International Journal of Thermal Sciences最新文献

{"title":"Thermal influence of inter-chip components in two-phase immersion cooling: An experimental and machine learning study","authors":"V.B. Krishnadasan,&nbsp;Pratheek Suresh,&nbsp;C. Balaji","doi":"10.1016/j.ijthermalsci.2025.110560","DOIUrl":"10.1016/j.ijthermalsci.2025.110560","url":null,"abstract":"<div><div>The study investigates the heat transfer characteristics and bubble behavior of a multi-chip system cooled by two-phase immersion cooling technique, with particular focus on the role of inter-chip components on the overall performance. Experiments were conducted for five blockage ratios (B = 0, 0.25, 0.5, 0.75, and 1), representing varying levels of obstruction to vapor flow between the chips. Two operational modes were examined: (i) activation of two vertically adjacent chips and (ii) activation of all seven chips. High-speed imaging was employed to analyze bubble behavior at critical locations- during departure from the lower chip, the inter-chip component and the upper chip. Additionally, an artificial neural network-genetic algorithm (ANN-GA) framework was developed to identify the optimal heat flux distributions corresponding to a predefined chip temperature limit. Results indicate that the presence and geometry of inter-chip components significantly influence thermal uniformity and bubble behavior. The optimum performance was obtained at B = 0.25, which improved the temperature uniformity coefficient and reduced the maximum chip-to-chip temperature difference by nearly 50% compared to the configuration without inter-chip components. Bubble imaging revealed that this configuration promotes coalescence-induced bubble departure, enhancing evaporative heat transfer at the upper chip. For the seven-chip configuration, the influence of blockage ratio was less pronounced but still yielded approximately 15% improvement in temperature uniformity at B = 0.25. The ANN-GA framework demonstrated a strong predictive capability (correlation coefficient 0.96) and suggested that adopting the optimal blockage ratio could increase the total allowable heat load by roughly 20% for a fixed chip temperature limit. These findings provide insights into the coupled effects of inter-chip geometry, bubble dynamics and thermal performance, offering design guidance for thermally efficient multi-chip layouts in two-phase immersion-cooled systems.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"223 ","pages":"Article 110560"},"PeriodicalIF":5.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145754014","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}

{"title":"A comparative investigation of thermo-hydraulic performance in a solar air heater roughened with quarter petal shaped ribs","authors":"Kadhim Al-Chlaihawi ,&nbsp;Khaled Al-Farhany ,&nbsp;Ammar Abdulkadhim","doi":"10.1016/j.ijthermalsci.2025.110580","DOIUrl":"10.1016/j.ijthermalsci.2025.110580","url":null,"abstract":"<div><div>Through a numerical study, the thermo-hydraulic behavior of a solar air heater with quarter petal shaped ribs on its absorber plate is examined including a comparative evaluation of three unique rib configurations. The continuity, momentum (Reynolds-Averaged Navier-Stokes) and energy equations of steady, incompressible, turbulent flow are solved. Renormalization Group (RNG) k -ε turbulence model was chosen to solve the turbulent flow phenomena. The thermal performance has been studied under varying design parameters: relative roughness pitch (7.14 ≤ P/e ≤ 17.86), Reynolds number (4000 ≤ Re ≤ 20,000), while the relative roughness height was kept constant at e/D_h = 0.042. The key performance indicators of the SAH performance are measured against the Nusselt number (Nu), the friction factor (<em>f</em>), the thermal-hydraulic performance factor (TPF) and observation of critical flow features. Results indicated that the configuration of the quarter petal shaped ribs has a decisive impact on the heat transfer and the friction factor features, and its performance becomes very sensitive to the variation in P/e and Re. With the artificially rough SAH, the optimal configuration achieved a TPF of 2.155, which corresponded to a 115.5 % thermal performance enhancement. Correlations for Nu and f as functions of the Reynolds number and relative roughness pitch were obtained by non-linear regression analysis.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"223 ","pages":"Article 110580"},"PeriodicalIF":5.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145754015","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}

{"title":"Effects of flow slip and temperature jump on heat transfer in a ribbed microfluidic channel using lattice Boltzmann method","authors":"Chun-Sheng Wang ,&nbsp;Yu-Wei Chen ,&nbsp;Tong-Miin Liou","doi":"10.1016/j.ijthermalsci.2025.110617","DOIUrl":"10.1016/j.ijthermalsci.2025.110617","url":null,"abstract":"<div><div>As the dimension of electronic devices approaches micrometers, the slip velocities and temperature jumps may play a pivotal role in their thermofluidic performance. Some studies report that the thermal performance increases with Knudsen number (<em>Kn</em>) while others show the opposite observations. The rationale for the discrepancy has not been clarified. In this study, a thermal lattice Boltzmann method is developed to study the effects of flow slips and temperature jumps on heat transfer in a ribbed microfluidic channel filled with air. Varied parameters are respectively the rib height (<span><math><mrow><msubsup><mi>H</mi><mi>r</mi><mo>∗</mo></msubsup></mrow></math></span>), pitch ratio (PR), <em>Kn</em>, and Reynolds number (Re). It is observed for the first time that there exists a critical <span><math><mrow><msubsup><mi>H</mi><mi>r</mi><mo>∗</mo></msubsup></mrow></math></span> = 0.35 beyond which <span><math><mrow><mover><mrow><mi>N</mi><mi>u</mi></mrow><mo>‾</mo></mover><mo>/</mo><msub><mrow><mi>N</mi><mi>u</mi></mrow><mn>0</mn></msub></mrow></math></span> decreases with increasing PR below which <span><math><mrow><mover><mrow><mi>N</mi><mi>u</mi></mrow><mo>‾</mo></mover><mo>/</mo><msub><mrow><mi>N</mi><mi>u</mi></mrow><mn>0</mn></msub></mrow></math></span> rises with increasing PR because of the combined effect of interfacial thermal resistance caused by temperature jumps on the wall and disturbed thermal boundary due to the ribs. For a fixed rib height (<span><math><mrow><msup><msub><mi>H</mi><mi>r</mi></msub><mo>∗</mo></msup></mrow></math></span> = 0.25), the heat transfer enhancement (<span><math><mrow><mover><mrow><mi>N</mi><mi>u</mi></mrow><mo>‾</mo></mover><mo>/</mo><msub><mrow><mi>N</mi><mi>u</mi></mrow><mi>o</mi></msub></mrow></math></span>) is observed to increase with increasing PR and Re and decrease with increasing <em>Kn</em>. In contrast, the pressure loss (<span><math><mrow><mover><mi>f</mi><mo>‾</mo></mover><mo>/</mo><msub><mi>f</mi><mi>o</mi></msub></mrow></math></span>) is found to decrease with increasing PR and <em>Kn</em> and increase with increasing Re. In addition, for the convenience of engineering application, the empirical correlations of <span><math><mrow><mover><mrow><mi>N</mi><mi>u</mi></mrow><mo>‾</mo></mover><mo>/</mo><msub><mrow><mi>N</mi><mi>u</mi></mrow><mi>o</mi></msub></mrow></math></span> and <span><math><mrow><mover><mi>f</mi><mo>‾</mo></mover><mo>/</mo><msub><mi>f</mi><mi>o</mi></msub></mrow></math></span> versus PR, <em>Kn</em> and Re are proposed.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"223 ","pages":"Article 110617"},"PeriodicalIF":5.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145838121","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}

{"title":"A numerical study on an innovative multi-branched inner tube design for double-pipe heat exchangers in high-efficiency renewable energy application","authors":"Joffin Jose Ponnore ,&nbsp;Hazim Moria","doi":"10.1016/j.ijthermalsci.2025.110647","DOIUrl":"10.1016/j.ijthermalsci.2025.110647","url":null,"abstract":"<div><div>Double-pipe heat exchangers have wide applications in renewable energy systems such as solar thermal collectors, geothermal heat loops, and biomass-based energy recovery units. This work presents a novel and pioneering double-pipe heat exchanger featuring an innovative branched inner tube design (see the graphical abstract), which represents a significant departure from conventional configurations and introduces a new paradigm in passive heat transfer enhancement. This unique design simultaneously increases the effective heat transfer surface area and enhances fluid turbulence and mixing, thereby significantly improving thermal performance. To thoroughly assess this design's impact, comprehensive numerical simulations were conducted using a validated finite volume method under turbulent flow conditions. These simulations investigated the dynamic interaction between flow velocities in both the inner and outer tubes, comparing scenarios where the inner tube flow velocity was either higher or lower. Results consistently demonstrate that the multi-branched configuration achieves greater temperature differences and superior overall effectiveness when contrasted with conventional straight-tube designs, particularly in counter-flow arrangements. For instance, the multi-branched setup led to an increase in outlet temperature of up to 7.8 °C in counter-flow at an inner inlet velocity of 0.16 m/s, corresponding to a thermal performance enhancement of approximately 40 % compared to the baseline straight-tube design. While increasing inner tube velocity generally improved the Nusselt number, it also resulted in a more pronounced pressure drop within the multi-branched design. Nevertheless, the multi-branched heat exchanger consistently exhibited substantially higher effectiveness across all velocities and flow patterns. For instance, at 0.16 m/s, the multi-branched design achieved effectiveness values of 0.20 (parallel) and 0.277 (counter), marking improvements of 43 % and 42 % over the straight design's 0.14 and 0.195, respectively. These findings conclusively demonstrate that the proposed multi-branched architecture offers a highly effective, compact, and passive solution for boosting thermal efficiency in renewable energy systems, addressing a critical need for high-performance heat exchangers in space-constrained sustainable applications.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"223 ","pages":"Article 110647"},"PeriodicalIF":5.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145881180","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}

{"title":"Thermal-hydraulic performance and heat transfer modelling of partially filled periodic octet foam heat sinks","authors":"Nitin Hanuman Roge,&nbsp;Shankar Krishnan,&nbsp;S.V. Prabhu","doi":"10.1016/j.ijthermalsci.2025.110632","DOIUrl":"10.1016/j.ijthermalsci.2025.110632","url":null,"abstract":"<div><div>The present study investigates the thermal and hydrodynamic performance of a heat sink channel partially filled with open-cell AlSi10Mg metal foam. Three configurations are considered <span><math><mrow><mo>:</mo><msub><mi>H</mi><mi>f</mi></msub><mo>=</mo><mn>0.5</mn><mi>H</mi></mrow></math></span>, <span><math><mrow><msub><mi>H</mi><mi>f</mi></msub><mo>=</mo><mn>0.75</mn><mi>H</mi></mrow></math></span> and <span><math><mrow><msub><mrow><mspace></mspace><mi>H</mi></mrow><mi>f</mi></msub><mo>=</mo><mi>H</mi></mrow></math></span>, where <span><math><mrow><msub><mi>H</mi><mi>f</mi></msub></mrow></math></span> is the foam height and <span><math><mrow><mi>H</mi></mrow></math></span> is the height of the channel, and they are referred to as Cases 1, 2 and 3, respectively. The study examined over a Reynolds number range of 5000–25,000. The metal foam has a thickness of 12.5 mm and a porosity of 0.706. Wall temperature distributions are captured using a thin stainless steel foil coated with high-emissivity paint and measured through infrared thermography. Results show that reducing the foam height significantly decreases pressure drop, with the <span><math><mrow><mn>0.5</mn><mi>H</mi></mrow></math></span> configuration exhibiting a 10–12 times lower pressure drop than the fully filled case. However, there is a corresponding reduction in heat transfer. Thermal performance evaluation indicates that each configuration achieves a favourable <span><math><mrow><mi>P</mi><mi>E</mi><mi>C</mi></mrow></math></span> and <span><math><mrow><mi>C</mi><mi>P</mi><mi>P</mi><mi>C</mi></mrow></math></span> values. To isolate the heat transfer mechanisms, complementary resin foam experiments demonstrate that nearly 80 % of the total heat transfer is contributed by the metal foam. A unified two-model analysis framework is introduced to quantify mass flow separation, heat transfer, and pressure drop in partially filled channels using structured foams: a behaviour not previously characterised in the literature. Using combined experimental measurements and analytical modelling, the study develops predictive relations capable of accurately estimating both thermal and hydrodynamic performance across porous bypass configurations. A generalised correlation is further proposed to estimate the Nusselt number for both gap and no-gap configurations, formulated using the Reynolds number based on the strut diameter and effective thermal properties. Together, these contributions provide the comprehensive predictive tools tailored specifically for structured lattice foam channels, enabling more reliable design and optimisation under practical heat-transfer and pressure-drop constraints.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"223 ","pages":"Article 110632"},"PeriodicalIF":5.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145881217","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}

{"title":"Heat and mass transfer investigation concerning drug droplet phase change in nasal drug delivery","authors":"Kartika Chandra Tripathy,&nbsp;Ajay Bhandari","doi":"10.1016/j.ijthermalsci.2025.110589","DOIUrl":"10.1016/j.ijthermalsci.2025.110589","url":null,"abstract":"<div><div>The nasal cavity is the primary site for airborne pollutant deposition, making it susceptible to allergic rhinitis, especially in patients with septal deviations. While previous studies have examined drug delivery to standard regions of the nasal passages, limited attention has been given to the pollutant-prone areas in the deviated cavities. Additionally, most models treat drug droplets as inert, smooth spheres, neglecting their size changes due to heat and mass exchange within the thermally conditioned nasal environment. This study addresses these gaps by numerically investigating the deposition behavior of airborne particles and drug droplets in a nasal cavity with an S-shaped septal deviation. Airborne particles are modeled as solids using a Lagrangian approach, while drug droplets are simulated with heat and mass transfer to account for size evolution influenced by the vascularized mucosal lining. A coupled discrete phase–Eulerian wall film model captures film patterns, rebound, coalescence, evaporation, and secondary atomization at the wall surface. Results show significant evaporation for droplets <span><math><mrow><mo>≤</mo></mrow></math></span> 5 μm, with complete evaporation at 2 μm. The droplets (10 and 15 μm) demonstrate even deposition patterns and improved surface coverage. Droplet evaporation is reduced under humid, cool conditions but becomes significant in dry, warm environments. Optimal spray parameters vary by droplet size: 10 μm (10°, 5 m/s), 15 μm (30°, 15 m/s), 20 μm (20°, 5 m/s), and 25 μm (20°, 10 m/s). This study offers a novel and comprehensive simulation framework to inform nasal drug delivery design in anatomically deviated airways, improving therapeutic strategies for allergic rhinitis.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"223 ","pages":"Article 110589"},"PeriodicalIF":5.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145789443","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}

{"title":"Influence of deposition strategy on melt pool behavior and forming morphology of directed energy deposition-arc","authors":"Qianru Wu ,&nbsp;Maoqi Xu ,&nbsp;Chengchun Zhang ,&nbsp;Kuilin Huang ,&nbsp;Jiachen Wang ,&nbsp;Jiquan Yang ,&nbsp;Changmeng Liu","doi":"10.1016/j.ijthermalsci.2025.110600","DOIUrl":"10.1016/j.ijthermalsci.2025.110600","url":null,"abstract":"<div><div>In directed energy deposition-arc (DED-arc), the melt pool's thermodynamic behavior significantly impacts component morphology. Most existing studies focus on the influence of individual process parameters, with limited systematic investigation into the effects of key deposition strategies such as scanning strategy, interlayer cooling time, and deposition length. To address this, this study establishes a three-dimensional transient numerical model of DED-arc to systematically investigate how these strategies influence the melt pool's dynamics and formation characteristics. The results show that, increasing the interlayer cooling time from 0 s to 10 s significantly improves dimensional uniformity by approximately 19.7 %, achieved by decreasing the average deposition width by about 6.1 % and increasing the height by nearly 25.9 %. Furthermore, compared with unidirectional scanning, a bidirectional scanning strategy optimizes heat accumulation and enhances melt pool stability. Increasing the deposition length extends the stable formation zone, effectively mitigating the adverse impact of end instabilities on overall morphology. This study provides quantitative theoretical guidance for process optimization, parameter selection, and stable multi-layer formation in DED-arc.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"223 ","pages":"Article 110600"},"PeriodicalIF":5.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145789450","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}

{"title":"Centrifugal-buoyancy instability on transient fluid flow and energy distribution through a strongly bent rectangular channel","authors":"Selim Hussen ,&nbsp;Ratan Kumar Chanda ,&nbsp;Sanjit Kumar Paul ,&nbsp;Rabindra Nath Mondal","doi":"10.1016/j.ijthermalsci.2025.110611","DOIUrl":"10.1016/j.ijthermalsci.2025.110611","url":null,"abstract":"<div><div>This study numerically investigates the buoyancy effect and centrifugal influence on the onset of secondary vortex generation in non-isothermal flow through a strongly bent rectangular channel with an aspect ratio of 2. The channel is such that the bottom wall is heated while cooling from the top; the vertical sidewalls are adiabatic. Using a spectral approach for the dimensionless parameters, the buoyancy force (the Grashof number, <span><math><mrow><mrow><mspace></mspace><mi>G</mi><mi>r</mi><mo>=</mo><mn>1000</mn></mrow><mo>)</mo></mrow></math></span>, centrifugal force <span><math><mrow><mo>(</mo><mrow><mtext>curvature</mtext><mo>,</mo><mi>δ</mi><mo>=</mo><mn>0.5</mn></mrow><mo>)</mo></mrow></math></span>, Prandtl number (<span><math><mrow><mrow><mi>Pr</mi><mo>=</mo><mn>7.0</mn><mspace></mspace><mtext>for</mtext><mspace></mspace><mtext>water</mtext></mrow><mo>)</mo></mrow></math></span> and an assortment of pressure gradient parameters, the Dean number <span><math><mrow><mo>(</mo><mrow><mn>0</mn><mo>&lt;</mo><mi>D</mi><mi>n</mi><mo>≤</mo><mn>1500</mn></mrow><mo>)</mo></mrow></math></span>, a linearly unstable steady branch comprising a symmetric 2-vortex solution is obtained. The non-linear features of the transient flow are examined by considering the time advancement analysis of the resistance coefficient (<span><math><mrow><mi>λ</mi></mrow></math></span>) and the Nusselt number (<span><math><mrow><mrow><mi>N</mi><mi>u</mi></mrow><mo>)</mo></mrow></math></span>. The analysis reveals an asymmetric solution of unsteady flow caused by the strong centrifugal force. A 2- to 4-vortex of multi-periodic state and a 2- to 6-vortex of chaotic flow phenomena are observed, where the solution structure is affirmed with the phase space and the power spectrum analysis. The study also compares the results with the slight curvature <span><math><mrow><mo>(</mo><mi>δ</mi><mo>=</mo><mn>0.001</mn></mrow></math></span>) flow with comparatively low buoyancy force (<span><math><mrow><mi>G</mi><mi>r</mi><mo>=</mo><mn>500</mn></mrow></math></span>) on the vortex structure. Finally, energy distribution from the heated wall to the fluid is investigated through <span><math><mrow><mi>N</mi><mi>u</mi></mrow></math></span> and the time average of <span><math><mrow><mi>N</mi><mi>u</mi></mrow></math></span>. The chaotic phenomena are explored to regulate heat transfer due to the strong flow at higher Dean numbers. TECPLOT 360 is used for flow visualization, and CODE BLOCK is utilized for simulation.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"223 ","pages":"Article 110611"},"PeriodicalIF":5.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145838086","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}

{"title":"Programmable metasurfaces far-field scattering amplitude modulation based on FPGA expansion modules","authors":"Bin Lou ,&nbsp;Bowen Zeng ,&nbsp;Xufeng Jing","doi":"10.1016/j.ijthermalsci.2025.110612","DOIUrl":"10.1016/j.ijthermalsci.2025.110612","url":null,"abstract":"<div><div>—Compared to conventional metasurfaces, digitally encoded metasurfaces provide a simpler and more convenient method of physical modulation, demonstrating electromagnetic control of metasurfaces in a concise manner. We propose a programmable metasurfaces consisting of external circuits with amplitude modulation for enhanced control of electromagnetic beams. An FPGA (Field Programmable Gate Array) is utilized to control the PIN diode on each metasurfaces cell, and the phase state of the metasurfaces cell is controlled by changing the bias voltage. Importantly, we introduced a \"sampling resistor\" method to change the amplitude of individual superlattices without changing the phase of the superlattice. By applying this method to beam splitting control, the scattered energy of each beam can be independently regulated without changing the beam direction.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"223 ","pages":"Article 110612"},"PeriodicalIF":5.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145838126","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}

{"title":"Modeling of stress field and process parameter optimization in laser welding of thin-walled components based on microstructural analysis","authors":"Liuyang Li ,&nbsp;Yanbin Zhang ,&nbsp;Kaiyao Li ,&nbsp;Qingfeng Bie ,&nbsp;Xuelei Song ,&nbsp;Guanqun Li ,&nbsp;Fuyou Wang ,&nbsp;Peng Gong ,&nbsp;Lingyi Sun ,&nbsp;Changhe Li","doi":"10.1016/j.ijthermalsci.2025.110619","DOIUrl":"10.1016/j.ijthermalsci.2025.110619","url":null,"abstract":"<div><div>Laser welding is widely used for joining thin-walled SUS304 stainless-steel components in applications such as commercial kitchenware, aerospace, and automotive structures, where dimensional accuracy and deformation control are critical. However, the high energy density and localized heating of laser beams easily induce large temperature gradients, leading to significant welding deformation and residual stress in thin plates. For 1.0 mm-thick SUS304 stainless-steel specimens. A three-dimensional finite-difference temperature-field model and an accompanying stress-field model for thin-walled welding were developed. These models assume a double-ellipsoidal heat source, isotropic thermal conductivity, and initial room temperature. The double-ellipsoidal heat-source model was calibrated, and stress deformation was experimentally verified. For 1.0 mm-thick SUS304 stainless-steel specimens, the temperature-field model showed a maximum error of 1.5 %, while the stress-deformation model exhibited trends consistent with experimental results. Additionally, the combined effects of welding power and speed on welding temperature, thermal deformation, and both macroscopic and microscopic weld morphology were investigated for the 1.0 mm-thick SUS304 stainless-steel specimens. Optimal welding parameters were determined through a comprehensive analysis of the welding temperature, molten pool features, and EBSD analysis. With a laser power of 600 W and welding speed of 4 m/min, a lower welding temperature (1450 °C), reduced microstrain (3500), and a stable molten-pool state has been achieved. This study provides theoretical insights into the welding principles of thin-walled components and lays the groundwork for optimizing process parameters.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"223 ","pages":"Article 110619"},"PeriodicalIF":5.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145838137","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}