Physics of Fluids最新文献

The impact of blood viscosity modeling on computational fluid dynamic simulations of pediatric patients with Fontan circulation. 血液粘度建模对芳坦循环儿科患者计算流体动力学模拟的影响。

IF 4.1 2区工程技术

Physics of Fluids Pub Date : 2024-11-01 Epub Date: 2024-11-13 DOI: 10.1063/5.0236095

Heng Wei, Coskun Bilgi, Kellie Cao, Jon A Detterich, Niema M Pahlevan, Andrew L Cheng

{"title":"The impact of blood viscosity modeling on computational fluid dynamic simulations of pediatric patients with Fontan circulation.","authors":"Heng Wei, Coskun Bilgi, Kellie Cao, Jon A Detterich, Niema M Pahlevan, Andrew L Cheng","doi":"10.1063/5.0236095","DOIUrl":"10.1063/5.0236095","url":null,"abstract":"For univentricular heart patients, the Fontan circulation presents a unique pathophysiology due to chronic non-pulsatile low-shear-rate pulmonary blood flow, where non-Newtonian effects are likely substantial. This study evaluates the influence of non-Newtonian behavior of blood on fluid dynamics and energetic efficiency in pediatric patient-specific models of the Fontan circulation. We used immersed boundary-lattice Boltzmann method simulations to compare Newtonian and non-Newtonian viscosity models. The study included models from twenty patients exhibiting a low cardiac output state (cardiac index of 2 L/min/m2). We quantified metrics of energy loss (indexed power loss and viscous dissipation), non-Newtonian importance factors, and hepatic flow distribution. We observed significant differences in flow structure between Newtonian and non-Newtonian models. Specifically, the non-Newtonian simulations demonstrated significantly higher local and average viscosity, corresponding to a higher non-Newtonian importance factor and larger energy loss. Hepatic flow distribution was also significantly different in a subset of patients. These findings suggest that non-Newtonian behavior contributes to flow structure and energetic inefficiency in the low cardiac output state of the Fontan circulation.","PeriodicalId":20066,"journal":{"name":"Physics of Fluids","volume":"36 11","pages":"111911"},"PeriodicalIF":4.1,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11577338/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142688535","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Meso-scale investigation on the permeability of frozen soils with the lattice Boltzmann method 用晶格玻尔兹曼法对冻土的渗透性进行中尺度研究

IF 4.6 2区工程技术

Physics of Fluids Pub Date : 2024-09-20 DOI: 10.1063/5.0222658

Huxi Xia, Yuanming Lai, Mohaddeseh Mousavi-Nezhad

{"title":"Meso-scale investigation on the permeability of frozen soils with the lattice Boltzmann method","authors":"Huxi Xia, Yuanming Lai, Mohaddeseh Mousavi-Nezhad","doi":"10.1063/5.0222658","DOIUrl":"https://doi.org/10.1063/5.0222658","url":null,"abstract":"Complex composition and intricate pore-scale structure of frozen soils poses significant challenges in reliably and efficiently obtaining their permeability. In this study, we propose a modified quartet structure generation set (QSGS) numerical tool for generating frozen soils and present the development of a computational simulation code based on the multiple-relaxation-time lattice Boltzmann method (LBM). In the modified QSGS, the arc-shaped water-ice interface is depicted, and the influence of pore-scale geometry on freezing temperature is considered. The validity of combining the proposed QSGS model and the LBM code is proved by comparing calculated results to analytical and experimental results of porous media. Our objective was to investigate the effects of soil features, including porosity, grain diameter, shape anisotropy of soil particles, and ice content on the intrinsic permeability of frozen soil. Additionally, we examined the relationship between these features and the specific surface area and tortuosity. Numerical results show that the intrinsic permeability of frozen soils increases with increasing porosity, larger granular diameter, and anisotropy, which is identical with the pressure gradient. The presence of ice led to clogging flow pathways and drastically decreased the intrinsic permeability, which is significantly less than unfrozen soil with same effective porosity. This study provides a useful tool to investigate the intricate interplay between the pore-scale structure and the intrinsic permeability of frozen soils.","PeriodicalId":20066,"journal":{"name":"Physics of Fluids","volume":"1 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142258686","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

Overlapping effect of detonation driving during multi-point initiation 多点起爆期间起爆驱动的重叠效应

IF 4.6 2区工程技术

Physics of Fluids Pub Date : 2024-09-19 DOI: 10.1063/5.0231221

Yuan Li, Yuan Guo, Tao Suo, Xiaogang Li, Yuquan Wen

{"title":"Overlapping effect of detonation driving during multi-point initiation","authors":"Yuan Li, Yuan Guo, Tao Suo, Xiaogang Li, Yuquan Wen","doi":"10.1063/5.0231221","DOIUrl":"https://doi.org/10.1063/5.0231221","url":null,"abstract":"Employing multi-point initiation in warhead structures produces a detonation wave aiming warhead. Numerous studies have concentrated on enhancing the velocity and analyzing its distribution in this type of warhead. Researchers have developed formulas for the velocity distribution of asymmetrically one-line initiated warheads; however, a reliable and complete calculation method for the velocity distribution in asymmetrically two-line initiated warheads is yet to be established. A new idea is proposed and verified in this work: the velocity distribution for the asymmetric two-line initiation can be derived from that of the one-line initiation. Initial efforts include conducting experimentally verified numerical modeling to examine the propagation and interaction of detonation waves in asymmetrically two-line initiated warheads. Subsequently, using the principle of independent propagation, a model is formulated to use the velocity distribution from asymmetric one-line initiation to predict that of asymmetric two-line initiations. Finally, arena tests are performed to corroborate the overlapping model. This research can provide valuable insights for lethality assessment, protection design, and security analysis.","PeriodicalId":20066,"journal":{"name":"Physics of Fluids","volume":"3 3 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142258688","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

Computational investigation of both geometric and fluidic compressible turbulent thrust vectoring, using a Coanda based nozzle 利用科恩达喷嘴对几何和流体可压缩湍流推力矢量进行计算研究

IF 4.6 2区工程技术

Physics of Fluids Pub Date : 2024-09-19 DOI: 10.1063/5.0222070

Alireza Nayebi, Mohammad Taeibi Rahni

引用次数: 0

Directional self-migration of droplets on an inclined surface driven by wettability gradient 由润湿梯度驱动的液滴在倾斜表面上的定向自迁移

IF 4.6 2区工程技术

Physics of Fluids Pub Date : 2024-09-19 DOI: 10.1063/5.0228546

Ying Zhang, Shuting Zhao, Yao Liu, Deji Sun, Zhaoqing Ke, Yuan Tian

{"title":"Directional self-migration of droplets on an inclined surface driven by wettability gradient","authors":"Ying Zhang, Shuting Zhao, Yao Liu, Deji Sun, Zhaoqing Ke, Yuan Tian","doi":"10.1063/5.0228546","DOIUrl":"https://doi.org/10.1063/5.0228546","url":null,"abstract":"In the current study, the anti-gravity directional self-migration of droplets on an inclined surface driven by wettability gradient (ω) was investigated using a front-tracking method. A unified mechanical model of droplet motion on an inclined wettability gradient wall was derived, considering the driving force generated by ω (Fd), gravity (G), and flow resistance (Ff). The model demonstrates that ω, G, and inclination angle (α) are key parameters affecting droplet motion. By varying ω, Bond number (Bo), and α, the droplet dynamic characteristics were analyzed, and a real-time Capillary number (Ca) was introduced to measure the droplet migration speed. The results indicate that a larger ω generates a greater Fd, leading to faster migration and more pronounced spreading. When the ratio of the channel width to the droplet diameter is 0.7, the droplet can cross three regions, obtaining double Fd, and Ca curve exhibits a bimodal structure. When the ratio of the channel width to the droplet diameter is 1.2, the droplet slides and spreads in the middle region without ω, resulting in a trimodal Ca curve. A larger Bo implies a stronger gravity effect, reducing the net driving force for upward migration and slowing the migration speed. At α=30° and ω=0.54, Bo reaches its critical value at 0.5, where G exceeds Fd, causing the droplet to slide downward along the wall. α affects droplet motion by controlling the gravitational component along the wall (Gx). A larger α results in a smaller net driving force for upward migration, reducing the migration speed.","PeriodicalId":20066,"journal":{"name":"Physics of Fluids","volume":"11 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142258685","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

Study on the Karman gait kinematics of an airfoil in an asymmetrical vortex street 非对称涡街中机翼的卡曼步态运动学研究

IF 4.6 2区工程技术

Physics of Fluids Pub Date : 2024-09-18 DOI: 10.1063/5.0228852

Wenbo Wu, Runpeng Gu, Zhongming Hu, Yuankun Sun

{"title":"Study on the Karman gait kinematics of an airfoil in an asymmetrical vortex street","authors":"Wenbo Wu, Runpeng Gu, Zhongming Hu, Yuankun Sun","doi":"10.1063/5.0228852","DOIUrl":"https://doi.org/10.1063/5.0228852","url":null,"abstract":"To understand fish swimming behavior in unsteady flows, this paper introduces the Kármán gait model to numerically investigate the hydrodynamics of fish-like swimming in an asymmetric vortex environment, specifically the P + S mode (a pair of vortices are shed from one side of the cylinder and a single vortex from the other side during one oscillation period) created by an oscillating cylinder. The immersed boundary method is employed to model both the fish-like airfoil and the vibrating cylinder. Through simulations across a broad range of controlling parameters, we analyze the advancement efficiency of the airfoil in the P + S mode, the force coefficients, Fourier spectra of hydrodynamic forces, and the interactions between the airfoil and vortices. Our findings reveal that the fundamental phase Φ0 is crucial, as it directly influences the airfoil's position relative to the vortex and affects the forces exerted. Other parameters play a secondary role, primarily reinforcing the effect of the fundamental phase on airfoil–vortex interactions. Furthermore, the vortex pair boosting effect, unique to the P + S mode, enhances the airfoil's thrust and swimming efficiency. The wake environment behind the airfoil is also vital for maximizing benefits from the P + S mode. When the fundamental mode fs, indicative of the airfoil's ability to extract energy from vortices, dominates the Fourier spectra of hydrodynamic forces, it supports the airfoil's motion in the P + S mode. Conversely, when the first harmonic mode 2fs dominates the drag spectrum, it hinders propulsion by reducing the airfoil's thrust in the swimming direction.","PeriodicalId":20066,"journal":{"name":"Physics of Fluids","volume":"1 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142258787","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

Performance prediction and design optimization of a transonic rotor based on deep transfer learning 基于深度迁移学习的跨音速转子性能预测与设计优化

IF 4.6 2区工程技术

Physics of Fluids Pub Date : 2024-09-18 DOI: 10.1063/5.0221767

Hefang Deng, Songan Zhang, Kailong Xia, Xiaoqing Qiang, Mingmin Zhu, Jinfang Teng

{"title":"Performance prediction and design optimization of a transonic rotor based on deep transfer learning","authors":"Hefang Deng, Songan Zhang, Kailong Xia, Xiaoqing Qiang, Mingmin Zhu, Jinfang Teng","doi":"10.1063/5.0221767","DOIUrl":"https://doi.org/10.1063/5.0221767","url":null,"abstract":"Deep transfer learning is frequently employed to address the challenges arising from limited or hard-to-obtain training data in the target domain, but its application in axial compressors has been scarcely explored thus far. In this paper, a multi-objective optimization framework of a transonic rotor is established using deep transfer learning. This framework first pre-trains deep neural networks based on the peak efficiency condition of 100% design speed and then fine-tunes the networks to predict the performance of off-design conditions based on the small training dataset. Finally, the design optimization of the transonic rotor is carried out through non-dominated sorting genetic algorithm II. Compared to neural networks that are trained directly, transfer learning models can achieve higher prediction accuracy, particularly in scenarios with small training datasets. This is because the pre-trained weights can offer a better initial state for transfer learning models. Moreover, transfer learning models can use fewer samples to obtain an approximate Pareto front, making the optimized rotor increase the isentropic efficiency at both peak efficiency and high loading conditions. The efficiency improvement of the optimized rotor is attributed to the reduction of the loss associated with the tip leakage flow by adjusting the tip loading distribution. Overall, this study fully demonstrates the effectiveness of transfer learning in predicting compressor performance, which provides a promising approach to solving high-cost compressor design problems.","PeriodicalId":20066,"journal":{"name":"Physics of Fluids","volume":"39 3 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142258718","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 novel variable-coefficient extended Davey–Stewartson system for internal waves in the presence of background flows 存在背景流情况下的新型可变系数扩展戴维-斯图沃特森内波系统

IF 4.6 2区工程技术

Physics of Fluids Pub Date : 2024-09-18 DOI: 10.1063/5.0219224

Jun-Chao Sun, Xiao-Yan Tang, Yong Chen

{"title":"A novel variable-coefficient extended Davey–Stewartson system for internal waves in the presence of background flows","authors":"Jun-Chao Sun, Xiao-Yan Tang, Yong Chen","doi":"10.1063/5.0219224","DOIUrl":"https://doi.org/10.1063/5.0219224","url":null,"abstract":"We propose a novel variable-coefficient Davey–Stewartson type system for studying internal wave phenomena in finite-depth stratified fluids with background flows, where the upper- and lower-layer fluids possess distinct velocity potentials, and the variable-coefficient terms are primarily controlled by the background flows. This realizes the first application of variable-coefficient DS-type equations in the field of internal waves. Compared to commonly used internal wave models, this system not only describes multiple types of internal waves, such as internal solitary waves, internal breathers, and internal rogue waves, but also aids in analyzing the impact of background flows on internal waves. We provide the influence of different background flow patterns on the dynamic behavior and spatial position of internal waves, which contribute to a deeper understanding of the mechanisms through which background flows influence internal waves. Furthermore, the system is capable of capturing variations in the velocity potentials of the upper and lower layers. We discover a connection between internal waves under the influence of background flows and velocity potentials. Through the variations in velocity potentials within the flow field, the dynamic behaviors of internal waves can be indirectly inferred, their amplitude positions located, and different types of internal waves distinguished. This result may help address the current shortcomings in satellite detection of internal wave dynamics and internal rogue waves.","PeriodicalId":20066,"journal":{"name":"Physics of Fluids","volume":"17 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142258721","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

Influence of different factors on gap breakdown process with hot electrode and high temperature gas medium in low voltage circuit breaker chamber based on particle-in-cell/Monte-Carlo collision simulation 基于粒子入室/蒙特卡洛碰撞模拟的低压断路器室中热电极和高温气体介质对间隙击穿过程不同因素的影响

IF 4.6 2区工程技术

Physics of Fluids Pub Date : 2024-09-18 DOI: 10.1063/5.0207871

Lijun Wang, Runze Hu, Zhuo Chen, Zhiwei Wang, Yile Wang

{"title":"Influence of different factors on gap breakdown process with hot electrode and high temperature gas medium in low voltage circuit breaker chamber based on particle-in-cell/Monte-Carlo collision simulation","authors":"Lijun Wang, Runze Hu, Zhuo Chen, Zhiwei Wang, Yile Wang","doi":"10.1063/5.0207871","DOIUrl":"https://doi.org/10.1063/5.0207871","url":null,"abstract":"Different factors such as gas composition inside the low voltage circuit breaker (LVCB) chamber and the residual plasma in the post-arc stage affect the breakdown process, which in turn affects the breaking capacity of LVCBs. In this paper, the effects of non-parallel electrode structure, gas temperature and pressure, electrode temperature, and gap distance on gap breakdown of hot electrode under high temperature gas conditions were studied, for which a particle-in-cell/Monte-Carlo collision simulation model has been established, which takes into account the effects of high-temperature gas components, cathode electron thermal emission, electron collision ionization and other effects, and simulation studies have been conducted. The simulation results show that the increase in gap gas temperature, the decrease in air pressure, and the increase in electrode temperature will lead to the gap breakdown more easily. With the increase in the gap length, the breakdown voltage increases, but the average electric field intensity required for breakdown decreases. In the non-parallel electrode structure, the breakdown occurs first at the position with the shortest gap distance, then the cathode sheath forms and extends along the electrode surface to other areas, and finally, the entire gap breaks down.","PeriodicalId":20066,"journal":{"name":"Physics of Fluids","volume":"101 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142258781","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

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":"16 1","pages":""},"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