Physics of Fluids最新文献_第3页

Intelligent reconstruction of unsteady combustion flow field of scramjet based on physical information constraints 基于物理信息约束的扰流喷气式飞机非稳态燃烧流场智能重构

Physics of Fluids Pub Date : 2024-07-01 DOI: 10.1063/5.0217991

Xue Deng, Mingming Guo, Yi Zhang, Ye Tian, Jingrun Wu, Heng Wang, Hua Zhang, Jialing Le

{"title":"Intelligent reconstruction of unsteady combustion flow field of scramjet based on physical information constraints","authors":"Xue Deng, Mingming Guo, Yi Zhang, Ye Tian, Jingrun Wu, Heng Wang, Hua Zhang, Jialing Le","doi":"10.1063/5.0217991","DOIUrl":"https://doi.org/10.1063/5.0217991","url":null,"abstract":"To alleviate the problem of high-fidelity data dependence and inexplicability in pure data-driven neural network models, physical informed neural networks (PINNs) provide a new learning paradigm. This study constructs an efficient, accurate, and robust PINN framework for predicting unsteady combustion flow fields based on Navier–Stokes (NS) equation constraints. To achieve fast prediction of a multi-physical field in a scramjet combustion chamber, we propose a U-shaped residual neural network model based on feature information fusion. The model uses a residual neural network module as the backbone, uses jump connection to improve model generalization, and uses the U-shaped structure to fuse the receptive field features with different scales to enhance the feature expression ability of the model. To prevent improper assumptions from leading to wrong method constraints, we consider the flow characteristic mechanism of each physical field to constrain the neural network and verify its accuracy through numerical simulation of the unsteady flow field in the scramjet combustor with Mach number (Ma) 2.0. This method can accurately predict the multi-physical field of unsteady turbulent combustion based on the time, space, Ma and turbulent eddy viscosity coefficients of a small number of samples. Specially, the proposed physical driven and data driven fusion proxy model can predict the unsteady combustion flow field in milliseconds. It has important reference value to solve the problem of low calculation efficiency of a traditional numerical simulation method of a combustion process.","PeriodicalId":509470,"journal":{"name":"Physics of Fluids","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141703505","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}

引用次数: 0

Pinch-off dynamics of an electrohydrodynamic tip streaming jet transforming into the microdroplet 电流体动力尖端流射流转化为微滴的掐断动力学

Physics of Fluids Pub Date : 2024-07-01 DOI: 10.1063/5.0215316

Guozhen Wang, Wei Chen, Jiankui Chen, Chao Hu, Hao Chen, Zhouping Yin

{"title":"Pinch-off dynamics of an electrohydrodynamic tip streaming jet transforming into the microdroplet","authors":"Guozhen Wang, Wei Chen, Jiankui Chen, Chao Hu, Hao Chen, Zhouping Yin","doi":"10.1063/5.0215316","DOIUrl":"https://doi.org/10.1063/5.0215316","url":null,"abstract":"The drop-on-demand electrohydrodynamic (EHD) printing is promising for manufacturing high-resolution dot arrays. Such dot fabrication is commonly achieved through two printing modes (jet/droplet mode), i.e., continuous jet directly flying to or broken jet induced droplet depositing in the substrate. The droplet mode commonly has a higher printing frequency than the jet mode, indicating the droplet mode's advantage in drop-on-demand EHD printing. However, most research on EHD printing focuses on the jet mode, which causes the mechanism of droplet production through jet pinch-off remains unclear. This study employs an arbitrary Lagrangian–Eulerian method capable of getting a sharp interface to reveal the pinch-off mechanism. First, the development of a tip streaming from a meniscus to the pinch-off is analyzed. It is found that the high pressure at the neck is the main reason for the pinch-off of the jet into the droplet. Second, the EHD phase diagram in the parameter space of We–Cae is plotted, where We is the Weber number and Cae is the electric capillary number. Finally, the important influences of the charge relaxation on the EHD tip streaming jet's breakup behavior and the generated droplets' properties are revealed. Evolutions of the droplet's properties, including radius, velocity, and charge, with varying charge relaxation parameters are offered. These properties of the droplet show their relationships with extreme values as a function of the charge relaxation parameter. This work can serve as the theoretical basis for tuning the EHD printing manufacturing performance.","PeriodicalId":509470,"journal":{"name":"Physics of Fluids","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141711094","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}

引用次数: 0

Concentration and cavitation phenomena of Riemann solutions for the generalized Chaplygin gas equations under the flux approximation 通量近似条件下广义查普利金气体方程黎曼解的浓缩和空化现象

Physics of Fluids Pub Date : 2024-07-01 DOI: 10.1063/5.0216565

Zhiqiang Shao, Meixiang Huang

{"title":"Concentration and cavitation phenomena of Riemann solutions for the generalized Chaplygin gas equations under the flux approximation","authors":"Zhiqiang Shao, Meixiang Huang","doi":"10.1063/5.0216565","DOIUrl":"https://doi.org/10.1063/5.0216565","url":null,"abstract":"In this paper, we investigate the concentration and cavitation phenomena of Riemann solutions for the generalized Chaplygin gas equations in the presence of flux approximation. The concentration and cavitation are fundamental and physical phenomena in fluid dynamics, which can be mathematically described by delta shock waves and vacuums (or constant density states), respectively. The main objective of this paper is to rigorously investigate the formation of delta shock waves and constant density states and observe the concentration and cavitation phenomena. First, the Riemann problem for the generalized Chaplygin gas equations under the flux approximation is solved constructively. Although the system is strictly hyperbolic and its two characteristic fields are genuinely nonlinear, the delta shock wave arises in Riemann solutions. The formation of mechanism for delta shock wave is analyzed, that is, the 1-shock wave curve and the 2-shock wave curve do not intersect each other in the phase plane. Second, it is rigorously proved that, as the pressure vanishes, the Riemann solutions for the generalized Chaplygin gas equations under the flux approximation tend to the two kinds of Riemann solutions to the transport equations in zero-pressure flow under the flux approximation, which include a delta shock wave formed by a weighted δ-measure and a constant density state.","PeriodicalId":509470,"journal":{"name":"Physics of Fluids","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141691975","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}

引用次数: 0

Collaborative optimization of two-dimensional convergent divergent exhaust system based on Kriging model 基于克里金模型的二维收敛发散排气系统协同优化

Physics of Fluids Pub Date : 2024-07-01 DOI: 10.1063/5.0215032

Lan Bo, Qiang Wang, Haiyang Hu

{"title":"Collaborative optimization of two-dimensional convergent divergent exhaust system based on Kriging model","authors":"Lan Bo, Qiang Wang, Haiyang Hu","doi":"10.1063/5.0215032","DOIUrl":"https://doi.org/10.1063/5.0215032","url":null,"abstract":"In order to enhance the performance of the two-dimensional exhaust system during high-speed cruising and enhance aircraft survivability against infrared-guided weaponry, this study undertakes a systematic optimization of the geometric and thermodynamic parameters governing the two-dimensional exhaust system. The optimization objectives encompass augmenting both the discharge coefficient and the thrust coefficient of the nozzle while concurrently mitigating the infrared radiation intensity emanating in the tail direction. Imposing limitations on the infrared radiation intensity across diverse detection angles, the study further imposes constraints on the thrust efficiency and deflection efficiency of the thrust vectoring nozzle subsequent to a 15° deflection. Such measures ensure the maintenance of optimal stealth capabilities across all detection angles while preserving the unhampered thrust vectoring performance of the nozzle. This study employs the optimal Latin hypercube method and Kriging surrogate models in conjunction with collaborative optimization techniques to address multidisciplinary design optimization challenges. Comparative analyses with the initial design revealed significant enhancements: up to a 2.88% increase in the discharge coefficient, a maximum 0.53% increase in the thrust coefficient, and a notable reduction of up to 17.09% in tail direction dimensionless infrared radiation intensity, validating the effectiveness of the optimized exhaust system design.","PeriodicalId":509470,"journal":{"name":"Physics of Fluids","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141714429","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}

引用次数: 0

Effects of real gas models on the wave dynamics and refrigeration of gas wave rotor 真实气体模型对气浪转子波动力学和制冷的影响

Physics of Fluids Pub Date : 2024-07-01 DOI: 10.1063/5.0215325

Yihui Zhou, Feng Gao, Zhijun Liu, Dapeng Hu

{"title":"Effects of real gas models on the wave dynamics and refrigeration of gas wave rotor","authors":"Yihui Zhou, Feng Gao, Zhijun Liu, Dapeng Hu","doi":"10.1063/5.0215325","DOIUrl":"https://doi.org/10.1063/5.0215325","url":null,"abstract":"The gas wave rotor was usually designed and performed on the ideal gas model. However, the real gas effect could not be ignored anymore under high-pressure ratio conditions. In this study, for the first time, a two-dimensional computational model of a double-opening gas wave refrigerator (GWR) using a multi-parameter Benedict–Webb–Rubin equation of state is established and the influence of the real gas effect on gas wave dynamics and energy transfer processes in the GWR with discontinuous boundary conditions is thoroughly investigated. The numerical results show that the wave dynamics of the ideal gas and the real gas are similar under different operating conditions, but compression waves and expansion waves in real gas obviously lag behind the ideal gas. In addition, the low-temperature real gas is completely discharged earlier than the ideal gas and the difference between them gradually increases as the pressure ratio gets higher, which benefits the GWR compact structure design and cost reduction. At the same time, the temperature of the real gas being discharged is lower than that of the ideal gas. Therefore, the refrigeration efficiency of the isentropic expansion of the real gas will be improved compared with the operation in ideal gas. The research results on the real gas effect reveal the mechanism of wave dynamics and energy transfer, providing support for the optimization design of GWR.","PeriodicalId":509470,"journal":{"name":"Physics of Fluids","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141704442","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}

引用次数: 0

Erratum: “Up, down, and round again: The circulating flow dynamics of flux-driven fractures” [Phys. Fluids 36, 036622 (2024)] 勘误："上，下，再上，再下：通量驱动裂缝的循环流动动力学" [Phys. Fluids 36, 036622 (2024)] 更正

Physics of Fluids Pub Date : 2024-07-01 DOI: 10.1063/5.0218681

C. M. Chalk, J. L. Kavanagh

引用次数: 0

Impact of microplastic pollution on breaking waves 微塑料污染对破浪的影响

Physics of Fluids Pub Date : 2024-07-01 DOI: 10.1063/5.0208507

Jotam Bergfreund, Ciatta Wobill, Frederic M. Evers, B. Hohermuth, Pascal Bertsch, Laurent Lebreton, Erich J Windhab, Peter Fischer

{"title":"Impact of microplastic pollution on breaking waves","authors":"Jotam Bergfreund, Ciatta Wobill, Frederic M. Evers, B. Hohermuth, Pascal Bertsch, Laurent Lebreton, Erich J Windhab, Peter Fischer","doi":"10.1063/5.0208507","DOIUrl":"https://doi.org/10.1063/5.0208507","url":null,"abstract":"Anthropogenic plastic waste heavily pollutes global water systems. In particular, micron-sized plastic debris can have severe repercussions for the ocean flora and fauna. Microplastics may also affect physical processes such as wave breaking, which are critical for air–sea interaction and albedo. Nevertheless, the effects of micron-sized plastic debris on geophysical processes are widely unexplored. Herein, we investigate the effect of microplastic collected from the North Pacific and a surfactant mimicking surface active materials present in the ocean on the stability of foam generated by breaking wave experiments. We found that microplastic particles increase foam stability. In particular, an increased foam height was found in a column foaming setup, while an increased foam area was observed in a laboratory-scale breaking wave channel. We propose that microplastic particles assemble at the air–water interface of foam bubbles, form aggregates, presumably decrease the liquid drainage in the liquid film, and thus change the lifetime of the liquid film and the bubble. The effect of surfactants is generally larger due to their higher surface activity but still in a range where synergistic effects can be observed. Our results suggest that microplastic could influence oceanic processes essential for air–sea interaction, sea spray formation, and albedo.","PeriodicalId":509470,"journal":{"name":"Physics of Fluids","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141710157","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}

引用次数: 0

Physics of Fluids Pub Date : 2024-07-01 DOI: 10.1063/5.0214647

V. K. Vats, D. B. Singh, Mrigendra Manjul

{"title":"Similarity solution for the magnetogasdynamic shock wave in a self-gravitating and rotating ideal gas under the influence of radiation heat flux","authors":"V. K. Vats, D. B. Singh, Mrigendra Manjul","doi":"10.1063/5.0214647","DOIUrl":"https://doi.org/10.1063/5.0214647","url":null,"abstract":"The Lie invariance method is used to analyze the one-dimensional, unsteady flow of a cylindrical shock wave in a rotating, self-gravitating, radiating ideal gas under the influence of an axial or azimuthal magnetic field, with an emphasis on adiabatic conditions. The analysis assumes a stationary environment just ahead of the shock wave and considers variations in fluid velocity, magnetic field, and density within the perturbed medium just behind the shock front. In the governing equations, the impact of thermal radiation under an optically thin limit is integrated into the energy equation. Utilizing the Lie invariance method, the set of partial differential equations governing the flow in this medium is transformed into a system of nonlinear ordinary differential equations (ODEs) using similarity variables. Two distinct cases of similarity solutions are obtained by selecting different values for the arbitrary constants associated with the generators. Among these cases, one yields similarity solutions assuming a power-law shock path and the other an exponential-law shock path. For both cases, the resulting set of nonlinear ODEs are numerically solved using the 4th-order Runge–Kutta method in MATLAB software. The article thoroughly explores the influence of various parameters, including γ (adiabatic index of the gas), Ma−2 (Alfvén–Mach number), σ (ambient density exponent), l1 (rotational parameter), and G0 (gravitational parameter) on the flow properties. The findings are visually presented to offer a comprehensive insight into the effects of these parameters.","PeriodicalId":509470,"journal":{"name":"Physics of Fluids","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141716802","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}

引用次数: 0

Enhancing smoke management in underground parking areas using jet fan systems with a focus on dead-end areas 利用射流风机系统加强地下停车场的烟雾管理，重点关注死角区域

Physics of Fluids Pub Date : 2024-07-01 DOI: 10.1063/5.0213475

Saeed Hazrati Chakheirlou, Abdolnaser Omrani, Behnam Heydari Param, Roghayyeh Motallebzadeh

{"title":"Enhancing smoke management in underground parking areas using jet fan systems with a focus on dead-end areas","authors":"Saeed Hazrati Chakheirlou, Abdolnaser Omrani, Behnam Heydari Param, Roghayyeh Motallebzadeh","doi":"10.1063/5.0213475","DOIUrl":"https://doi.org/10.1063/5.0213475","url":null,"abstract":"This study delves into the utilization of jet fans in underground parking structures for smoke management during fires, with a specific focus on enhancing smoke control near critical areas adjacent to dead-end sections through innovative jet fan designs. Through the analysis of airflow patterns and computational fluid dynamic simulations, the research aims to effectively contain smoke and prevent its dispersion to unaffected zones. Findings underscore the significance of parking layout designs in ventilation strategies and soot dispersion rates. Altering the downward orientation of the jet fan outlet results in a notable portion of smoke being confined within the parking facility. Additionally, widening the jet fan outlet, as proposed in the design, can enhance smoke evacuation in all directions. Two hazard detection scenarios were executed within the parking structure following the British standard (BS), with one scenario simulated as a fire ignition source. The chosen scenario considers all escape routes and evacuation procedures within the underground parking area based on architectural specifications. By employing OpenFOAM software with the buoyantBoussinesqPimpleFOAM solver, the study assesses the efficacy of this approach, achieving a reduction in airflow irregularities of over 30%. It also provides valuable insights for designers to refine their comprehension of jet fan design, recommending tailored designs for specific zones. This research offers practical guidance for designers to optimize jet fan configurations for effective smoke control in underground parking facilities.","PeriodicalId":509470,"journal":{"name":"Physics of Fluids","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141694129","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}

引用次数: 0

Direct numerical simulations of pure and partially cracked ammonia/air turbulent premixed jet flames 纯氨/空气湍流预混合喷射火焰和部分裂解氨/空气湍流预混合喷射火焰的直接数值模拟

Physics of Fluids Pub Date : 2024-07-01 DOI: 10.1063/5.0215258

Tingquan Tian, Haiou Wang, K. Luo, Jianren Fan

{"title":"Direct numerical simulations of pure and partially cracked ammonia/air turbulent premixed jet flames","authors":"Tingquan Tian, Haiou Wang, K. Luo, Jianren Fan","doi":"10.1063/5.0215258","DOIUrl":"https://doi.org/10.1063/5.0215258","url":null,"abstract":"Ammonia has been identified as a promising fuel to diminish greenhouse gas emission. However, ammonia combustion presents certain challenges including low reactivity and high NO emission. In the present study, three-dimensional direct numerical simulations (DNS) of ammonia/air premixed slot jet flames with varying Karlovitz numbers (Ka) and cracking ratios were performed. Three cases were considered, including two pure ammonia/air flames with different turbulence intensities and one partially cracked ammonia/air flame with high turbulence intensity. The effects of turbulence intensity and partial ammonia cracking on turbulence–flame interactions and NO emission characteristics of the flames were investigated. It was shown that the turbulent flame speed is higher for the flames with high turbulence intensity. In general, the flame displacement speed is negatively correlated with curvature in negative curvature regions, while the correlation is weak in the positive curvature regions for highly turbulent flames. Most flame area is consumed in negatively curved regions and produced in positively curved regions. It was found that the NO mass fraction is higher in the flame with partial ammonia cracking compared to the pure ammonia/air flames. The NO pathway analysis shows that the NH → NO pathway is enhanced, while the NO consumption pathway is suppressed in the partially cracked ammonia/air flame. The NO mass fraction is higher in regions of negative curvature than positive curvature. Interestingly, the NO mass fraction is found to be negatively correlated with the local equivalence ratio, which is consistent in both the DNS and the corresponding laminar premixed flames.","PeriodicalId":509470,"journal":{"name":"Physics of Fluids","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141691319","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}

引用次数: 0