传热的基本物理学原理

IF 4.6 2区工程技术

Physics of Fluids Pub Date : 2024-09-18 DOI: 10.1063/5.0227551

Niloy Laskar, Mihir K. Das

{"title":"Unveiling the underlying physics of two-phase boiling heat transfer enhancement through shearing of coalescing bubbles","authors":"Niloy Laskar, Mihir K. Das","doi":"10.1063/5.0227551","DOIUrl":"https://doi.org/10.1063/5.0227551","url":null,"abstract":"The upcoming energy scarcity problem has driven research toward developing energy-efficient two-phase heat exchangers essential for various cooling applications. This research is rooted in the principles of pool boiling, essential for effective heat transfer in various heat exchangers. A well-known reported problem in heat exchangers is the dry-out phenomena of heated surfaces due to bubble coalescence. To tackle this undesirable problem, an innovative technique has been introduced in this study, which involves the shearing of bubbles through liquid jet impingement over the heated surface. The study has been carried out in a two-dimensional domain numerically, in the wall superheat range of 9–16 K. To study the underlying physics involved in this pool boiling phenomenon, the bubble dynamics parameters such as departure frequency, bubble diameter, cold spot (bubble base) temperature, and vapor volume fraction have been analyzed. The results show that with the jet shearing effect, a maximum enhancement of 25% in heat transfer rate is observed at higher wall superheat. The investigation also highlights that the liquid jet enhances vapor volume fraction, indicating enhanced steam generation, particularly an enhancement of 27% observed at elevated wall superheat. An early onset necking effect is also observed with the shearing effect, which leads to the formation of smaller bubbles with higher departure frequencies. This study is a benchmark to the fundamental physics of enhancing two-phase heat transfer through bubble shearing, offering promising insights for energy conservation in two-phase heat exchanger design, particularly within the context of pool boiling.","PeriodicalId":20066,"journal":{"name":"Physics of Fluids","volume":null,"pages":null},"PeriodicalIF":4.6,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142258689","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}

引用次数: 0

Research on the attenuation of internal pressure in the large-span cylindrical roof building with a dominant gable opening 大跨度圆柱形屋顶建筑的内压衰减研究

IF 4.6 2区工程技术

Physics of Fluids Pub Date : 2024-09-18 DOI: 10.1063/5.0220765

Yuhang Ge, Ying Sun, Zhenggang Cao, Qiming Zhu

{"title":"Research on the attenuation of internal pressure in the large-span cylindrical roof building with a dominant gable opening","authors":"Yuhang Ge, Ying Sun, Zhenggang Cao, Qiming Zhu","doi":"10.1063/5.0220765","DOIUrl":"https://doi.org/10.1063/5.0220765","url":null,"abstract":"The internal to external pressure ratio in a large-span cylindrical roof building with a dominant gable opening fluctuates dramatically between 0 and 1, significantly impacted by the attenuation of internal pressure. Current theories usually assume this ratio equal to 1 and overlook the attenuation effect. This study investigates four cylindrical roof models with varying opening areas, scale ratios, and wind speeds by wind tunnel tests. It analyzes ratios of mean (C¯pi/C¯pe), fluctuating (σpi/σpe), and peak (Ĉpi/Ĉpe) internal to external pressure to pinpoint factors affecting the internal pressure attenuation. The results highlight that the most pronounced internal pressure attenuation is at the sideward opening. The vortex shedding around the opening is induced by the wind direction, scale ratio, and wind speed. The attenuation effect decreases with lower frequencies of periodic vortex shedding. This effect generally vanishes when the windward or leeward opening ratio (A1.5/V0) exceeds 0.57%. Empirical design formulas are proposed to predict ratios of internal to external pressure considering the attenuation effect. The inertia (CI) and loss coefficients (CL) affected by the internal pressure attenuation are analyzed to estimate the air slug inertia and damping through the opening. A governing equation, incorporating reduction coefficients (C¯eddy, C̃eddy) from empirical design formulas, is applied to precisely compute the attenuated internal pressure in the large-span cylindrical roof building with a dominant gable opening for engineering risk assessment.","PeriodicalId":20066,"journal":{"name":"Physics of Fluids","volume":null,"pages":null},"PeriodicalIF":4.6,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142258777","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}

引用次数: 0

The effect of slip parameter in an axisymmetric oscillatory Stokes flow 轴对称振荡斯托克斯流中滑移参数的影响

IF 4.6 2区工程技术

Physics of Fluids Pub Date : 2024-09-18 DOI: 10.1063/5.0226315

Dadi Dimple S. S., B. Sri Padmavati

引用次数: 0

Large eddy simulation analysis of a model reactive tracer through spatial filtering 通过空间过滤对反应示踪模型进行大涡流模拟分析

IF 4.6 2区工程技术

Physics of Fluids Pub Date : 2024-09-18 DOI: 10.1063/5.0226039

S. Legare, M. Stastna

{"title":"Large eddy simulation analysis of a model reactive tracer through spatial filtering","authors":"S. Legare, M. Stastna","doi":"10.1063/5.0226039","DOIUrl":"https://doi.org/10.1063/5.0226039","url":null,"abstract":"Large eddy simulations (LES) provide a methodology for both analyzing and simulating multi-scale flows when the smallest scales of motion cannot be resolved. Within environmental flows there exist numerous biogeochemical processes involving tracers undergoing reactions. In this study, we perform an a posteriori LES analysis on a direct numerical simulation of an idealized model reactive tracer subjected to three-dimensional turbulence induced by a Rayleigh–Taylor instability. The governing equations, including an advection–diffusion–reaction equation for the reactive tracer, are filtered, and the resulting sub-filter-scale terms are expressed in terms of interactions between scales. The procedure is demonstrated for a generalized degree N polynomial reaction function. Various spectral filters are applied to the data and compared. The preferential choice is to use the widest filter possible with a smoothed cutoff. The sub-filter-scale reaction term that results from filtering the reaction function is considered for each of the filter choices. When using a particularly harsh filter, local balances are found for the resolved scale and cross-scale components of the sub-filter-scale reaction term. The same result is shown for the vertical sub-filter-scale flux for both a reactive and a passive tracer. The components of the sub-filter-scale reaction and vertical flux terms involving interactions at the sub-filter-scale do not show any evidence of local balances and are distributed around the fine turbulent structures in the flow. This suggests that parameterizations for the sub-filter-scale terms would benefit from considering event specific dynamics.","PeriodicalId":20066,"journal":{"name":"Physics of Fluids","volume":null,"pages":null},"PeriodicalIF":4.6,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142258778","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}

引用次数: 0

A parameter-free particle relaxation technique for smoothed particle hydrodynamics 平滑粒子流体力学的无参数粒子松弛技术

IF 4.6 2区工程技术

Physics of Fluids Pub Date : 2024-09-18 DOI: 10.1063/5.0223930

Hualin Zheng, Hongfu Qiang, Yujie Zhu, Chi Zhang

引用次数: 0