International Journal of Heat and Fluid Flow最新文献

{"title":"Prediction of turbulent flow in a volute-type centrifugal pump at design and part-load conditions: LES vs. URANS","authors":"Beomjun Kye,&nbsp;Haecheon Choi","doi":"10.1016/j.ijheatfluidflow.2026.110635","DOIUrl":"10.1016/j.ijheatfluidflow.2026.110635","url":null,"abstract":"<div><div>Turbulent flows in a volute-type centrifugal pump at design and part-load conditions are investigated using both large eddy simulation (LES) and simulation with unsteady Reynolds-averaged Navier–Stokes equations (URANS). The Reynolds number based on the blade tip velocity and radius of the impeller blade is 1,740,000. The head coefficient and efficiency of the pump are accurately predicted by LES in close agreement with experimental data, whereas URANS shows noticeable discrepancies. LES successfully captures small-scale vortical structures above the impeller blade suction surface, strong vortices shed from the blade trailing edge, and their subsequent interactions within the volute and near the tongue region. Furthermore, flow separation and swirl along the discharge pipe are well reproduced by LES. In contrast, URANS fails to resolve small-scale vortices throughout the flow field and to capture the swirl in the discharge pipe, leading to inaccurate predictions of pump performance.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"121 ","pages":"Article 110635"},"PeriodicalIF":4.8,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148934417","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A selective frequency damping method for Lattice-Boltzmann solvers","authors":"Jérôme Jacob,&nbsp;Samuel Carré,&nbsp;Christophe Friess","doi":"10.1016/j.ijheatfluidflow.2026.110621","DOIUrl":"10.1016/j.ijheatfluidflow.2026.110621","url":null,"abstract":"<div><div>The present study deals with the issue of convergence in Lattice-Boltzmann computations of turbulent flows using the Reynolds-Averaged Navier–Stokes (RANS) approach. A method to enforce the convergence toward the average flow is proposed. It is inspired from the work of Å kervik et al., (2006), regarding selective frequency damping (SFD). Preliminary results of the method are shown. The studied cases are the flow around a cylinder at <span><math><mrow><mi>R</mi><mi>e</mi><mo>=</mo><mn>140000</mn></mrow></math></span>, the flow around the 30P30N airfoil at <span><math><mrow><mi>R</mi><mi>e</mi><mo>=</mo><mn>1.7</mn><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>6</mn></mrow></msup></mrow></math></span> and the flow around the NACA23012 at <span><math><mrow><mi>R</mi><mi>e</mi><mo>=</mo><mn>1.88</mn><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>6</mn></mrow></msup></mrow></math></span>. The overall agreement between forced flow and unforced, time-averaged flow, is encouraging, with only local significant discrepancies in velocity and pressure.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"121 ","pages":"Article 110621"},"PeriodicalIF":4.8,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148934496","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Coupled internal and external flow on cooling and heat transfer over a turbine blade trailing-edge cutback slot under high-speed conditions","authors":"Yuan Li,&nbsp;Yu Rao,&nbsp;Yuli Cheng","doi":"10.1016/j.ijheatfluidflow.2026.110658","DOIUrl":"10.1016/j.ijheatfluidflow.2026.110658","url":null,"abstract":"<div><div>This study examines the internal heat transfer and external cooling characteristics of a trailing-edge cutback slot equipped with an upstream pin fin under high-speed conditions. The pressure ratio varied from 1.10 to 1.50 and the mainstream Mach number at the throat was maintained at 0.65. The internal heat transfer distributions were obtained using transient thermochromic liquid crystal measurements, whereas transient infrared thermography was employed to evaluate the adiabatic film cooling effectiveness and relative heat transfer coefficient on the external cutback surface. Numerical simulations based on the LES method were further conducted to reveal the flow mechanisms. For the Base model, raising the pressure ratio leads to a monotonic increase in the Nusselt number inside the cutback slot, and the enhanced heat transfer is concentrated at the inlet contraction and near the slot sides. On the external cutback surface, the Base model preserves an almost continuous coolant film. After introducing the upstream pin fin, at a low pressure ratio of 1.10, the internal Nusselt number is increased by approximately 22%. However, the internal Nusselt number decreases markedly as the pressure ratio rises, reaching only about 47% of that of the Base model at the pressure ratio of 1.50. The enhanced heat transfer region is confined between the pin fin and the inlet contraction. Furthermore, the pin fin increases the relative heat transfer coefficient but reduces the adiabatic film cooling effectiveness on the cutback surface. The LES results show that the pin fin induces a streamwise vortex and a downstream wake region. At low pressure ratios, vortex-induced disturbance enhances internal heat transfer. At higher pressure ratios, however, the wake-induced influence on the internal slot flow becomes more pronounced. Together with the enhanced flow blockage, this effect dominates the downstream region and weakens the overall internal heat transfer. On the cutback surface, the developing streamwise vortex strengthens the coolant-mainstream mixing and increases the convective heat transfer intensity, while disturbing the coolant-film coverage.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"121 ","pages":"Article 110658"},"PeriodicalIF":4.8,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148935119","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A numerical study on air-side heat transfer enhancement and outlet temperature uniformity improvement of fin-tube heat exchanger","authors":"Li Li,&nbsp;Haojian Gao,&nbsp;Xuemei Lin,&nbsp;Keqing Zheng,&nbsp;Yuezeng Chen,&nbsp;Zhiguo Qu","doi":"10.1016/j.ijheatfluidflow.2026.110642","DOIUrl":"10.1016/j.ijheatfluidflow.2026.110642","url":null,"abstract":"<div><div>Many industrial processes have strict temperature uniformity requirements. This work aims to enhance air-side heat transfer performance and improve outlet temperature uniformity of fin-tube heat exchanger simultaneously. Non-uniform fin design and additional mixing tubes are proposed as potential strategies and their feasibilities are validated via numerical investigations. Differences in the underlying mechanisms of the proposed strategies are analyzed based on the comparisons of flow patterns and temperature distributions. The enhanced heat transfer performance of non-uniform fin design is attributed to the increased heat transfer area and decreased airflow velocity in pre-tube section and the accelerated airflow in post-tube section. Meanwhile, the additional mixing tubes could reduce the wake region of the adjacent copper tube in front of the mixing tube and increase the airflow velocity around the adjacent copper tube after the mixing tube. In the heat exchanger design, these two strategies can be utilized together to obtain a better heat transfer effect via combined effect of these two mechanisms. Further, effects of two key parameters, including outer diameter of the mixing tube and width of the first sub-section in pre-tube section, are examined. Increased outer diameter of mixing tube and decreased first sub-section width in pre-tube section are conducive to heat transfer performance of fin-tube heat exchanger. Considering the balance between heat transfer and flow resistance, the suggested mixing tube diameter and first sub-section width in pre-tube section within the tested cases are 4 mm and 1 mm, respectively.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"121 ","pages":"Article 110642"},"PeriodicalIF":4.8,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148853930","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental study on thermal-hydraulic characteristics of a multi-channel natural circulation boiling loop","authors":"Zehui Li,&nbsp;Pengfei Ma,&nbsp;Haifeng Wang,&nbsp;Ronglin Zhong,&nbsp;Tianyang Peng,&nbsp;Wenxin Wei,&nbsp;T. Lin","doi":"10.1016/j.ijheatfluidflow.2026.110553","DOIUrl":"10.1016/j.ijheatfluidflow.2026.110553","url":null,"abstract":"<div><div>In this study, a boiling natural circulation loop (BNCL) experimental system with four parallel channels was established based on the evaporative cooling configuration of a 20 MW large offshore wind generator. Two typical flow modes were observed during the experiments. Under low heating power and high subcooling conditions, the BNCL exhibited an intermittent circulation mode, in which multiple boiling states appeared within one circulation cycle. Under high heating power and low subcooling conditions, the BNCL exhibited a continuous circulation mode, in which the boiling state was dominated by large-scale and fully developed boiling. The Fast Fourier Transform (FFT) results show that, in the intermittent circulation mode, the BNCL oscillations are characterized by low frequency and high amplitude, and the dominant frequency increases with increasing heating power. Continuous Wavelet Transform (CWT) further reveals the broadband flowrate pulsation characteristics caused by intermittent boiling. The FFT and CWT results consistently indicate that intermittent boiling induced by the combined effects of low heating power and high subcooling is the main oscillation mechanism in the BNCL. In contrast, in the continuous circulation mode, the BNCL exhibits dense, temporally irregular, high-frequency and low-amplitude oscillations in the high-frequency region. This behavior may be attributed to the intense thermodynamic motion associated with fully developed boiling under high heating power and low subcooling conditions. In addition, Multivariate Variational Mode Decomposition (MVMD) was used to effectively extract the low-frequency component of the BNCL, although the decomposition quality decreased in the continuous circulation mode under high heating power. This study provides experimental insights into the dynamic flow behavior and inter-channel coupling of horizontal multi-channel BNCLs, offering guidance for the design and optimization of large-scale evaporative cooling systems.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"121 ","pages":"Article 110553"},"PeriodicalIF":4.8,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148934492","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"CFD analysis of thermohydraulic characteristics and entropy generation in streamlined pin-fin heat sinks and multi-objective optimization using RSM and NSGA-II","authors":"Minh Ha Nguyen,&nbsp;Minh Phu Nguyen,&nbsp;Le Minh Nhut,&nbsp;Luan Nguyen Thanh","doi":"10.1016/j.ijheatfluidflow.2026.110640","DOIUrl":"10.1016/j.ijheatfluidflow.2026.110640","url":null,"abstract":"<div><div>This study focuses on analyzing the thermohydraulic characteristics and entropy generation (EG) in a streamlined pin–fin heat sink. Three different streamlined profiles were investigated to evaluate the effect of pin–fin shape. The profiles were compared based on both heat transfer and flow resistance. The tear-ellipse configuration exhibited the highest Nusselt number while maintaining a low friction factor by reducing the wake zone and enhancing flow mixing. Therefore, this configuration was selected for further detailed analysis of the thermohydraulic characteristics and EG. The effects of Reynolds number (Re = 8,558 − 17,115), pin–fin height (H = 42 − 48 mm), and pin–fin aspect ratio (e = 0.55 − 0.75) were analyzed. The results show that the Nusselt number increases and total EG decreases with increasing Re, decreasing e, or increasing H. Thermal EG predominates over frictional EG throughout the entire domain under investigation. Finally, RSM-based multi-objective optimization using NSGA-II is performed to maximize thermohydraulic performance (THP) and minimize entropy generation ratio (EGR), followed by LINMAP to identify the most suitable compromise solution from the Pareto front. The optimal result was identified at Re = 14,749.5, e = 0.55, and H = 48 mm, yielding predicted THP and EGR values of 1.4374 and 0.8297, respectively. Compared with the reference configuration, the numerical results show that Nusselt number increased by 34.8% and total EG (S_total) decreased by 17.1%. These results provide useful insights for designing heat sinks with streamlined pin-fins that achieve high thermohydraulic performance and low irreversible characteristics.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"121 ","pages":"Article 110640"},"PeriodicalIF":4.8,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148853928","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Calibration of CFD boiling model parameters of narrow-channel flow using machine learning and genetic algorithms","authors":"Yujing Du,&nbsp;Yang He,&nbsp;Ping Zhou,&nbsp;Junda Liu,&nbsp;Dongling Wu,&nbsp;Yanpo Song,&nbsp;Bin Liu,&nbsp;Liu Liu,&nbsp;Jinrun Hu","doi":"10.1016/j.ijheatfluidflow.2026.110652","DOIUrl":"10.1016/j.ijheatfluidflow.2026.110652","url":null,"abstract":"<div><div>To enhance the accuracy of the boiling heat transfer model for the narrow-channel flow boiling system, three parameters are calibrated, involving the single-phase heat flux multipliers <em>M_sp</em> and nucleation-boiling heat flux multipliers <em>M_nb</em> in Chen model as well as mass transfer coefficient <em>r</em> in Lee model. Their sensitivity is analyzed based on the single parameter simulation and range analysis method, and Mnb has little impact on the boiling heat transfer process and is set to be 1. The database of the RMS of heat source wall temperature difference and the parameters <em>r</em> and <em>M_sp</em> is established, and their correlation model is created by the BP neural network model. Then, the optimal <em>r</em> of 730 and <em>M_sp</em> of 11 are searched based on the genetic algorithm. Moreover, the optimal model parameters are validated by the experiment and the simulation of different boiling models for the narrow-channel flow boiling system.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"121 ","pages":"Article 110652"},"PeriodicalIF":4.8,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148935118","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modeling of a heavy gas turbulent dispersion in simplified and real-scale urban environments","authors":"Daoming Liu,&nbsp;Saša Kenjereš","doi":"10.1016/j.ijheatfluidflow.2026.110498","DOIUrl":"10.1016/j.ijheatfluidflow.2026.110498","url":null,"abstract":"<div><div>We report recent advances in the development of a computationally efficient and accurate time-dependent RANS-based (T-RANS) method for predicting turbulent heavy-gas dispersion in complex urban environments. Two test cases were analyzed: (i) the simplified Kit Fox field-scale setup, and (ii) a realistic urban neighborhood in Beijing. In the first case, the T-RANS approach outperformed the simplified atmospheric dispersion model (SLAB), showing significantly better agreement with field measurements due to its ability to capture local flow and turbulence features within obstructed regions. The numerical robustness and computational efficiency of the method were further validated in the real-scale Beijing neighborhood, incorporating detailed building geometries and a mesh of over 100 million control volumes. By utilizing a passive-element approach to resolve complex building geometries and accounting for the buoyancy-driven effects of local gas concentrations, this method provides a high-fidelity, computationally efficient framework for predicting the temporal evolution of turbulent heavy-gas dispersion in complex built environments.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"121 ","pages":"Article 110498"},"PeriodicalIF":4.8,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148935121","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical study on the influence of ejector mixing layer growth characteristics on entrainment performance","authors":"Xiuzhi Xi,&nbsp;Long Jiang,&nbsp;Neng Gao,&nbsp;Jiarui Liu,&nbsp;Qingpu Li,&nbsp;Xiao Zhao","doi":"10.1016/j.ijheatfluidflow.2026.110645","DOIUrl":"10.1016/j.ijheatfluidflow.2026.110645","url":null,"abstract":"<div><div>The mixing layer growth characteristics are crucial for exploring the working mechanism of ejectors. This work carries out numerical simulations to investigate the effects of back pressure and nozzle position. The relationship between the mixing layer growth characteristics and the entrainment performance is investigated under the critical mode, and the mechanism behind the performance variation is analyzed. The entrainment performance and the mixing layer growth rate share the same trend. The back pressure does not alter the growth trajectory of the mixing layer. Shifting the nozzle exit position changes the structure of the mixing channel and directly affects the mixing layer growth rate. The continued mixing after flow choking is an important component that accounts for the total pressure loss. A higher mixing layer growth rate corresponds to more intense energy transfer, which matches to a higher mixed-flow sound speed and thereby increases the entrainment ratio. This study demonstrates that the mixing layer growth characteristics are closely linked to entrainment performance. The performance optimization is an external manifestation of mixing enhancement. Deepening the research on mixing layer characteristics can be an effective approach to designing high-efficiency ejectors.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"121 ","pages":"Article 110645"},"PeriodicalIF":4.8,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148853929","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An improved predictive model for forced-convective heat transfer of turbulent boundary layers with unheated length","authors":"Yu Xia,&nbsp;Wagih Abu Rowin,&nbsp;Ivan Marusic,&nbsp;Nicholas Hutchins","doi":"10.1016/j.ijheatfluidflow.2026.110463","DOIUrl":"10.1016/j.ijheatfluidflow.2026.110463","url":null,"abstract":"<div><div>This study investigates forced convective heat transfer in turbulent boundary layers with unheated starting lengths, focusing on cases where the thermal boundary layer remains thinner than the momentum boundary layer. In these regimes, the thermal layer develops as an internal layer; consequently, the thermal wake disappears and the temperature profile transitions smoothly from a restricted logarithmic region to the freestream. To address the resulting predictive discrepancies, we adopt a boundary layer evolution approach — based on conservation of momentum and energy to predict the skin friction coefficient (<span><math><msub><mrow><mi>C</mi></mrow><mrow><mi>f</mi></mrow></msub></math></span>) and the Stanton number (<span><math><mi>St</mi></math></span>). We propose a standard log–wake model and develop a physically motivated two-state model. By accounting for turbulent/non-turbulent intermittency, the two-state model allows the thermal wake to diminish naturally with decreasing heated fetch. The two-state model significantly improves <span><math><mi>St</mi></math></span> predictions, particularly in the region immediately downstream of the heating onset, outperforming standard log–wake models.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"121 ","pages":"Article 110463"},"PeriodicalIF":4.8,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148934491","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}