Statement of the problem.The problem of optimal placement of an infrared heater in enclosed spaces is considered. The main purpose of the research is to develop a mathematical model that makes it possible to determine the best parameters for installing a heater, such as mounting height and tilt angle. The density and distribution of the heat flow depend on these parameters, which has a significant impact on the heating efficiency. The study analyzes the thermal effect of the heater depending on the geometry of the room, including the height of the ceilings, the layout and the nature of the use of space. Results and conclusions.The developed mathematical model makes it possible to adapt the installation parameters of an infrared heater to specific operating conditions. The analysis showed that the precise placement of the heater contributes to an even distribution of heat, increasing the comfort of the heated space. The results obtained confirm the possibility of reducing energy consumption due to the rational distribution of heat flow. The proposed approach is applicable to both residential and industrial facilities, where the correct location of the heater plays a critical role in ensuring efficient heating.

The study presents a novel process to design lightweight, high-performance cooling manifolds for power electronics using generative design. The process begins with a baseline design that defines the constraints of the manifold with regard to the target cooling geometry and flow path. A flow optimization is then performed to optimize flow distribution and maximize convective efficiency. Once a final fluid volume is obtained, a structural optimization is conducted to minimize weight and material usage. The simulation results for the final design demonstrated a 40.1% increase in the average heat transfer coefficient, a 7.5% decrease in average chip temperature, a 76.6% improvement in temperature uniformity, and a 63.3% reduction in weight at the expense of a minimal 5.1% increase in pressure drop compared to the baseline design.

Cardiopulmonary bypass (CPB) is a well-established procedure that uses cannulae during cardiac surgery to drain and return blood. In challenging cases (e.g. aortic dissection, reoperation), peripheral cannulation in vessels such as the axillary artery are used. However, standard cannulae at these sites may inhibit blood flow to distal extremities or require grafts that increase surgical time. This study evaluates a novel, flexible-tip arterial cannula designed for bi-directional flow. A 22Fr body cannula was developed to achieve a pressure loss (ΔP) < 100mmHg and 80/20 bi-directional flow distribution between tip outlets. A full factorial design of experiments (2-levels, 4 factors: tip A-width, B-height, C-depth, D-outlet shape) was completed to evaluate sixteen cannula tip designs using benchtop hydraulic and bi-directional flow models. Prototypes were fabricated using 3D printing via stereolithography (Form 3 + , Formlabs, Somerville, MA) with a flexible (50A) cured resin. The most efficient cannula design (A - , B + , C + , D + ) achieved 4 L/min of total bi-directional flow at a ΔP of 74mmHg. The average ΔP at 4 L/min for all candidate design was 87 ± 9mmHg (range 72-100mmHg). Primary outlet flow distribution averaged 81% ± 6% (range 70-95%) at 1-5 L/min flow rates. Tip width had the greatest influence on ΔP, followed by outlet shape, depth, and their interactions, respectively. Cylindrical and prolate spheroid shaped tips outperformed spherical designs. The novel cannula demonstrated feasibility and proof-of-concept as evidenced by bi-directional flow with ΔP comparable to commercial cannulae. Future work will involve CFD modeling and pre-clinical validation (e.g. hemolysis, cadaver fit) to support development of a low-cost, clinical grade bi-directional flow cannula for peripheral CPB to reduce surgical complexity and lower risk of adverse events.

Partially completed wells pose a significant challenge in petroleum engineering because limited reservoir contact and incomplete perforation intervals complicate precise production measurement. Traditional evaluation techniques, primarily designed for fully completed wells, frequently fail to fully capture the effects of additional pressure losses, non-radial flow patterns, and the combined impact of formation damage and partial penetration. Building upon foundational concepts of skin factor and flow efficiency, recent developments integrate pressure transient testing, production logging tools, inflow performance relationships (IPR), and numerical reservoir simulation to enhance the reliability of production forecasts. Advanced methodologies—including pseudopressure distribution modeling under non-Darcy flow, coupled wellbore–reservoir simulations, and stress-validated inflow models—offer improved accuracy in predicting flow distribution, pressure profiles, and overall well productivity. This study underscores the value of merging conventional well test interpretation with modern computational approaches and digital monitoring systems. The results demonstrate that contemporary measurement and modeling strategies not only improve production estimation but also provide essential guidance for completion design and optimization in complex oil and gas reservoirs. Keywords: Partially completed wells, production measurement, skin factor, inflow performance relationship (IPR), pressure transient analysis, pseudopressure modeling, reservoir simulation, production logging, non-Darcy flow.

A high-burnup fuel management strategy to extend the fuel lifetime of spent high-temperature gas-cooled reactor (HTGR) fuel for a once-through fuel cycle had been proposed in previous research. The strategy is able to increase fuel utilization efficiency without compromising the safety and proliferation resistance features of the tristructural isotropic particle fuel. This study aims to provide quantitative insights into the potential effects of core design changes aimed to implement the strategy to directly reuse spent fuel, focusing on thermal-hydraulic performance under both steady-state operation and accident scenarios. Neutronics and thermal-hydraulic analysis have been performed using a sample core layout for the direct reuse of spent fuel. This study puts a heavier focus on the thermal-hydraulic analysis, with the neutronics analysis as a supplement to highlight the trade-offs between enhanced fuel utilization and thermal safety performance associated with the direct reuse of spent fuel in a two-region HTGR core. Results showed that simple modifications could be done to a reference HTGR core design to form a two-region core to directly reuse spent fuel assemblies without significant degradation in core performance. The fuel burnup could be increased by 10% with this design without deterioration in core safety parameters in terms of reactor kinetics. The steady-state thermal-hydraulic analysis with a simplified RELAP5-3D model showed that a two-region core could also operate at fuel temperatures similar to its reference core, which could be achieved by having a coolant flow distribution based on the power ratio between the two fuel regions. The core modifications only caused the peak fuel temperature during a depressurized loss-of–forced cooling scenario to increase by approximately 60°C higher compared to its reference core.

Abstract Dynamic gravel bed rivers experience frequent changes in channel position and flow distribution between branches, which can alter the location and extent of flooding. Changes in flow routing can significantly impact livelihoods, habitats and infrastructure in adjacent floodplains. Here, we test whether variations in seasonal discharge patterns cause instability in channel position and flow distribution in a gravel bed river system around a major channel bifurcation. Satellite images of the Karnali River, Nepal, were assessed over a 30‐year period to identify changes in channel position and flow partitioning downstream of the bifurcation. These observations were compared with daily discharge records to establish whether the sequencing of peak monsoonal flows coincided with geomorphic changes in the river. Changes to flow partitioning trends were consistently preceded by monsoon seasons with two large peak flows, suggesting a history‐dependent threshold in the channels. To explain this observation, we use grain‐size data from gravel bars that reveal variable grain clustering and bed armoring across the channel network. We propose that two high discharges are needed to transition between phases of bifurcation stability or instability, where the first event acts to break down the bed armor layer, allowing the second high flow to drive enlargement/closure of branches and reworking of the bed. Our findings suggest that flow sequencing is an important driver in flow distribution and stability at bifurcations in gravel bed rivers. Although the focus is on Himalayan rivers, the findings may be of relevance in other areas that experience changing seasonal flood regimes.

Experimental investigation of flow distribution in enhanced geothermal systems with deep eutectic solvent

Microfluidics enable high-precision and cost-effective processing of biological and chemical substances. However, designing and fabricating microfluidic chips typically requires substantial expertise and numerous design iterations, posing considerable barriers to entry for nonexperts. We introduce μFluidicGenius (μFG), an open-access, machine learning (ML)–augmented design tool that enables nonexpert users to rapidly create functional microfluidic circuits. Users simply define the spatial placement of reservoirs, specify the channel connections between them, and assign desired flow rates through this layout. Leveraging a hybrid algorithmic framework that integrates ML models with mathematical modeling, μFG automatically generates spatially coded maze structures that implement the precise fluidic resistances needed to meet the target flow distribution. These resistive elements are optimized to fit within the available geometry and can reproduce complex flow profiles, such as physiologically relevant flow rates in multi-organ-on-chip platforms. The resulting microfluidic designs are directly exportable for three-dimensional printing. Experimental validation demonstrates that μFG-generated circuits reproduce target flow distributions with 90% accuracy. By streamlining and automating microfluidic circuit creation, μFG not only lowers the barrier to entry for nonexperts but also showcases a principled and efficient application of ML to fluidic system design, enabling rapid and customizable development of complex microfluidic architectures.

Passenger flow distribution forecasting at integrated transport hub via group evolution mechanism and multimodal data

Integrated optimization of spatiotemporal resources at the intersection (IOSTRI) is crucial for traffic signal control, where both the lane allocation and signal control plans are optimized in a unified framework. This paper addresses the IOSTRI problem with delay minimization, formulating it as a binary mixed-integer nonlinear program (BMINLP) model that fully incorporates all possible uses of shared lanes and lane utilization adjustments. A genetic algorithm tailored to the model’s characteristics is designed, where four modules named lane converter, signal plan converter, flow calculation function and delay calculation function are used to calculate the fitness of each solution. Numerical results show the proposed model and algorithm’s ability to adapt to diverse traffic flow distribution patterns. High-quality solutions are obtained within 40–55 seconds, representing a significant improvement over previous studies and satisfying the requirements for real-time adaptive control of a single intersection.

ABSTRACT Understanding the genesis of hydrothermal systems necessitates a clear elucidation of both the deep geothermal field and hydrothermal activity. This study examines the formation mechanisms of the hydrothermal system in the Chuxiong Basin, located adjacent to the South Tibet‐West Yunnan, the largest high‐temperature geothermal belt in China. Through an integrated approach combining hydrochemical analyses and geothermal field characterisation, we clarify the hydrological processes that govern deep water–rock interactions and their influence on hydrochemical evolution, thereby uncovering the mechanisms responsible for geothermal formation. The results demonstrate that the hot springs, which are predominantly recharged by precipitation, are characterised by HCO 3 –Na hydrochemical facies. Despite the high regional heat flow (averaging 72.1 mW/m 2 ), Cenozoic and Cretaceous strata within the basin are shallowly buried and exhibit comparatively low temperatures. In contrast, Jurassic and Triassic strata reach considerably higher temperatures owing to their greater burial depth, particularly beneath the central part of the basin where Jurassic deposits exceed 3000 m in thickness. Deep‐seated faults play a critical role in controlling the spatial distribution of heat flow and act as conduits for the ascent of deep hydrothermal fluids. These findings reveal the establishment of a deep groundwater convective circulation system regulated by major fault structures, providing valuable insights for the development of high‐temperature geothermal resources.

Spatiotemporal distribution of mass flows of quaternary ammonium compounds in Japanese rivers.

The purpose of the present study is to evaluate the geometric impact on the thermal performance of solar thermosiphon tubes through the use of parametric modeling and CFD simulation. To achieve this purpose, three configurations were designed: cylindrical, oval, and with longitudinal fins, and the constant internal volume was maintained to ensure comparable conditions. The models in this paper were developed in the Autodesk Inventor software and then integrated into Autodesk CFD in conditions of average solar irradiance (850 W/m²) and laminar internal flow. The key variables of these results, such as maximum temperature, total heat flow, pressure drop, and internal thermal distribution, were analyzed. The outcomes of the performed analysis show that the finned model is the one with the highest thermal efficiency due to the increased exchange surface area, while the oval design presents an offer with a more homogeneous distribution that does not affect hydraulic behavior significantly. In addition, the cylindrical configuration, although less thermally efficient, permits maintaining a more stable flow profile, and this feature is relevant in passive, pump-less applications. This work presents a technical alternative for residential buildings that has the characteristic of being a low-cost and replicable one, and this viable option combines structural design, thermal analysis, and architectural functionality in areas with a high rate of solar radiation.

Abstract This paper investigates the transient flow behavior and distribution patterns of lubricating oil within high-speed bearings through in-situ visualization. An experimental setup, comprising a transparent bearing and a visualization platform, was developed. Experiments were conducted under varied rotational speeds using two lubricants with different viscosities. A corresponding numerical model was established to simulate the lubrication flow field. The research results indicate that the two lubricants exhibit distinct transient flow characteristics inside the bearing. At lower speeds, spherical oil droplets form on the cage surface, which then deform, elongate, and are ejected. As speed increases, the oil transition to finer filaments or accumulate on the outer ring, depending on the oil viscosity. The Oil Volume Fraction (OVF) on the inner ring, cage, and balls decreases with increasing rotational speed. In contrast, the variation of OVF on the outer ring follows different patterns under ambient and high-temperature conditions, as well as with different lubricants. Overall, the effective oil volume retained inside the bearing cavity is relatively limited, ranging from approximately 0.5 mL to 7.8 mL. The findings of this study provide theoretical guidance for the design of oil-jet lubrication systems in high-speed bearings.

Achieving adequate thermal comfort in classrooms in hot cities in southern Mexico is challenging. A heterogeneous distribution of air conditioning flow leads to thermal discomfort, affecting occupants’ academic performance and increasing energy consumption. This study evaluates the thermal comfort of occupants in an air conditioned classroom using computational fluid dynamics. We determined the effects of variations in air conditioning operating parameters (supply angle, velocity, and temperature) on PMV and modified PMV indices. An operating configuration of 60°, 3 m/s, and 22 °C ensures that thermal comfort remains within regulations while optimizing energy consumption, in contrast to the original PMV model. Using the modified PMV model, the values are 0.38 for students and 0.31 for the teacher, with percentages of dissatisfied individuals of 10% and 7.7%, respectively. This study demonstrates the importance of analyzing air conditioning operating parameters to enhance thermal comfort while reducing energy consumption.

ABSTRACT Solid oxide fuel cells (SOFCs) are a promising next-generation energy technology, yet flow maldistribution remains a key obstacle to their efficient and stable operation. To address the cathode flow field inhomogeneity, this study systematically investigates four manifold configurations (Cases 1–4) using numerical simulations to evaluate their effects on flow distribution and cell performance. The results demonstrate that conventional manifold designs (Cases 1) exhibit significant vortex formation and flow separation at sub-channel inlets due to gas inertial effects, leading to non-uniform flow and oxygen distribution. In contrast, the introduction of square-column flow disruptors (Case 2) and trapezoidal connecting tubes (Case 3) significantly improves flow uniformity, reducing the flow distribution non-uniformity coefficient to 28.07% and 20.03%, respectively. The composite structure (Case 4), which combines the advantages of both optimized designs, not only further reduces the flow non-uniformity coefficient to 19.16% but also decreases the system pressure drop by 12.59%. Notably, the composite manifold (Case 4) demonstrates superior performance in multiple aspects: enhanced electrochemical performance (average current density increased to 0.89159 A/cm2), improved temperature uniformity (maximum temperature difference in the electrolyte layer reduced by 18.04%), and reduced thermal stress (maximum thermal stress decreased by 8.63%). The performance advantage of Case 4 remains robust under both channel scaling (from 13 to 17 channels) and varying inlet flow rates (800–1100 SCCM), confirming its strong adaptability and reliability across different operating and structural conditions. This study provides innovative design strategies for SOFC manifolds, offering significant potential for improving cell efficiency, lifespan, and operational safety.

The TRITON11® fuel design is the latest advancement in boiling water reactor (BWR) fuel technology from Westinghouse, developed to improve fuel cycle economics, thermal performance, and reliability compared to previous designs. This paper provides a comprehensive overview of the thermal-hydraulic testing and modeling efforts supporting the qualification and licensing of the TRITON11 fuel, along with recent innovations related to BWR core thermal-hydraulics. Extensive experimental activities were conducted at the Westinghouse fuel thermal-hydraulic laboratory using the FRODE and FRIGG loops, which simulate prototypical BWR operating conditions. Key tests included critical boiling transition, pressure drop, void fraction, and hydraulic axial force measurements. Additionally, recent tests supporting the development of the new StrongHold ® debris filter are discussed. In parallel, Westinghouse advanced core simulation and subchannel analysis tools (POLCA7/POLCA8 and MEFISTO-T) were further developed, allowing accurate predictions of complex core flow distribution, critical power performance, bundle lift force, and moderator density. The MEFISTO-T code integrates advanced two-phase flow models, in addition to a novel four-field model of annular two-phase flow, explicitly accounting for disturbance waves, along with a multifield transport model of reactor coolant impurities. These models have been validated against experimental data, demonstrating reliable predictive capabilities for critical power and newly observed localized impurity deposition under BWR core conditions. The combined results from these thermal-hydraulic testing and modeling efforts contribute to improved operational flexibility and reliability of Westinghouse BWR fuel designs and support the accurate evaluation of safety margins.

To address the challenges of high computational cost and lengthy design cycles in the high-precision optimization of ray-like underwater gliders, this study proposes a high-accuracy, low-cost parametric modeling and optimization method. The proposed framework begins by extracting the characteristic contours of the manta ray and reconstructing the airfoil sections using the Class-Shape Transformation (CST) method, resulting in a flexible parametric geometry capable of smooth deformation. High-fidelity Computational Fluid Dynamics (CFD) simulations are employed to evaluate the hydrodynamic characteristics, and detailed flow field analyses are conducted to identify the most influential geometric features affecting lift and drag performance. On this basis, a Kriging-based sequential optimization framework is developed. The surrogate model is adaptively refined through dynamic infilling of sample points based on combined Mean Squared Prediction (MSP) and Expected Improvement (EI) criteria, thus improving optimization efficiency while maintaining predictive accuracy. Comparative case studies demonstrate that the proposed method achieves a 116% improvement in lift-to-drag ratio and a more uniform flow distribution, confirming its effectiveness in enhancing both design accuracy and computational efficiency. The results indicate that this approach provides a practical and efficient tool for the parametric design and hydrodynamic optimization of bio-inspired underwater vehicles.

The escalating heat flux density and temperature in highly integrated microelectronic devices adversely affect their reliability and service life, making efficient thermal management crucial for stable operation. This study utilizes Galinstan liquid metal as the coolant to investigate the flow and heat transfer performance in microchannel heat sinks incorporating various turbulator configurations. It is revealed that for microchannels featuring expanded regions, turbulators that create highly symmetric flow fields are preferable due to improved flow distribution. The long teardrop-shaped turbulator provides the best heat transfer performance among all the investigated heat transfer enhancement structures. And this turbulator yields a 13.8-25.9% higher enhancement effectiveness compared to other configurations, at the expense of a 28-41% increase in pressure loss. However, the sudden cross-sectional expansion in the expanded region causes a significant reduction in fluid velocity. Consequently, microchannels with expanded regions and turbulators exhibit a higher bottom surface temperature than the original, straight microchannels, leading to an overall deterioration in heat transfer performance.

In the article, the hydrodynamic processes of the gas distribution elements in the experimental installation of the newly created bubble extractor were investigated, and the distribution of gas flow depending on the size of the gas supply opening to the inner and outer mixing zones of the experimental installation in liquid and gas flow regimes was determined. For the operation of the internal and external mixing zones of the device in a hydrodynamic process of equal intensity, these distributed gas flow rates are of great importance. As a result of the conducted experimental studies, it became possible to correctly select the dimensions of the hole when designing the industrial version of the device.