Artykuły w czasopismach: „Cooling dynamics”

1

Horiuchi, Noriaki. "Cooling dynamics". Nature Photonics 10, nr 12 (29.11.2016): 751. http://dx.doi.org/10.1038/nphoton.2016.246.

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BALMFORTH, N. J., R. V. CRASTER i R. SASSI. "Dynamics of cooling viscoplastic domes". Journal of Fluid Mechanics 499 (25.01.2004): 149–82. http://dx.doi.org/10.1017/s0022112003006840.

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HOANG, VO VAN, i SUHK KUN OH. "COOLING RATE EFFECTS ON DYNAMICS IN SUPERCOOLED Al2O3". International Journal of Modern Physics B 20, nr 08 (30.03.2006): 947–67. http://dx.doi.org/10.1142/s0217979206033589.

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The cooling rate effects in supercooled Al 2 O 3 have been investigated by Molecular Dynamics (MD) method. Simulations were done in the basic cube under periodic boundary conditions containing 3000 ions with Born–Mayer type pair potentials. The temperature of the system was decreased linearly in time as T(t)=T0–γt, where γ is the cooling rate. The cooling rate dependence of density, thermal expansion coefficient and enthalpy of the system was found. Structure of amorphous Al 2 O 3 model at the temperature of 0 K was in good agreement with Lamparter's experimental data. The cooling rate dependence of the dynamical heterogeneities in supercooled states has been studied through the comparison of the partial radial distribution functions (PRDFs) for the 10% most mobile or immobile particles with the corresponding mean PRDFs in the models. Also, cooling rate effects on the cluster size distributions of the most mobile or immobile particles have been obtained. Calculations show that the cooling rate effects on the dynamical heterogeneities are pronounced. Finally, the evolution of structural defects and cluster size distributions of the most mobile or immobile particles in the system upon cooling has been studied and presented.

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4

Park, Chanwoo, Jaewoo Seol, Ali Aldalbahi, Mostafizur Rahaman, Alexander L. Yarin i Sam S. Yoon. "Drop impact phenomena and spray cooling on hot nanotextured surfaces of various architectures and dynamic wettability". Physics of Fluids 35, nr 2 (luty 2023): 027126. http://dx.doi.org/10.1063/5.0139960.

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Spray cooling has been used to quench metal slabs during casting, cool nuclear reactors, suppress accidental fires, and remove heat from high-power density electronics. In particular, the miniaturization of electronic devices inevitably results in an increased power density or heat flux on the microelectronics surfaces and poses a threat of a thermal shutdown of such devices when cooling is insufficient. Surface nanotexturing effectively augments additional liquid-to-substrate surface area, thereby increasing cooling capability, as well as an effective heat transfer coefficient. In spray cooling, surface dynamic wettability also affects drop impact dynamics and subsequent coolant evaporation on a hot surface. Herein, we introduced various nanotextured surfaces and affected dynamic wettability using the so-called thorny-devil nanofibers, nickel nanocones, Teflon and titania nanoparticles, and zinc nanowires. The effect of these different nanoscale architectures on drop impact phenomena and subsequent evaporative cooling was investigated. These nanotextured surfaces were fabricated using various deposition methods, including electrospinning, electroplating, supersonic spraying, aerosol deposition, and chemical bath deposition. We found that the surface with greater dynamic wettability related to the hydrodynamic focusing considerably improved the heat removal capability by furthering the Leidenfrost limit and facilitating drop spreading. In particular, the thorny-devil nanofiber surface yielded the highest heat flux at all ranges of the Reynolds and Weber numbers. Spray cooling on a model electronic kit also confirmed that the thorny-devil nanofibers were most effective in cooling the surface of the model kit during multiple cycles of water spraying.

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Zhang, Junyan, Yunwei Mao, Dong Wang, Ju Li i Yunzhi Wang. "Accelerating ferroic ageing dynamics upon cooling". NPG Asia Materials 8, nr 10 (październik 2016): e319-e319. http://dx.doi.org/10.1038/am.2016.152.

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Vega, Aurelio, Fernando V. Díez i José M. . Alvarez. "Dynamics of a Batch Cooling Crystallizer." JOURNAL OF CHEMICAL ENGINEERING OF JAPAN 29, nr 5 (1996): 817–24. http://dx.doi.org/10.1252/jcej.29.817.

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Hägele, D., R. Zimmermann, M. Oestreich, M. R. Hofmann, W. W. Rühle, B. K. Meyer, H. Amano i I. Akasaki. "Cooling dynamics of excitons in GaN". Physical Review B 59, nr 12 (15.03.1999): R7797—R7800. http://dx.doi.org/10.1103/physrevb.59.r7797.

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Alouani Bibi, Fathallah, James Binney, Katherine Blundell i Henrik Omma. "AGN effect on cooling flow dynamics". Astrophysics and Space Science 311, nr 1-3 (18.07.2007): 317–21. http://dx.doi.org/10.1007/s10509-007-9542-4.

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Lee, S. Y., Y. Zhang i K. Y. Ng. "Damping dynamics of optical stochastic cooling". Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 532, nr 1-2 (październik 2004): 340–44. http://dx.doi.org/10.1016/j.nima.2004.06.063.

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Liu, T. X., W. G. Lynch, M. J. van Goethem, X. D. Liu, R. Shomin, W. P. Tan, M. B. Tsang i in. "Cooling dynamics in multi-fragmentation processes". Europhysics Letters (EPL) 74, nr 5 (czerwiec 2006): 806–12. http://dx.doi.org/10.1209/epl/i2006-10040-x.

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Shiromaru, H., T. Furukawa, G. Ito, N. Kono, H. Tanuma, J. Matsumoto, M. Goto i in. "Cooling dynamics of carbon cluster anions". Journal of Physics: Conference Series 635, nr 1 (7.09.2015): 012035. http://dx.doi.org/10.1088/1742-6596/635/1/012035.

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Friedrichs, S., H. P. Hodson i W. N. Dawes. "The Design of an Improved Endwall Film-Cooling Configuration". Journal of Turbomachinery 121, nr 4 (1.10.1999): 772–80. http://dx.doi.org/10.1115/1.2836731.

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The endwall film-cooling cooling configuration investigated by Friedrichs et al. (1996, 1997) had in principle sufficient cooling flow for the endwall, but in practice, the redistribution of this coolant by secondary flows left large endwall areas uncooled. This paper describes the attempt to improve upon this datum cooling configuration by redistributing the available coolant to provide a better coolant coverage on the endwall surface, while keeping the associated aerodynamic losses small. The design of the new, improved cooling configuration was based on the understanding of endwall film-cooling described by Friedrichs et al. (1996, 1997). Computational fluid dynamics were used to predict the basic flow and pressure field without coolant ejection. Using this as a basis, the above-described understanding was used to place cooling holes so that they would provide the necessary cooling coverage at minimal aerodynamic penalty. The simple analytical modeling developed by Friedrichs et al. (1997) was then used to check that the coolant consumption and the increase in aerodynamic loss lay within the limits of the design goal. The improved cooling configuration was tested experimentally in a large-scale, low-speed linear cascade. An analysis of the results shows that the redesign of the cooling configuration has been successful in achieving an improved coolant coverage with lower aerodynamic losses, while using the same amount of coolant as in the datum cooling configuration. The improved cooling configuration has reconfirmed conclusions from Friedrichs et al. (1996, 1997): First, coolant ejection downstream of the three-dimensional separation lines on the endwall does not change the secondary flow structures; second, placement of holes in regions of high static pressure helps reduce the aerodynamic penalties of platform coolant ejection; finally, taking account of secondary flow can improve the design of endwall film-cooling configurations.

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Li, Xianchang, i Ting Wang. "Simulation of Film Cooling Enhancement With Mist Injection". Journal of Heat Transfer 128, nr 6 (9.12.2005): 509–19. http://dx.doi.org/10.1115/1.2171695.

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Cooling of gas turbine hot-section components, such as combustor liners, combustor transition pieces, and turbine vanes (nozzles) and blades (buckets), is a critical task for improving the life and reliability of them. Conventional cooling techniques using air-film cooling, impingement jet cooling, and turbulators have significantly contributed to cooling enhancements in the past. However, the increased net benefits that can be continuously harnessed by using these conventional cooling techniques seem to be incremental and are about to approach their limit. Therefore, new cooling techniques are essential for surpassing these current limits. This paper investigates the potential of film-cooling enhancement by injecting mist into the coolant. The computational results show that a small amount of injection (2% of the coolant flow rate) can enhance the adiabatic cooling effectiveness about 30–50%. The cooling enhancement takes place more strongly in the downstream region, where the single-phase film cooling becomes less powerful. Three different holes are used in this study including a two-dimensional (2D) slot, a round hole, and a fan-shaped diffusion hole. A comprehensive study is performed on the effect of flue gas temperature, blowing angle, blowing ratio, mist injection rate, and droplet size on the cooling effectiveness with 2D cases. Analysis on droplet history (trajectory and size) is undertaken to interpret the mechanism of droplet dynamics.

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Jaiswal, Abhishek, i Yang Zhang. "Robustness of Dynamical Cluster Analysis in a Glass-Forming Metallic Liquid using an Unsupervised Machine Learning Algorithm". MRS Advances 1, nr 26 (2016): 1929–34. http://dx.doi.org/10.1557/adv.2016.52.

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ABSTRACTWe performed dynamical cluster analysis in a Cu-Zr-Al based glass-forming metallic liquid using an unsupervised machine learning algorithm. The size of the dynamical clusters is used to quantify the onset of cooperative dynamics as the underlying mechanism leading to the Arrhenius dynamic crossover in transport coefficients of the metallic liquid. This technique is useful to directly visualize dynamical clusters and quantify their sizes upon cooling. We demonstrate the robustness of this algorithm by performing sensitivity analysis against two key parameters: number of mobility groups and inconsistency coefficient of the hierarchical cluster tree. The results elucidate the optimized range of values for both of these parameters that capture the underlying physical picture of increasing cooperative dynamics appropriately.

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15

Kapilan, N., M. Manjunath Gowda i H. N. Manjunath. "Computational Fluid Dynamics Analysis of an Evaporative Cooling System". Strojnícky casopis – Journal of Mechanical Engineering 66, nr 2 (1.11.2016): 117–24. http://dx.doi.org/10.1515/scjme-2016-0026.

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Abstract The use of chlorofluorocarbon based refrigerants in the air-conditioning system increases the global warming and causes the climate change. The climate change is expected to present a number of challenges for the built environment and an evaporative cooling system is one of the simplest and environmentally friendly cooling system. The evaporative cooling system is most widely used in summer and in rural and urban areas of India for human comfort. In evaporative cooling system, the addition of water into air reduces the temperature of the air as the energy needed to evaporate the water is taken from the air. Computational fluid dynamics is a numerical analysis and was used to analyse the evaporative cooling system. The CFD results are matches with the experimental results.

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Larpruenrudee, Puchanee, Doan Khai Do, Nick S. Bennett, Suvash C. Saha, Mohammad Ghalambaz i Mohammad S. Islam. "Computational Fluid Dynamics Analysis of Spray Cooling in Australia". Energies 16, nr 14 (12.07.2023): 5317. http://dx.doi.org/10.3390/en16145317.

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Spray cooling technology offers high levels of uniform heat removal with very low fluid volumes and has found recent application in relatively small-scale use cases. Since it is a complex process, research can enable spray cooling to be applied more widely and at larger scales, such as in HVAC, as a means to operate more efficiently. Weather conditions are one of the main parameters that directly affect the effectiveness of spray cooling. This study investigates the spray cooling performance for temperature and humidity conditions in six Australian cities. ANSYS Fluent (2021 R1) software is applied for the numerical simulation. The numerical model is first validated with the available literature before a numerical simulation is conducted to assess each city throughout the year. These include Adelaide, Brisbane, Darwin, Melbourne, Perth, and Sydney. The spray cooling pattern, temperature, and humidity distribution, as well as the evaporation effect on different regions in Australia, is simulated and analysed based on the CFD technique. The results from this study indicate that weather conditions influence spray cooling for all cities, especially in summer. Along the wind tunnel, the temperature significantly drops at the spray cooling area, while the humidity increases. Due to the effect of spray cooling inside the wind tunnel, the temperature at the outlet is still lower than the inlet for all cases. However, the humidity at the outlet is higher than the inlet for all cases.

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17

Stasiuk, Mark V., Claude Jaupart, R. Stephen i J. Sparks. "Influence of cooling on lava-flow dynamics". Geology 21, nr 4 (1993): 335. http://dx.doi.org/10.1130/0091-7613(1993)021<0335:iocolf>2.3.co;2.

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Hayes, J. R., A. F. J. Levi i W. Weigmann. "Dynamics of injected electron cooling in GaAs". Applied Physics Letters 48, nr 20 (19.05.1986): 1365–67. http://dx.doi.org/10.1063/1.96911.

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Goncharov, V. P., i V. I. Pavlov. "Dynamics of Upward Jets with Newtonian Cooling". Journal of Experimental and Theoretical Physics 126, nr 2 (luty 2018): 276–83. http://dx.doi.org/10.1134/s106377611801003x.

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BALMFORTH, N. J., i R. V. CRASTER. "Dynamics of cooling domes of viscoplastic fluid". Journal of Fluid Mechanics 422 (3.11.2000): 225–48. http://dx.doi.org/10.1017/s002211200000166x.

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A non-isothermal viscoplastic thin-layer theory is developed to explore the effects of surface cooling, yield stress, and shear thinning on the evolution of non-isothermal domes of lava and laboratory fluids. The fluid is modelled using the Herschel–Bulkley constitutive relations, but modified to have temperature-dependent viscosity and yield stress. The thin-layer equations are solved numerically to furnish models of expanding, axisymmetrical domes. Linear stability theory reveals the possibility of non-axisymmetrical, fingering-like instability in these domes. Finally, the relevance to lava and experiments is discussed.

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Raithel, G., G. Birkl, A. Kastberg, W. D. Phillips i S. L. Rolston. "Cooling and Localization Dynamics in Optical Lattices". Physical Review Letters 78, nr 4 (27.01.1997): 630–33. http://dx.doi.org/10.1103/physrevlett.78.630.

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Xie, Yongkun, Guoxiong Wu, Yimin Liu i Jianping Huang. "Eurasian Cooling Linked with Arctic Warming: Insights from PV Dynamics". Journal of Climate 33, nr 7 (1.04.2020): 2627–44. http://dx.doi.org/10.1175/jcli-d-19-0073.1.

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AbstractThe three-dimensional connections between Eurasian cooling and Arctic warming since 1979 were investigated using potential vorticity (PV) dynamics. We found that Eurasian cooling can be regulated by Arctic warming through PV adaptation and PV advection. Here, PV adaptation refers to the adaptation of PV to forcing and coherent dynamic–thermodynamic adaptation to PV change. In a PV perspective, first, the anticyclonic circulation change over the Arctic is produced by a negative PV change through PV adaptation, in which the change means the linear trend from 1979 to 2017. The negative PV change is directly regulated by Arctic warming because the vertical structure of Arctic warming is stronger at lower levels, which generates a negative PV change through the diabatic heating effect. Second, the circulation change produces a change in horizontal PV advection due to the existence of climatological PV gradients. Thus, as a balanced result, both the circulation change and PV change extend to the midlatitudes through horizontal PV advection and PV adaptation. Eventually, Eurasian cooling at the surface and in the lower troposphere is dominated by PV changes at the surface through PV adaptation. Meanwhile, enhanced Eurasian cooling in the middle troposphere is dominated by top-down influences of upper-level PV change through PV adaptation. Nevertheless, the upper-level PV changes are still contributed to by horizontal PV advection associated with Arctic warming. Overall, the general dynamics connecting Eurasian cooling with Arctic warming are demonstrated in a PV view.

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Weaver, Richard, i Sangmin Lee. "Slow dynamics in a single bead with mechanical conditioning and transient heating". Journal of the Acoustical Society of America 153, nr 3_supplement (1.03.2023): A113. http://dx.doi.org/10.1121/10.0018345.

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The ultrasonically-measured contact stiffness of an aluminum bead confined between two slabs diminishes on mechanical conditioning, and then recovers like log(t) after the conditioning ceases. Here that structure is evaluated for its response to transient heating and cooling, with and without accompanying conditioning vibrations. It is found that, under heating or cooling alone, stiffness changes are mostly consistent with temperature dependent material moduli; there is little or no slow dynamics. Hybrid tests in which vibration conditioning is followed by heating or cooling lead to recoveries that begin like log(t) and then become more complex. On subtracting the known response to heating or cooling alone we discern the influence of higher or lower temperatures on slow dynamic recovery from vibrations. It is found that heating accelerates the initial log(t) recovery, but by an amount more than predicted by an Arrhenius model of thermally activated barrier penetrations. Transient cooling has no discernable effect, in contrast to the Arrhenius prediction that it inhibits recovery. [Supported by the DOE, DE-SC0021056].

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Thomas, Mitra, i Thomas Povey. "Improving turbine endwall cooling uniformity by controlling near-wall secondary flows". Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 231, nr 14 (25.10.2016): 2689–705. http://dx.doi.org/10.1177/0954410016673092.

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In this paper, we propose a design philosophy for cooling high-pressure nozzle guide vane endwalls, which exploits the momentum of cooling jets to control vane secondary flows thereby improving endwall cooling uniformity. The impact of coolant-to-mainstream pressure ratio, hole inclination angle, hole diameter, vane potential field, and overall mass flux ratios are considered. Arguments are developed by examining detailed experimental studies conducted in a large-scale low-speed cascade tunnel with engine-realistic combustor geometry and turbulence profiles. Computational fluid dynamics predictions validated by the same are used to extend the parameter space. We show that the global flow field is highly sensitive to the inlet total pressure profile, which in turn can be modified by introducing relatively low mass flow rates of cooling gas at engine realistic coolant-to-mainstream pressure ratios and mass flux ratios. This interaction effect must be understood for successful design of optimised endwall cooling schemes, an effect which is not sufficiently emphasized in much of the literature on this topic. Design guidelines are given that we hope will be of use in industry.

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Ivy, Diane J., Susan Solomon i Harald E. Rieder. "Radiative and Dynamical Influences on Polar Stratospheric Temperature Trends". Journal of Climate 29, nr 13 (21.06.2016): 4927–38. http://dx.doi.org/10.1175/jcli-d-15-0503.1.

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Abstract Radiative and dynamical heating rates control stratospheric temperatures. In this study, radiative temperature trends due to ozone depletion and increasing well-mixed greenhouse gases from 1980 to 2000 in the polar stratosphere are directly evaluated, and the dynamical contributions to temperature trends are estimated as the residual between the observed and radiative trends. The radiative trends are obtained from a seasonally evolving fixed dynamical heating calculation with the Parallel Offline Radiative Transfer model using four different ozone datasets, which provide estimates of observed ozone changes. In the spring and summer seasons, ozone depletion leads to radiative cooling in the lower stratosphere in the Arctic and Antarctic. In Arctic summer there is weak wave driving, and the radiative cooling due to ozone depletion is the dominant driver of observed trends. In late winter and early spring, dynamics dominate the changes in Arctic temperatures. In austral spring and summer in the Antarctic, strong dynamical warming throughout the mid- to lower stratosphere acts to weaken the strong radiative cooling associated with the Antarctic ozone hole and is indicative of a strengthening of the Brewer–Dobson circulation. This dynamical warming is a significant term in the thermal budget over much of the Antarctic summer stratosphere, including in regions where strong radiative cooling due to ozone depletion can still lead to net cooling despite dynamical terms. Quantifying the contributions of changes in radiation and dynamics to stratospheric temperature trends is important for understanding how anthropogenic forcings have affected the historical trends and necessary for projecting the future.

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Lei, Chun Li, Zhi Yuan Rui, Te Li i Qin Wu. "Research on the Cooling System of High-Speed Motorized Spindle". Applied Mechanics and Materials 716-717 (grudzień 2014): 1707–10. http://dx.doi.org/10.4028/www.scientific.net/amm.716-717.1707.

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In order to control effectively the temperature of the motorized spindle, based on thermodynamics, heat transfer theory and fluid dynamics control theory, the model of motorized spindle with cooling system is established and simulated. Based on the idea of orthogonal experiment and simulation experiment, the comprehensive tests are built, and the optimum matching relation between the heat flux of motor and the flow velocity of cooling liquid is determined in this article. The results show that the flow velocity of coolant can be adjusted according to the heat flux of motor which can control the temperature in the steady range and improves the cooling effect.

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MARCONI, UMBERTO MARINI BETTOLO, ANDREA BALDASSARRI i ANDREA PUGLISI. "MODELS OF FREE COOLING GRANULAR GASES". Advances in Complex Systems 04, nr 04 (grudzień 2001): 321–31. http://dx.doi.org/10.1142/s0219525901000292.

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We consider the free evolution of systems of granular particles whose dynamics is characterized by a collision rule which preserves the total momentum, but dissipates the kinetic energy. Starting from an inelastic version of a minimal model proposed by Ulam for a gas of Maxwell molecules, we introduce a new lattice model aimed at investigating the role of dynamical correlations and the onset of spatial order induced by the inelasticity of the interactions. We study, in one- and two-dimensional cases, the velocity distribution, the decay of the energy, the formation of spatial structures and topological defects. Finally, we relate our findings to other models known in other fields.

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Jia, Jun Li, Jin Hong Zhang i Guo Zhen Wang. "Metallurgical Secondary Cooling of Continuous Casting Based on Neural Network Adaptive System Design of Water Distribution". Advanced Materials Research 926-930 (maj 2014): 802–5. http://dx.doi.org/10.4028/www.scientific.net/amr.926-930.802.

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Efficient secondary cooling water control level slab continuous casting process and quality are closely related. Casting solidification heat transfer model is the basis of process control and optimization, heat transfer model based on determining the secondary cooling system is the most widely used method for casting production process can be simulated. However, when considering the many factors affecting the production and input conditions change significantly, real-time and strain of this method is not guaranteed. Therefore, the artificial intelligence optimization algorithms such as genetic algorithms, neural networks, fuzzy controllers, introducing continuous casting secondary cooling water distribution and dynamics of optimal control methods, the rational allocation of caster secondary cooling water and dynamic control is important.

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Burdet, André, i Reza S. Abhari. "Three-Dimensional Flow Prediction and Improvement of Holes Arrangement of a Film-Cooled Turbine Blade Using a Feature-Based Jet Model". Journal of Turbomachinery 129, nr 2 (6.06.2006): 258–68. http://dx.doi.org/10.1115/1.2437778.

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A feature-based jet model has been proposed for use in three-dimensional (3D) computational fluid dynamics (CFD) prediction of turbine blade film cooling. The goal of the model is to be able to perform computationally efficient flow prediction and optimization of film-cooled turbine blades. The model reproduces in the near-hole region the macroflow features of a coolant jet within a Reynolds-averaged Navier-Stokes framework. Numerical predictions of the 3D flow through a linear transonic film-cooled turbine cascade are carried out with the model, with a low computational overhead. Different cooling holes arrangements are computed, and the prediction accuracy is evaluated versus experimental data. It is shown that the present model provides a reasonably good prediction of the adiabatic film-cooling effectiveness and Nusselt number around the blade. A numerical analysis of the interaction of coolant jets issuing from different rows of holes on the blade pressure side is carried out. It is shown that the upward radial migration of the flow due to the passage secondary flow structure has an impact on the spreading of the coolant and the film-cooling effectiveness on the blade surface. Based on this result, a new arrangement of the cooling holes for the present case is proposed that leads to a better spanwise covering of the coolant on the blade pressure side surface.

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Hosseini, Ebrahim. "Effects of Various Injection Holes with/without Opening Angles of Film Cooling on Blades of Gas Turbine: A CFD Approach". Trends in Sciences 18, nr 22 (31.10.2021): 452. http://dx.doi.org/10.48048/tis.2021.452.

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The combustor exit temperature is steadily rising to improve the overall efficiency of the gas turbine. As a result, film cooling, the most important and necessary cooling technology, must be developed further to satisfy this demanding requirement. The film cooling performance on the NACA 0012 gas turbine blade is numerically evaluated in this research using 6 different injection holes with and without opening angles. The Computational Fluid Dynamics (CFD) software Ansys Fluent v16 is used to conduct 2-dimensional Reynolds-Averaged Navier-Stokes (RANS) flow and heat transfer analyses. The flow is assumed to be steady, turbulent, and incompressible. To obtain solutions, the incompressible RANS equations are solved using the finite-volume technique. The simulation results indicate that the SST k-ω turbulence model is appropriate for simulating flow characteristics and evaluating film cooling efficiency over the blade. Furthermore, the opening angle has a beneficial impact on the upper blade surface's cooling performance. The injection hole with an opening angle of 15º and a height of D (injection hole diameter) achieves the maximum value of cooling efficiency. The coolant injected from the hole provides greater cooling coverage for the entire blade in this configuration, increasing cooling effectiveness. HIGHLIGHTS The influence of various geometries of injection holes on the effectiveness of film cooling was investigated The low opening angle has a greater impact on film cooling than the other opening angles The injection hole with an opening angle eliminates the recirculation region after the coolant exits GRAPHICAL ABSTRACT

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Weigler, Max, Martin Brodrecht, Hergen Breitzke, Felix Dietrich, Matthias Sattig, Gerd Buntkowsky i Michael Vogel. "2H NMR Studies on Water Dynamics in Functionalized Mesoporous Silica". Zeitschrift für Physikalische Chemie 232, nr 7-8 (26.07.2018): 1041–58. http://dx.doi.org/10.1515/zpch-2017-1034.

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AbstractMesoporous silica MCM-41 is prepared, for which the inner surfaces are modified by 3-(aminopropyl)triethoxysilane (APTES) in a controlled manner. Nitrogen gas adsorpition yields a pore diameter of 2.2 nm for the APTES functionalized MCM-41.2H nuclear magnetic resonance (NMR) and broadband dielectric spectroscopy (BDS) provide detailed and consistent insights into the temperature-dependent reorientation dynamics of water in this confinement. We find that a liquid water species becomes accompanied by a solid water species when cooling through ~210 K, as indicated by an onset of bimodal2H spin-lattice relaxation. The reorientation of the liquid water species is governed by pronounced dynamical heterogeneity in the whole temperature range. Its temperature dependence shows a mild dynamic crossover when the solid water species emerges and, hence, the volume accessible to the liquid water species further shrinks. Therefore, we attribute this variation in the temperature dependence to a change from bulk-like behavior towards interface-dominated dynamics. Below this dynamic crossover,2H line-shape and stimulted-echo studies show that water reorientation becomes anisotropic upon cooling, suggesting that these NMR approaches, but also BDS measurements do no longer probe the structural (α) relaxation, but rather a secondary (β) relaxation of water at sufficiently low temperatures. Then, another dynamic crossover at ~180 K can be rationalized in terms of a change of the temperature dependence of theβrelaxation in response to a glassy freezing of theαrelaxation of confined water. Comparing these results for APTES modied MCM-41 with previous findings for mesoporous silica with various pore diameters, we obtain valuable information about the dependence of water dynamics in restricted geometries on the size of the nanoscopic confinements and the properties of the inner surfaces.

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Ma, Rui Na, Hong Chen Qiu i Jian Jun Wu. "Molecular Dynamics Simulation of the Rapid Solidification of Liquid Zinc". Advanced Materials Research 383-390 (listopad 2011): 7385–89. http://dx.doi.org/10.4028/www.scientific.net/amr.383-390.7385.

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Molecular dynamics simulation based on the Morse potential is carried out to investigate the rapid solidification of Zn. Radial distribution function, the energy analysis, Voronoi polyhedral structure analysis are used to analyze the microstructure evolution of solidification process. The results showed that amorphous structure formed when the cooling rate exceeded 2.5×1012K/s; crystal formed when the cooling rate less than 7.0×1011K/s; complex structure formed when the cooling rate was between7.0×1011K/s and 2.5×1012K/s.

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Karelin, D. L., A. V. Boldyrev, S. V. Boldyrev i A. M. Belousov. "Modeling of dynamics of vapor compression cooling system". IOP Conference Series: Materials Science and Engineering 412 (23.10.2018): 012032. http://dx.doi.org/10.1088/1757-899x/412/1/012032.

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Lee, Bong Ju, i F. Najmabadi. "Simulation of plasma-neutral dynamics for radiation cooling". Nuclear Fusion 39, nr 11 (listopad 1999): 1581–89. http://dx.doi.org/10.1088/0029-5515/39/11/309.

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Marchesi, Renzo, Manuela Maffè i Matteo Moraschi. "Computational Fluid Dynamics Analysis of Cell Cooling Process". Cell Preservation Technology 3, nr 4 (grudzień 2005): 229–37. http://dx.doi.org/10.1089/cpt.2005.3.229.

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Paul, Subhajit, i Subir K. Das. "Dynamics of clustering in freely cooling granular fluid". EPL (Europhysics Letters) 108, nr 6 (1.12.2014): 66001. http://dx.doi.org/10.1209/0295-5075/108/66001.

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Wu, Huang, Ennio Arimondo i Christopher J. Foot. "Dynamics of evaporative cooling for Bose-Einstein condensation". Physical Review A 56, nr 1 (1.07.1997): 560–69. http://dx.doi.org/10.1103/physreva.56.560.

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Suzuki, Sei. "Cooling dynamics of pure and random Ising chains". Journal of Statistical Mechanics: Theory and Experiment 2009, nr 03 (26.03.2009): P03032. http://dx.doi.org/10.1088/1742-5468/2009/03/p03032.

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Uchaikin, Vladimir V., i Renat T. Sibatov. "Subrecoil laser cooling dynamics: a fractional derivative approach". Journal of Statistical Mechanics: Theory and Experiment 2009, nr 04 (1.04.2009): P04001. http://dx.doi.org/10.1088/1742-5468/2009/04/p04001.

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Nelson, Andrew F., Willy Benz i Tamara V. Ruzmaikina. "Dynamics of Circumstellar Disks. II. Heating and Cooling". Astrophysical Journal 529, nr 1 (20.01.2000): 357–90. http://dx.doi.org/10.1086/308238.

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Navarro, Julio F., i Willy Benz. "Dynamics of cooling gas in galactic dark halos". Astrophysical Journal 380 (październik 1991): 320. http://dx.doi.org/10.1086/170590.

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Russo, L. P., i B. W. Bequette. "CSTR Performance Limitations Due to Cooling Jacket Dynamics". IFAC Proceedings Volumes 25, nr 5 (kwiecień 1992): 149–54. http://dx.doi.org/10.1016/s1474-6670(17)50984-2.

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Rosman, Gavan. "Dynamics of glass cooling applied to preform fabrication". Journal of Non-Crystalline Solids 140 (styczeń 1992): 255–58. http://dx.doi.org/10.1016/s0022-3093(05)80777-x.

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Niu, J., J. v. d. Kooi i H. v. d. Ree. "Cooling load dynamics of rooms with cooled ceilings". Building Services Engineering Research and Technology 18, nr 4 (listopad 1997): 201–7. http://dx.doi.org/10.1177/014362449701800404.

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Rosado, Mário T. S., António J. Lopes Jesus, Igor D. Reva, Rui Fausto i José S. Redinha. "Conformational Cooling Dynamics in Matrix-Isolated 1,3-Butanediol†". Journal of Physical Chemistry A 113, nr 26 (2.07.2009): 7499–507. http://dx.doi.org/10.1021/jp900771g.

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Wang, Yaning, Shuyang Qian, Yangqing Sun, Wen Wang i Jiahuan Cui. "Fast prediction and uncertainty analysis of film cooling with a semi-sphere vortex generator using artificial neural network". AIP Advances 13, nr 1 (1.01.2023): 015303. http://dx.doi.org/10.1063/5.0132989.

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The advancement of aircraft engines relies heavily on film cooling technology. To enhance the film cooling efficiency in high-pressure turbines, many passive flow control methods have been explored. Downstream of the cooling hole, a semi-sphere vortex generator (SVG) decreases the lateral dispersion of the coolant and increases the efficiency of film cooling. To better understand the influence and uncertainty of SVG parameters such as the compound angle, size, and location, a supervised learning-based artificial neural network model is developed to identify the nonlinear mapping between the input parameters and the horizontal-averaged film cooling efficiency. Training data are generated by computational fluid dynamics. The model is quite accurate and stable after sufficient testing and validation. Through Monte Carlo simulations, the framework is used to analyze the thermal and flow characteristics of the film cooling efficiency. The radius of the SVG dominates the film cooling effectiveness at low blowing ratios, whereas at comparatively large blowing ratios, the angular placement of the SVG downstream of the cooling hole is the most important element. The angular position of the SVG has a much stronger impact than the distance at both low and high blowing ratios between the cooling hole and the SVG.

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Zhong, Guo Rong, i Qiu Ming Gao. "Molecular Dynamics Simulation of the Solidification of Liquid Nickel Nanowires". Solid State Phenomena 121-123 (marzec 2007): 1053–56. http://dx.doi.org/10.4028/www.scientific.net/ssp.121-123.1053.

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Molecular dynamics simulation of the solidification behavior of liquid nickel nanowires has been carried out based on the embedded atom potential with different cooling rates. The nanowires constructed with a face-centered cubic structure and a one-dimensional (1D) periodical boundary condition along the wire axis direction. It is found that the final structure of Ni nanowires strongly depend on the cooling rates during solidification from liquid. With decreasing cooling rates the final structure of the nanowires varies from amorphous to crystalline via helical multi-shelled structure.

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Bryzgunov, M. I., V. S. Kamerdzhiev, V. V. Parkhomchuk i V. B. Reva. "Features of cooling dynamics in a high-voltage electron cooling system of the COSY". Technical Physics 60, nr 8 (sierpień 2015): 1227–33. http://dx.doi.org/10.1134/s1063784215080046.

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Xu, Ziming, Jun Xu, Zhechen Guo, Haitao Wang, Zheng Sun i Xuesong Mei. "Design and Optimization of a Novel Microchannel Battery Thermal Management System Based on Digital Twin". Energies 15, nr 4 (15.02.2022): 1421. http://dx.doi.org/10.3390/en15041421.

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In order to avoid high-temperature and large rate discharge impact on the performance of battery modules, a microchannel liquid cooling battery thermal management system (BTMS) and BTMS virtual model of the microchannel structure based on digital twin (DT) is proposed. On the basis of accurate virtual simulation model, the computational fluid dynamics (CFD) model and the Gaussian process regression algorithm were combined to drive the optimization process in order to improve the cooling capacity of the system. The results show that the microchannel plates can greatly enhance the cooling capacity of the direct cooling system and effectively improve the uniformity of the coolant. The width of the microchannel plates and the side spacing actually represent the amount of coolant flowing through the inside and outside of the battery module, which significantly impacts the maximum temperature and maximum temperature difference. Increasing the coolant flow can only effectively improve the cooling capacity of the module to a limited extent. Gaussian process regression based on the DT virtual model is more suitable for analyzing the interaction between multiple factors and obtaining global optimization results. After optimization, the maximum temperature and the maximum temperature difference of the system are reduced by 4.02 °C and 5.05 °C, respectively. The proposed structure and method are expected to provide insights into the design and development of battery thermal management systems.

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Mazzei, Lorenzo, Antonio Andreini i Bruno Facchini. "Assessment of modelling strategies for film cooling". International Journal of Numerical Methods for Heat & Fluid Flow 27, nr 5 (2.05.2017): 1118–27. http://dx.doi.org/10.1108/hff-03-2016-0086.

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Purpose Effusion cooling represents one the most innovative techniques for the thermal management of aero-engine combustors liners. The huge amount of micro-perforations implies a significant computational cost if cooling holes are included in computational fluid dynamics (CFD) simulations; therefore, many efforts are reported in literature to develop lower-order approaches aiming at limiting the number of mesh elements. This paper aims to report a numerical investigation for validating two approaches for modelling film cooling, distinguished according to the way coolant is injected (i.e. through either point or distributed mass sources). Design/methodology/approach The approaches are validated against experimental data in terms of adiabatic effectiveness and heat transfer coefficient distributions obtained for effusion cooled flat plates. Additional reynolds-averaged naver stokes (RANS) simulations were performed meshing also the perforation, so as to distinguish the contribution of injection modelling with respect to intrinsic limitations of turbulence model modelling. Findings Despite the simplified strategies for coolant injection, this work clearly shows the feasibility of obtaining a sufficiently accurate reproduction of coolant protection in conjunction with a significant saving in terms of computational cost. Practical/implications The proposed methodologies allow to take into account the presence of film cooling in simulations of devices characterized by a huge number of holes. Originality/value This activity represents the first thorough and quantitative comparison between two approaches for film cooling modelling, highlighting the advantages involved in their application.

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