Статті в журналах: "Convective mixers"

1

Shamsoddini, Rahim. "Incompressible SPH Modeling of Rotary Micropump Mixers." International Journal of Computational Methods 15, no. 04 (May 24, 2018): 1850019. http://dx.doi.org/10.1142/s0219876218500196.

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In the present study, for the first time, the flow and mass transfer in the rotary micropump-micromixers were investigated by the SPH method. In fact, the present work shows the ability of the SPH method to model the mixing process due to pumping action. The incompressible SPH method applied for modeling is improved by the kernel gradient corrective tensor, a particle shifting algorithm, and an improved periodic boundary condition. SPH is a proper method for modeling the mixing process because there is no modeling for the convective terms and so, the false diffusion is not observed in the SPH modeling. In the present study, first, a viscous micropump comprising a microchannel in which a circular cylinder rotates with special eccentricity is modeled and validated. Then, the geometry is manipulated in order to achieve a desirable micromixer.

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2

Chen, Hao, Fangfang Lou, Xueyi Zhang, Chengjun Shen, Weicheng Pan, and Shuang Wang. "Hydrothermal Conversion of Microalgae Slurry in a Continuous Solar Collector with Static Mixer for Heat Transfer Enhancement." Energies 16, no. 24 (December 9, 2023): 7986. http://dx.doi.org/10.3390/en16247986.

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The continuous solar collector is a promising heater and reactor for the hydrothermal liquefaction (HTL) of microalgae biomass. To enhance the heat transfer and hydrothermal conversion of microalgae slurry in solar-driven reactors, a static mixer is inserted in the flow channel of the solar collector. A numerical model combining CFD and HTL reactions of microalgae biomass is proposed. Six composition equations of protein, carbohydrates, lipids, biocrude, aqueous phase and biogas were proposed, while corresponding HTL kinetics were utilized to simulate the conversion rate of the reactants and products. The effects of the twist ratio of the static mixer (3–10), flow rate (30–80 L/h) and solar intensity (650, 750, 850 W/m2) on the flow resistance, heat transfer and organics formation of microalgae slurry were investigated. The swirl flow caused by the static mixer with a twist ratio of three increased the convective heat transfer coefficient (97 W·m−2·K−1) by 2.06 times, while the production rate of biocrude (0.074 g·L−1·s−1) increased by 2.05 times at 50 L/h and 750 W/m2. This investigation gives guidance for utilizing static mixers in solar-driven reactors to optimize the heat transfer and HTL of microalgae biomass with solar heat sources.

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3

Lebedev, Anatoly, Badma Salaev, Baatr Bolaev, Jury Arylov, Pavel Lebedev, and Nikolai Rybalkin. "INTENSIFICATION OF THE PROCESS OF MIXING FEED MIXTURES." SCIENCE IN THE CENTRAL RUSSIA, no. 6 (December 26, 2022): 50–59. http://dx.doi.org/10.35887/2305-2538-2022-6-50-59.

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The quality and reliability of the technological process of preparing feed mixtures has a significant role both on the properties of the manufactured product and on the productivity of animals. The use of standard mixer designs, as a rule, does not ensure the quality of mixtures, economy, efficiency and leads to an increase in energy costs for the implementation of the technological process. Despite the presence of a wide variety in mixer designs, the need for new mixer developments remains an urgent problem associated with the constant increase in requirements for the uniformity of feed mixtures. When preparing combined feeds of own production, the degree of uniformity should be 90...95%. The study of the mixing process was carried out for a two-shaft bladed mixer of continuous operation. During the research, three variants of the operation of the paddle mixer were considered, differing from each other in the number and size of the blades. The greatest intensity of mixing was in a mixer with smaller blades, but at the same time the segregation period was more than 50%. In all variants, 30...50% of the time is spent on convective mixing. High-quality mixing will be ensured by increasing the number of force impacts of the blades in the elementary mixing zones, which determine the total length of the continuous mixer. A new theoretical dependence of the mixing kinetics in a continuous-action paddle mixer is obtained. The formula shows that increasing the uniformity of the finished feed mixture can be achieved by controlling the mixing process and improving the working bodies of mixers. The efficiency of the mixing process is ensured first by creating a preliminary value of the homogeneity of the mixture Θ0, outside the mixing chamber, and then by varying the mixer parameters to ensure the required quality of the feed mixture. The obtained dependence is the basis for a new method of gravitational mixing and a device for its implementation.

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4

Yoon, Young Joon, Jae Kyung Choi, Jong Woo Lim, Hyo Tae Kim, Ji Hoon Kim, Youn Suk Choi, Jong Heun Lee, and Jong Hee Kim. "Microfluidic Devices Fabricated by LTCC Combined with Thick Film Lithography." Advanced Materials Research 74 (June 2009): 303–6. http://dx.doi.org/10.4028/www.scientific.net/amr.74.303.

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Low temperature co-fired ceramic (LTCC) process combined with thick film photolithography was employed to fabricate ceramic-based microfluidic devices. To check the applicability of novel process, three types of passive mixers, diffusion-driven T-type mixers with different channel width and convection-driven chaotic mixer, were fabricated and their microfluidic performance was evaluated. It was confirmed that the degree of mixing in ceramic-based microfluidic passive mixers was well matched with the numerical simulation data.

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5

Zhang, Lei, Jiusheng Bao, Qingjin Zhang, Yan Yin, Tonggang Liu, and Shan Huang. "Design and Simulation of a Novel Planetary Gear Mixer for Dry Particle Materials." Recent Patents on Mechanical Engineering 13, no. 4 (October 13, 2020): 387–403. http://dx.doi.org/10.2174/2212797613999200525140019.

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Background: Mixer with excellent performance is the essential premise for high-quality mixture production to ensure uniformity. In the fields of food, pharmacy, powder metallurgy and machinery industry, materials mixing is an indispensable process. At present, the mixing efficiency and performance of the traditional mixer are very low, which has its own limitations, and it is difficult to ensure the quality of the mixture, which seriously affects the safety and reliability of the mixture products such as synthetic drugs, chemical reagents, cement, synthetic fiber, etc. Objective: In order to improve the mixing performance by improving the mixing uniformity, volume utilization, reducing the mixing time and mixing blind area, a novel planetary gear mixer for dry particle materials is designed. Its blades can rotate and the angle of attack can be changed at any time, which realizes the multi-degree of freedom movement of the blades. Methods: Firstly, the shortcomings of three kinds of traditional mixers are compared and analyzed, a novel planetary gear mixer for dry particle is proposed and its structural characteristics are described. Then, the transmission system and blade parameters of the mixer are designed and calculated, and the blade parameters of the mixers are optimized based on ADAMS and EDEM. Finally, the comparative simulation experiment between planetary gear mixers and SHR-10A mixers is carried out. The experiment is used to inquiry on the mixing performance of the new planetary gear mixer. Results: The complementary cycloid was the ideal mixing trajectory of the blade. The most distinctive feature of this motion is that the attack angle of the blade can change in all directions. When the blade parameter p = 11, the Lacey index rises the fastest and the mixing degree is the largest, which indicates that the optimal mathematical model of the blade is ‘y2= 22x’. The comparison with SHR-10A mixer showed that spatial distribution of multi-degree of freedom blades in the new planetary gear mixer has strong dispersion effects on particles and better mixing performance. Conclusion: The planetary gear mixer for dry particle materials is a new type of mixer, which is composed of two sets of blades whose attack angle can be changed at any time. Convection and shear mixing dominate its mixing space, which is conducive to its rapid and full mixing, improving the mixing performance. The dry particle planetary gear mixer for dry particle materials has great developmental value and wide engineering application prospect. In this article, various patents have been discussed.

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6

Doherty, R. M., D. S. Stevenson, W. J. Collins, and M. G. Sanderson. "Influence of convective transport on tropospheric ozone and its precursors in a chemistry-climate model." Atmospheric Chemistry and Physics 5, no. 12 (December 5, 2005): 3205–18. http://dx.doi.org/10.5194/acp-5-3205-2005.

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Abstract. The impact of convection on tropospheric O3 and its precursors has been examined in a coupled chemistry-climate model. There are two ways that convection affects O3. First, convection affects O3 by vertical mixing of O3 itself. Convection lifts lower tropospheric air to regions where the O3 lifetime is longer, whilst mass-balance subsidence mixes O3-rich upper tropospheric (UT) air downwards to regions where the O3 lifetime is shorter. This tends to decrease UT O3 and the overall tropospheric column of O3. Secondly, convection affects O3 by vertical mixing of O3 precursors. This affects O3 chemical production and destruction. Convection transports isoprene and its degradation products to the UT where they interact with lightning NOx to produce PAN, at the expense of NOx. In our model, we find that convection reduces UT NOx through this mechanism; convective down-mixing also flattens our imposed profile of lightning emissions, further reducing UT NOx. Over tropical land, which has large lightning NOx emissions in the UT, we find convective lofting of NOx from surface sources appears relatively unimportant. Despite UT NOx decreases, UT O3 production increases as a result of UT HOx increases driven by isoprene oxidation chemistry. However, UT O3 tends to decrease, as the effect of convective overturning of O3 itself dominates over changes in O3 chemistry. Convective transport also reduces UT O3 in the mid-latitudes resulting in a 13% decrease in the global tropospheric O3 burden. These results contrast with an earlier study that uses a model of similar chemical complexity. Differences in convection schemes as well as chemistry schemes – in particular isoprene-driven changes are the most likely causes of such discrepancies. Further modelling studies are needed to constrain this uncertainty range.

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7

Mehrdel, Pouya, Shadi Karimi, Josep Farré-Lladós, and Jasmina Casals-Terré. "Novel Variable Radius Spiral–Shaped Micromixer: From Numerical Analysis to Experimental Validation." Micromachines 9, no. 11 (October 27, 2018): 552. http://dx.doi.org/10.3390/mi9110552.

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A novel type of spiral micromixer with expansion and contraction parts is presented in order to enhance the mixing quality in the low Reynolds number regimes for point-of-care tests (POCT). Three classes of micromixers with different numbers of loops and modified geometries were studied. Numerical simulation was performed to study the flow behavior and mixing performance solving the steady-state Navier–Stokes and the convection-diffusion equations in the Reynolds range of 0.1–10.0. Comparisons between the mixers with and without expansion parts were made to illustrate the effect of disturbing the streamlines on the mixing performance. Image analysis of the mixing results from fabricated micromixers was used to verify the results of the simulations. Since the proposed mixer provides up to 92% of homogeneity at Re 1.0, generating 442 Pa of pressure drop, this mixer makes a suitable candidate for research in the POCT field.

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8

Doherty, R. M., D. S. Stevenson, W. J. Collins, and M. G. Sanderson. "Influence of convective transport on tropospheric ozone and its precursors in a chemistry-climate model." Atmospheric Chemistry and Physics Discussions 5, no. 3 (June 7, 2005): 3747–71. http://dx.doi.org/10.5194/acpd-5-3747-2005.

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Abstract. The impact of convection on tropospheric O3 and its precursors has been examined in a coupled chemistry-climate model. There are two ways that convection affects O3. First, convection affects O3 by vertical mixing of O3 itself. Convection lifts lower tropospheric air to regions where the ozone lifetime is longer, whilst mass-balance subsidence mixes O3-rich upper tropospheric (UT) air downwards to regions where the O3 lifetime is shorter. This tends to decrease UT ozone and the overall tropospheric column of O3. Secondly, convection affects O3 by vertical mixing of ozone precursors. This affects O3 chemical production and destruction. Convection transports isoprene and its degradation products to the UT where they interact with lightning NOx to produce PAN, at the expense of NOx. The combined effect of NOx to PAN conversions and downward transport of lightning NOx results in UT NOx decreases. Convective lofting of NOx from surface sources appears relatively unimportant. Despite UT NOx decreases, UT O3 production increases as a result of UT HOx increases driven by isoprene oxidation chemistry. However, UT O3 tends to decrease, as the effect of convective overturning of O3 itself dominates over changes in O3 chemistry. The changes in tropical UT O3 are transported polewards resulting in a 15% decrease in the global tropospheric O3 burden. These results contrast with an earlier study that uses a model of similar chemical complexity. Differences in chemistry schemes - in particular isoprene-driven changes, as well as differences in convection schemes themselves, are the most likely causes of such discrepancies. Further modelling studies are needed to constrain this uncertainty range.

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9

Roxburgh, I. W. "Stellar Convective Cores." Symposium - International Astronomical Union 185 (1998): 73–80. http://dx.doi.org/10.1017/s0074180900238321.

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The internal structure of stars is governed by hydrostatic support, the distribution of the chemical elements, the transport of energy by radiation and convection, and the liberation of energy by nuclear reactions. The evolution of stars is primarily determined by the changing composition due to the nuclear burning of elements in the central parts of the star, and the redistribution of the products of these reactions by mixing processes. The dominant mixing process is convection: it governs the extent of the mixed cores in moderate and large mass main sequence stars and their subsequent evolution, it mixes nuclear processed material into the envelopes of giants affecting the composition of material ejected into the interstellar medium, thereby affecting the chemical (and luminosity) evolution of galaxies. Understanding convection is essential if one is to understand the evolution of stars. Here I am concerned with convection in stellar cores and in particular with the extension of these cores by the penetration of convective motions into the surrounding stable layers affecting the internal structure and enlarging the chemically mixed region, which in turn affects the subsequent evolution. I briefly discuss a number of approaches to this problem: isochrone fitting of clusters and binary stars; simple theoretical models, the integral constraint, numerical simulation and what we can hope to get from asteroseismological observations of individual stars and of clusters and stellar groups.

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10

Hu, Huancui, L. Ruby Leung, Zhe Feng, and James Marquis. "Moisture Recycling through Pumping by Mesoscale Convective Systems." Journal of Hydrometeorology 25, no. 6 (June 2024): 867–80. http://dx.doi.org/10.1175/jhm-d-23-0174.1.

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Abstract Moisture recycling, the contribution of local evapotranspiration (ET) to precipitation, has been studied using bulk models assuming a well-mixed atmosphere. The latter is inconsistent with a climatologically stratified atmosphere that slants across latitudes. Reconciling the two views requires an understanding of overturning associated with different weather systems. In this study, we aim to better understand moisture recycling associated with mesoscale convective systems (MCSs). Using a convection-permitting WRF simulation equipped with water vapor tracers (WRF-WVT), we tag moisture from terrestrial ET in the U.S. Southern Great Plains during May 2015, when more than 20 MCS events occurred and produced significant precipitation and flooding. Water budget analysis reveals that approximately 76% of terrestrial ET is advected away from the region while the remaining 24% of terrestrial ET is “pumped” upward within the region, accounting for 12% of precipitation. Moisture recycling peaks during early night hours (1800–2400 LT) due to the mixing of the daytime accumulated ET by active convection. By focusing on five “diurnally driven” MCSs with less large-scale circulation influence than other MCSs during the same period, we find an upright pumping of terrestrial ET at the MCS initiation and development stages, which diverges into two branches during the MCS mature and decaying stages. One branch in the upper level advects the ET-sourced moisture downstream, while the other branch in the mid-to-upper level contributes to the trailing precipitation upstream. Overall, our analysis depicts a pumping mechanism associated with MCSs that mixes local ET vertically, highlighting its specific contributions to enhancing convective precipitation processes.

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11

Kurasiński, Tomasz, Czesław Kuncewicz, and Jacek Stelmach. "Method of convective velocity determination from dissipative range of energy spectrum." Chemical and Process Engineering 33, no. 1 (March 1, 2012): 19–29. http://dx.doi.org/10.2478/v10176-012-0002-5.

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Method of convective velocity determination from dissipative range of energy spectrum In the study a new proposal of convective velocity determination necessary for eddy size determination from the dissipative range in a turbulent flow in a mixer was made. The proposed quantity depends on all the mean and fluctuating velocity components. By applying convective velocity one may determine the distribution of time and linear Taylor microscale in a stirred vessel.

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12

Huyke, Diego A., Ashwin Ramachandran, Oscar Ramirez-Neri, Jose A. Guerrero-Cruz, Leland B. Gee, Augustin Braun, Dimosthenis Sokaras, et al. "Millisecond timescale reactions observed via X-ray spectroscopy in a 3D microfabricated fused silica mixer." Journal of Synchrotron Radiation 28, no. 4 (May 19, 2021): 1100–1113. http://dx.doi.org/10.1107/s1600577521003830.

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Determination of electronic structures during chemical reactions remains challenging in studies which involve reactions in the millisecond timescale, toxic chemicals, and/or anaerobic conditions. In this study, a three-dimensionally (3D) microfabricated microfluidic mixer platform that is compatible with time-resolved X-ray absorption and emission spectroscopy (XAS and XES, respectively) is presented. This platform, to initiate reactions and study their progression, mixes a high flow rate (0.50–1.5 ml min−1) sheath stream with a low-flow-rate (5–90 µl min−1) sample stream within a monolithic fused silica chip. The chip geometry enables hydrodynamic focusing of the sample stream in 3D and sample widths as small as 5 µm. The chip is also connected to a polyimide capillary downstream to enable sample stream deceleration, expansion, and X-ray detection. In this capillary, sample widths of 50 µm are demonstrated. Further, convection–diffusion-reaction models of the mixer are presented. The models are experimentally validated using confocal epifluorescence microscopy and XAS/XES measurements of a ferricyanide and ascorbic acid reaction. The models additionally enable prediction of the residence time and residence time uncertainty of reactive species as well as mixing times. Residence times (from initiation of mixing to the point of X-ray detection) during sample stream expansion as small as 2.1 ± 0.3 ms are also demonstrated. Importantly, an exploration of the mixer operational space reveals a theoretical minimum mixing time of 0.91 ms. The proposed platform is applicable to the determination of the electronic structure of conventionally inaccessible reaction intermediates.

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13

Laurent, B. F. C., J. Bridgwater, and D. J. Parker. "Convection and segregation in a horizontal mixer." Powder Technology 123, no. 1 (February 2002): 9–18. http://dx.doi.org/10.1016/s0032-5910(01)00396-5.

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14

Chowdhury, Kakali. "MHD Mixed Convective Nanofluid Flow: Effect of Heat Source and Corrugated Boundary." Nanomedicine & Nanotechnology Open Access 8, no. 3 (2023): 1–14. http://dx.doi.org/10.23880/nnoa-16000255.

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The problem of MHD mixed convection is analyzed in a lid driven cavity with corrugated wavy bottom wall filled with Cu-H2 O nanofluid in presence of internal heat source. The top and right walls of the cavity are maintained with a uniform cold temperature whereas the left wall and bottom wavy wall are kept adiabatic. The top wall is moving with a constant velocity upon its lid and a rectangular heat source is placed horizontally inside the cavity. The physical problem is characterized by 2D governing partial differential equations along with proper boundary conditions and are discretized using Galerkin’s finite element formulation. The study is executed by analyzing different ranges of geometrical, physical and nondimensional parameters namely, wave number of wavy surface (0 ≤ ≤ λ 4) , the ratio of heat source height and cavity height 1 3 1 20 a l  ≤ ≤      volume fraction of nanoparticle (0 ≤ ≤ ϕ 0.09) Hartmann number (0 ≤ ≤ Ha 90) and Richardson number (0.1≤ ≤ Ri 10) . The results indicate that heat transfer rate decreases with the increasing value of heat source height and cavity height ratio a L       . It decreases about 9% and 25% with the increasing ratio of a L from 1 20 to 1 10 and 1 5 respectively. It also reveals that heat transfer rate increases with the increasing value of wave number of corrugated wall. At Ri=1 and Ha=0 heat transfer rate increases about 9% and 16% with the increasing value of λ from 0 to 2 and 4 respectively for nanofluid with 6% of nanoparticle. Keywords: MHD; Nanoparticle; Nanofluid

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15

Liu, Minye. "Computational study of convective–diffusive mixing in a microchannel mixer." Chemical Engineering Science 66, no. 10 (May 2011): 2211–23. http://dx.doi.org/10.1016/j.ces.2011.02.036.

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16

O Jegede, Oluwagbemiga. "Variationen der mittleren Mächtigkeit der konvektiven Mischungsschicht über Westafrika." Meteorologische Zeitschrift 3, no. 6 (December 23, 1994): 307–11. http://dx.doi.org/10.1127/metz/3/1994/307.

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17

Jia, Xiaoyu, Bingchen Che, Guangyin Jing, and Ce Zhang. "Air-Bubble Induced Mixing: A Fluidic Mixer Chip." Micromachines 11, no. 2 (February 14, 2020): 195. http://dx.doi.org/10.3390/mi11020195.

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In this study, we report the design and fabrication of a novel fluidic mixer. As proof-of-concept, the laminar flow in the main channel is firstly filled with small air-bubbles, which act as active stirrers inducing chaotic convective turbulent flow, and thus enhance the solutes mixing even at a low input flow rate. To further increase mixing efficiency, a design of neck constriction is included, which changes the relative positions of the inclusion bubbles significantly. The redistribution of liquid volume among bubbles then causes complex flow profile, which further enhances mixing. This work demonstrates a unique approach of utilizing air bubbles to facilitate mixing in bulk solution, which can find the potential applications in microfluidics, fast medical analysis, and biochemical synthesis.

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18

Yuan, Shuai, Bingyan Jiang, Tao Peng, Qiang Li, and Mingyong Zhou. "An Investigation of Flow Patterns and Mixing Characteristics in a Cross-Shaped Micromixer within the Laminar Regime." Micromachines 12, no. 4 (April 20, 2021): 462. http://dx.doi.org/10.3390/mi12040462.

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A fast mixing is critical for subsequent practical development of microfluidic devices, which are often used for assays in the detection of reagents and samples. The present work sets up computational fluid dynamics simulations to explore the flow characteristic and mixing mechanism of fluids in cross-shaped mixers within the laminar regime. First, the effects of increasing an operating parameter on local mixing quality along the microchannels are investigated. It is found that sufficient diffusion cannot occur even though the concentration gradient is large at a high Reynolds number. Meanwhile, a method for calculating local mixing efficiency is also characterized. The mixing efficiency varies exponentially with the flow distance. Second, in order to optimize the cross-shaped mixer, the effects of design parameters, namely aspect ratio, mixing angle and blockage, on mixing quality are captured and the visualization of velocity and concentration distribution are demonstrated. The results show that the aspect ratio and the blockage play an important role in accelerating the mixing process. They can improve the mixing efficiency by increasing the mass transfer area and enhancing the chaotic advection, respectively. In contrast, the inflow angle that affects dispersion length is not an effective parameter. Besides, the surface roughness, which makes the disturbance of fluid flow by roughness more obvious, is considered. Three types of rough elements bring benefits for enhancing mixing quality due to the convection induced by the lateral velocity.

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19

Konopacki, Maciej, Marian Kordas, Karol Fijałkowski, and Rafał Rakoczy. "Computational Fluid Dynamics and Experimental Studies of a New Mixing Element in a Static Mixer as a Heat Exchanger." Chemical and Process Engineering 36, no. 1 (March 1, 2015): 59–72. http://dx.doi.org/10.1515/cpe-2015-0005.

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Abstract The main aim of this work is to study the thermal efficiency of a new type of a static mixer and to analyse the flow and temperature patterns and heat transfer efficiency. The measurements were carried out for the static mixer equipped with a new mixing insert. The heat transfer enhancement was determined by measuring the temperature profiles on each side of the heating pipe as well as the temperature field inside the static mixer. All experiments were carried out with varying operating parameters for four liquids: water, glycerol, transformer oil and an aqueous solution of molasses. Numerical CFD simulations were carried out using the two-equation turbulence k-ω model, provided by ANSYS Workbench 14.5 software. The proposed CFD model was validated by comparing the predicted numerical results against experimental thermal database obtained from the investigations. Local and global convective heat transfer coefficients and Nusselt numbers were detrmined. The relationship between heat transfer process and hydrodynamics in the static mixer was also presented. Moreover, a comparison of the thermal performance between the tested static mixer and a conventional empty tube was carried out. The relative enhancement of heat transfer was characterised by the rate of relative heat transfer intensification.

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20

José, Jordi, Steven N. Shore, and Jordi Casanova. "123–321 models of classical novae." Astronomy & Astrophysics 634 (January 28, 2020): A5. http://dx.doi.org/10.1051/0004-6361/201936893.

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Context. High-resolution spectroscopy has revealed large concentrations of CNO and sometimes other intermediate-mass elements (e.g., Ne, Na, Mg, or Al, for ONe novae) in the shells ejected during nova outbursts, suggesting that the solar composition material transferred from the secondary mixes with the outermost layers of the underlying white dwarf during thermonuclear runaway. Aims. Multidimensional simulations have shown that Kelvin-Helmholtz instabilities provide self-enrichment of the accreted envelope with material from the outermost layers of the white dwarf, at levels that agree with observations. However, the Eulerian and time-explicit nature of most multidimensional codes used to date and the overwhelming computational load have limited their applicability, and no multidimensional simulation has been conducted for a full nova cycle. Methods. This paper explores a new methodology that combines 1D and 3D simulations. The early stages of the explosion (i.e., mass-accretion and initiation of the runaway) were computed with the 1D hydrodynamic code SHIVA. When convection extended throughout the entire envelope, the structures for each model were mapped into 3D Cartesian grids and were subsequently followed with the multidimensional code FLASH. Two key physical quantities were extracted from the 3D simulations and were subsequently implemented into SHIVA, which was used to complete the simulation through the late expansion and ejection stages: the time-dependent amount of mass dredged-up from the outer white dwarf layers, and the time-dependent convective velocity profile throughout the envelope. Results. This work explores for the first time the effect of the inverse energy cascade that characterizes turbulent convection in nova outbursts. More massive envelopes have been found that are those reported from previous models with pre-enrichment. These result in more violent outbursts, characterized by higher peak temperatures and greater ejected masses, with metallicity enhancements in agreement with observations.

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21

Wang, Leilei. "Analysis on Relation between Mixing Ratio and Outlet Temperature and Velocity in a Cold-Hot-Water Mixer." International Journal of Nanoscience 13, no. 05n06 (October 2014): 1460005. http://dx.doi.org/10.1142/s0219581x14600059.

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To study the relation between cold-hot-water mixing ratio and outlet-water temperature of a mixer, the geometrical model of the mixer was built. On the basis of theoretical analysis, the outlet-water temperature with different mixing ratio of cold and hot water was simulated by FLUENT software. The results show that: flow field in mixer can be divided into recirculation zone and convection zone, in which there are different thermal resistances individually, and it result in the nonlinear relation in outlet average temperature and mixing ratio; there is a linear relation between outlet average velocity and mixing ratio, which accords to the mass conservation principle of non-compressible and continuous fluid flow.

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22

Chen, Xueye, Jienan Shen, and Zengliang Hu. "Fabrication and performance evaluation of two multi-layer passive micromixers." Sensor Review 38, no. 3 (June 18, 2018): 321–25. http://dx.doi.org/10.1108/sr-04-2017-0054.

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PurposeThe purpose of this study is to provide a micromixer for achieving effective mixing of two liquids. The mixing of two liquids is difficult to achieve in microfluidic chips because they cannot form turbulence at small dimensions and velocities.Design/methodology/approachIn this paper, four kinds of passive micromixers based on splitting–recombination and chaotic convection are compared. First, a better E-shape mixing unit based on the previous F-shape mixing unit has been designed. Then, the E-shape mixing units are further combined to form three micromixers (i.e. E-mixer, SESM and FESM).FindingsFinally, the mixing experimental results show that the mixing indexes of E-mixer, SESM and FESM are more than those of F-mixer when the Reynolds number range is from 0.5 to 100. And at Re = 15, the lowest mixing index of E-mixer is 71%, which is the highest of the four micromixers.Originality/valueAt Re = 80, the highest mixing index of F-mixer and E-mixer is 92 and 94 per cent, respectively, and then it begins to decrease. But the mixing index of SESM and FESM remains close to 100 per cent.

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23

Bai, L., Q. J. Zheng, and A. B. Yu. "FEM simulation of particle flow and convective mixing in a cylindrical bladed mixer." Powder Technology 313 (May 2017): 175–83. http://dx.doi.org/10.1016/j.powtec.2017.03.018.

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Gupta, A. K., and D. Surya. "Benard-Marangoni Convection with Free Slip Bottom and Mixed Thermal Boundary Conditions." Mathematical Journal of Interdisciplinary Sciences 2, no. 2 (March 3, 2014): 141–54. http://dx.doi.org/10.15415/mjis.2014.22011.

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25

Wünsch, O., and G. Böhme. "Numerical simulation of 3d viscous fluid flow and convective mixing in a static mixer." Archive of Applied Mechanics (Ingenieur Archiv) 70, no. 1-3 (February 22, 2000): 91–102. http://dx.doi.org/10.1007/s004199900042.

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26

SHISHANOV, M. V., and CH G. COOK. "MODELING OF MIXING ELEMENTS IN MICROFLUIDICS." Herald of Technological University 27, no. 6 (2024): 94–98. http://dx.doi.org/10.55421/1998-7072_2024_27_6_94.

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Анотація:

Microfluidics (microhydrodynamics) is a science that describes the behavior of small (on the order of micro and nanoliter) volumes and flows of liquids. Microfluidic reactors are widely used in various fields of science: medicine, special chemistry, biochemistry, nuclear chemistry and many others. They are successful due to the increased mass and heat transfer, better process intensification and, as a result, high product yield. The most important elements of microreactors are the mixing zone, which provides destabilization and twisting of flows in order to mix them, and the reaction zone (serpentine channel), calculated depending on the kinetics of a particular reaction. The work is devoted to the microfluidic industry and reflects one of the most important aspects in it - mixing. Mixing in such reactors takes place in laminar mode and is carried out exclusively using molecular and convection mass transfer. The main mixers used in the framework of microreactors, such as T-shaped, Y-shaped mixers, typical mixing cells used in cascade design, have been studied. As a result of the conducted research, the most successful variants of mixers were identified, and the required microchannel length for complete mixing of the initial reagents for each of them was calculated. In order to improve the efficiency of the process, typical micromixers have been proposed, allowing to reduce the channel length required for complete mixing of reagents. The most successful micromixer was identified and cascade modeling was performed - the minimum sufficient number of cells for successful reaction was revealed. In this work, the kinetics of a specific process was not considered, the length of the reaction channel directly depends on the specific reaction.

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27

Sanglee, Kanyanee, Surawut Chuangchote, Pipat Chaiwiwatworakul, and Pisist Kumnorkaew. "PEDOT:PSS Nanofilms Fabricated by a Nonconventional Coating Method for Uses as Transparent Conducting Electrodes in Flexible Electrochromic Devices." Journal of Nanomaterials 2017 (2017): 1–8. http://dx.doi.org/10.1155/2017/5176481.

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Анотація:

Nanofilms of a polymer mixer of two ionomers, poly 3,4-ethylenedioxythiophene:poly(styrene sulfonic acid) (PEDOT:PSS), were used as conducting materials to develop transparent conducting electrodes. It was firstly found that convective deposition, a versatile and wide-area coating method, could be used for the coating and acid treatment of PEDOT:PSS films. Electrical conductivity of the PEDOT:PSS films was significantly enhanced up to 1814 S/cm by only one-time surface treatment by a mild acid solution (4 M methanesulfonic acid). This is because some PSS chains were removed out from the polymer mixer films without damage on the substrates. UV-vis-NIR spectroscopy, Raman spectroscopy, and cyclic voltammetry were used to characterize the acid-treated transparent conducting films. In this report, obtained transparent conducting PEDOT:PSS films on polyester substrates were used as flexible electrodes for fabrication of flexible electrochromic devices. Poly(3-hexylthiophene) (P3HT) was used as an active layer, which its color changed reversibly from transparent-light blue to purple with a small applied voltage (±3 V).

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28

Benkhedda, F., T. Boufendi, and S. Touahri. "Prediction of Nanofluid Forced and Mixed Convection Heat Transfer through an Annular Pipe." International Journal of Materials, Mechanics and Manufacturing 5, no. 2 (May 2017): 87–91. http://dx.doi.org/10.18178/ijmmm.2017.5.2.296.

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29

Wibisono, Andhika Feri, Yacine Addad, and Jeong Ik Lee. "ICONE23-2005 A CFD ASSESSMENT FOR MIXED CONVECTION OF NANOFLUIDS FOR NUCLEAR APPLICATION." Proceedings of the International Conference on Nuclear Engineering (ICONE) 2015.23 (2015): _ICONE23–2—_ICONE23–2. http://dx.doi.org/10.1299/jsmeicone.2015.23._icone23-2_3.

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30

Ranasinghe, Roshanka, and Charitha Pattiaratchi. "Circulation and mixing characteristics of a seasonally open tidal inlet: a field study." Marine and Freshwater Research 50, no. 4 (1999): 281. http://dx.doi.org/10.1071/mf98037.

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Анотація:

Tidal inlets in microtidal, wave-dominated coastal environments tend to close to the ocean seasonally. This obstructs navigation and could cause degradation of water quality in the estuary/lagoon connected to the inlet. Hence, engineering solutions are often implemented to prevent inlet closure. However, a prior knowledge of circulation and mixing processes within the estuary is crucial for the sustainability of any engineering solution. This paper attempts to provide insight into circulation and mixing characteristics of seasonally open estuaries based on the results of a field study undertaken at Wilson Inlet, a typical seasonally open estuary, in south-western Australia. Results of the study indicate that this type of estuary may have two distinct behavioural patterns, in winter and in summer. During winter, solar heating causes density stratification during daytime, and convective cooling causes overnight de-stratification; a horizontal cyclonic gyre is established during winter by the combined action of the Coriolis force and streamflow. During summer, strong sea breezes (~10 m s–1 ) cause vertical mixing during daytime, and convective cooling vertically mixes the water column at night. When the inlet is open, sea water propagates into the estuary during flooding tides unless streamflows are very high.

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31

Devi, Rekha, and Shilpa Sood. "Investigation of Mixed Convective Stagnated Flow of Casson Nanofluid Past an Exponentially Stretching Sheet, using the Darcy - Forchheimer Model." International Journal of Science and Research (IJSR) 12, no. 10 (October 5, 2023): 1777–85. http://dx.doi.org/10.21275/sr231023123321.

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32

Hao, Yinghai, Fang Guo, Guifang Wu, Zhanfeng Hou, Na Li, Genhao Liu, Xiafan Cui, Dezhao Meng, Yuanyuan Li, and Xiwen Li. "Numerical Simulation and Experimental Research on Heat Transfer Characteristics Based on Internal Meshing Screw." Applied Sciences 14, no. 1 (December 26, 2023): 220. http://dx.doi.org/10.3390/app14010220.

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Анотація:

The mixing and processing of high-viscosity materials play a pivotal role in composite material processing. In this context, the internal meshing screw mixer, rooted in volume extensional rheology, offers distinct advantages, including heightened mixing efficiency, exceptional material adaptability, and favorable thermomechanical properties. This research endeavors to advance our understanding of these qualities by presenting an in-depth exploration of internal meshing screw mixing. To facilitate this, an internal meshing screw mixing experimental apparatus was meticulously constructed, accompanied by extensive numerical simulations and experimental investigations into its heat transfer characteristics. Two distinct heat transfer modes are established: Mode 1 entails the transfer of the high temperature from the outer wall of the stator to the interior, while Mode 2 involves the transmission of the high temperature from the inner wall of the rotor to the exterior. The ensuing research yields several notable findings: 1. It is evident that higher rotational speeds lead to enhanced heat transfer efficiency across the board. However, among the three rotational speeds examined, 60 rpm emerges as the optimal parameter for achieving the highest heat transfer efficiency. Furthermore, within this parameter, the heat transfer efficiency is superior in Mode 1 compared to Mode 2. 2. As eccentricity increases, a corresponding decline in comprehensive heat transfer efficiency is observed. Moreover, the impact of eccentricity on heat transfer efficiency becomes increasingly pronounced over time. 3. A lower gap dimension contributes to higher heat transfer within the system. Nevertheless, this heightened heat transfer comes at the expense of reduced stability in the heat transfer process. 4. It is demonstrated that heat transfer in Mode 1 primarily follows a convection heat transfer mechanism, while Mode 2 predominantly exhibits diffusion-based heat transfer. The heat transfer efficiency of Mode 1 significantly surpasses that of Mode 2. This research substantiates its findings with the potential to enhance the heat transfer efficiency of internal meshing screw mixers, thereby making a valuable contribution to the field of polymer engineering and science.

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A.N, Maurix Mwango, Johana Sigey K, Jeconiah Okelo A, James Okwoyo M, and Kang’ethe Giterere. "A Study of Mixed Convection in an Enclosure with Different Inlet and Outlet Configurations." SIJ Transactions on Computer Networks & Communication Engineering 05, no. 01 (February 23, 2016): 10–18. http://dx.doi.org/10.9756/sijcnce/v4i1/04010040101.

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34

Huppert, Herbert E., and R. Stephen J. Sparks. "Melting the roof of a chamber containing a hot, turbulently convecting fluid." Journal of Fluid Mechanics 188 (March 1988): 107–31. http://dx.doi.org/10.1017/s0022112088000655.

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The input of a hot, turbulently convecting fluid to fill a chamber can result in the roof of the chamber melting. The rate of melting of the roof is here analysed experimentally and theoretically. Three separate cases are considered. The melt may be heavier than the fluid and initially sink through it. The intense motion in the fluid then mixes the falling melt in with it. Alternatively, the melt may be less dense than the fluid and form a separate layer between the roof and the fluid. This melt layer can itself be in quite vigorous convective motion. An intermediate case is shown to be possible, wherein the melt is initially denser than the fluid, and sinks. As its temperature increases and its density decreases, it becomes less dense than the surrounding fluid and rises. Experimental simulations of each of these three cases are described. The experiments employ a roof of either wax or ice which is melted by the aqueous salt solution beneath it. The second case, that of a light melt, has important geological applications. It describes the melting of the continental crust by the emplacement of a hot, relatively dense input of fluid basaltic rock. Both the basaltic layer and the resultant granitic melt layer crystallize and increase their viscosities as they cool. These effects are incorporated into the analysis and the rate of melting and the temperatures of the two layers are calculated as functions of time. The process is exemplified by the formation of the Cerro Galan volcanic system in Northwestern Argentina over the last 5 million years. An Appendix analyses the thermal history of the fluid in a chamber that does not melt and compares the results obtained with those derived previously.

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35

SHINOHARA, Kunio, and Sachiko SUWA. "Conceptional Design of a New Type Powder Mixer with Fluctuating Air. The Mechanism of Convective Mixing." Journal of the Society of Powder Technology, Japan 32, no. 5 (1995): 319–25. http://dx.doi.org/10.4164/sptj.32.319.

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36

Legoix, Léonard, Cendrine Gatumel, Mathieu Milhé, and Henri Berthiaux. "Analysis of powder flow and in-system rheology in a horizontal convective mixer with reclining blades." Particulate Science and Technology 36, no. 8 (July 27, 2017): 955–66. http://dx.doi.org/10.1080/02726351.2017.1331284.

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37

Amarasinghe, Widuramina, Ingebret Fjelde, Nils Giske, and Ying Guo. "CO2 Convective Dissolution in Oil-Saturated Unconsolidated Porous Media at Reservoir Conditions." Energies 14, no. 1 (January 4, 2021): 233. http://dx.doi.org/10.3390/en14010233.

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During CO2 storage, CO2 plume mixes with the water and oil present at the reservoir, initiated by diffusion followed by a density gradient that leads to a convective flow. Studies are available where CO2 convective mixing have been studied in water phase but limited in oil phase. This study was conducted to reach this gap, and experiments were conducted in a vertically packed 3-dimensional column with oil-saturated unconsolidated porous media at 100 bar and 50 °C (representative of reservoir pressure and temperature conditions). N-Decane and crude oil were used as oils, and glass beads as porous media. A bromothymol blue water solution-filled sapphire cell connected at the bottom of the column was used to monitor the CO2 breakthrough. With the increase of the Rayleigh number, the CO2 transport rate in n-decane was found to increase as a function of a second order polynomial. Ra number vs. dimensionless time τ had a power relationship in the form of Ra = c×τ−n. The overall pressure decay was faster in n-decane compared to crude oil for similar permeability (4 D), and the crude oil had a breakthrough time three times slower than in n-decane. The results were compared with similar experiments that have been carried out using water.

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38

Salamat, Jaber, and Bülent Genç. "Numerical Simulation of Granular Flow in Concrete Batching Plant via Discrete Element Method." European Journal of Research and Development 3, no. 2 (May 12, 2023): 11–28. http://dx.doi.org/10.56038/ejrnd.v3i2.219.

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A new giant concrete batching plant with the production capacity of 270m3/hr was designed, analyzed and fabricated. In this concrete batching plant, the granular materials used for high-quality products must be uniformly mixed to attain a homogenous mixture. For this, the discrete element method (DEM) was utilized to simulate the filling, mixing, and discharging processes. The Hertz-Mindlin, elastic-plastic spring-dashpot and Simplified Johnson-Kendall-Roberts (SJKR) models were used for the interaction rules among granular particles. In the light of the aforementioned models, the first simulation with different particle sizes and the second simulation with monosized particles were realized. In the first simulation, the segregation by percolation and momentum segregation were perceived during the bunker filling stage, as well as the seeded granulation, which occurred in the mixer when the radii of particles were not monosized. Furthermore, in the second simulation, convective, diffusive and shear mixing mechanisms were observed and consequently the quantification of the mixing index was calculated using the lacey and miles statistical methods. At last, the active regions formed in the mixer were investigated by taking the velocity of the particles as reference during the mixing stages as well as the mixture throughput from the transfer chute.

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39

Shi, Liuyong, Hanghang Ding, Xiangtao Zhong, Binfeng Yin, Zhenyu Liu, and Teng Zhou. "Mixing Mechanism of Microfluidic Mixer with Staggered Virtual Electrode Based on Light-Actuated AC Electroosmosis." Micromachines 12, no. 7 (June 24, 2021): 744. http://dx.doi.org/10.3390/mi12070744.

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In this paper, we present a novel microfluidic mixer with staggered virtual electrode based on light-actuated AC electroosmosis (LACE). We solve the coupled system of the flow field described by Navier–Stokes equations, the described electric field by a Laplace equation, and the concentration field described by a convection–diffusion equation via a finite-element method (FEM). Moreover, we study the distribution of the flow, electric, and concentration fields in the microchannel, and reveal the generating mechanism of the rotating vortex on the cross-section of the microchannel and the mixing mechanism of the fluid sample. We also explore the influence of several key geometric parameters such as the length, width, and spacing of the virtual electrode, and the height of the microchannel on mixing performance; the relatively optimal mixer structure is thus obtained. The current micromixer provides a favorable fluid-mixing method based on an optical virtual electrode, and could promote the comprehensive integration of functions in modern microfluidic-analysis systems.

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40

Abou-Ziyan, Hosny, Reda Ameen, and Khairy Elsayed. "Fluid flow and convection heat transfer in concentric and eccentric cylindrical annuli of different radii ratios for Taylor-Couette-Poiseuille flow." Advances in Mechanical Engineering 13, no. 8 (August 2021): 168781402110407. http://dx.doi.org/10.1177/16878140211040731.

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Анотація:

This paper presents the results of fluid flow and convection heat transfer in concentric and eccentric annuli between two cylinders using a three-dimensional computational fluid dynamics model. Effects of rotational speed ( n = 0, 150, 300, and 400 rpm) and eccentricity (ε = 0, 0.15, 0.3, 0.45, and 0.6) on axial and tangential velocity distribution, pressure drop and forced convection heat transfer are investigated for radii ratios (η) of 0.2, 0.4, 0.6, and 0.8, Reynolds number 2.0 × 103–1.236 × 105, Taylor number 1.47 × 106–1.6 × 1010, and Prandtl number 3.71–6.94. The parameters cover many applications, including rotary heat exchangers, mixers, agitators, etc. Nusselt numbers and friction factors for stationary and rotated concentric and eccentric annuli are correlated with four dimensionless numbers. The results revealed that when the speed of the inner cylinder increases from 0 to 400 rpm, the friction factor increases by 7.7%–103% for concentric and 8.2%–148% for eccentric annuli, whereas Nusselt number enhances by 37%–333% for concentric and 44%–340% for eccentric annuli. The radius ratio has a substantial effect on the heat transfer and pressure drop in annuli. The eccentricity enhances the heat transfer up to 12%, whereas its effect on the friction factor is not monotonic as it depends on Reynolds number, radii ratios, and rotational speed.

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41

Kostanyan, Artak E., Vera V. Belova, and Andrey A. Voshkin. "Three- and Multi-Phase Extraction as a Tool for the Implementation of Liquid Membrane Separation Methods in Practice." Membranes 12, no. 10 (September 25, 2022): 926. http://dx.doi.org/10.3390/membranes12100926.

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Анотація:

To promote the implementation of liquid membrane separations in industry, we have previously proposed extraction methods called three- and multi-phase extraction. The three-phase multi-stage extraction is carried out in a cascade of bulk liquid membrane separation stages, each comprising two interconnected (extraction and stripping) chambers. The organic liquid membrane phase recycles between the chambers within the same stage. In multi-phase extraction, each separation stage includes a scrubbing chamber, located between the extraction and stripping chambers. The three- and multi-phase multi-stage extraction technique can be realized either in a series of mixer–settler extractors or in special two- or multi-chamber extraction apparatuses, in which the convective circulation of continuous membrane phase between the chambers takes place due to the difference in emulsion density in the chambers. The results of an experimental study of the extraction of phenol from sulfuric acid solutions in the three-phase extractors with convective circulation of continuous membrane phase are presented. Butyl acetate was used as an extractant. The stripping of phenol from the organic phase was carried out with 5–12% NaOH aqueous solutions. The prospects of using three-phase extractors for wastewater treatment from phenol are shown. An increase in the efficiency of three-phase extraction can be achieved by carrying out the process in a cascade of three-phase apparatuses.

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42

SHTERN, VLADIMIR, and FAZLE HUSSAIN. "Generation of collimated jets by a point source of heat and gravity." Journal of Fluid Mechanics 449 (December 10, 2001): 39–59. http://dx.doi.org/10.1017/s0022112001006097.

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Анотація:

New solutions of the Boussinesq equations describe the onset of convection as well as the development of collimated bipolar jets near a point source of both heat and gravity. Stability, bifurcation, and asymptotic analyses of these solutions reveal details of jet formation. Convection (with l cells) evolves from the rest state at the Rayleigh number Ra = Racr = (l − 1)l(l + 1)(l + 2). Bipolar (l = 2) flow emerges at Ra = 24 via a transcritical bifurcation: Re = 7(24 − Ra)/(6 + 4Pr), where Re is a convection amplitude (dimensionless velocity on the symmetry axis) and Pr is the Prandtl number. This flow is unstable for small positive values of Re but becomes stable as Re exceeds some threshold value. The high-Re stable flow emerges from the rest state and returns to the rest state via hysteretic transitions with changing Ra. Stable convection attains high speeds for small Pr (typical of electrically conducting media, e.g. in cosmic jets). Convection saturates due to negative ‘feedback’: the flow mixes hot and cold fluids thus decreasing the buoyancy force that drives the flow. This ‘feedback’ weakens with decreasing Pr, resulting in the development of high-speed convection with a collimated jet on the axis. If swirl is imposed on the equatorial plane, the jet velocity decreases. With increasing swirl, the jet becomes annular and then develops flow reversal on the axis. Transforming the stability problem of this strongly non-parallel flow to ordinary differential equations, we find that the jet is stable and derive an amplitude equation governing the hysteretic transitions between steady states. The results obtained are discussed in the context of geophysical and astrophysical flows.

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43

Shah, Imran, Han Su Jeon, Muhsin Ali, Doh Hoi Yang, and Kyung-Hyun Choi. "Optimal parametric mixing analysis of active and passive micromixers using Taguchi method." Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering 233, no. 6 (August 6, 2019): 1292–303. http://dx.doi.org/10.1177/0954408919862997.

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Анотація:

Mixing of fluids flowing through channels and chambers is a crucial step in chemical and biochemical reactions inside microfluidic devices due to laminar flow because of small size channel and chamber dimensions. Mixing can be enhanced by passive or active mechanism which makes convection dominant over diffusion. To address this challenge, the study proposes three novel mixing designs: passive mixer, active mixer and a combination of active and passive mixing. These designs mixing performance has been studied by numerical simulation using COMSOL 5.3. According to the preliminary results of the study, pure active micromixer design has superior mixing ability. The mixing ability was proved by concentration line plots, concentration contours and videos. In order to further optimize the mixing index of the pure active micromixer, Taguchi method is applied against various input parametric values for micromixer such as frequency, voltage and velocity. The velocity is required for two fluids to flow, while frequency and voltages are for providing an external energy for active mixing. A total of nine cases were analyzed; the two best cases out of nine were selected for comparing mixing index line plots. The result of the study conclude that pure active micro-mixer at an optimal set of parameters, frequency of 10 Hz, velocity of 0.05 mm s–1 and voltage of 0.5 V achieved 99.6% mixing index at t = 0.2 s.

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Zhang, He, Xin Li, Rongyan Chuai, and Yingjie Zhang. "Chaotic Micromixer Based on 3D Horseshoe Transformation." Micromachines 10, no. 6 (June 14, 2019): 398. http://dx.doi.org/10.3390/mi10060398.

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Анотація:

To improve the efficiency of mixing under laminar flow with a low Reynolds number (Re), a novel three-dimensional Horseshoe Transformation (3D HT) was proposed as the basis for the design of a micromixer. Compared with the classical HT, the Lyapunov exponent of the 3D HT, which was calculated based on a symbolic dynamic system, proved the chaotic enhancement. Based on the 3D HT, a micromixer with a mixing length of 12 mm containing six mixing units was obtained by sequentially applying “squeeze”, “stretch”, “twice fold”, “inverse transformation”, and “intersection” operations. Numerical simulation and Peclet Number (Pe) calculations indicated that when the squeeze amplitude 0 < α < 1/2, 0 < β < 1/2, the stretch amplitude γ > 4, and Re ≥ 1, the mass transfer in the mixer was dominated by convective diffusion induced by chaotic flow. When Re = 10, at the outlet of the mixing chamber, the simulated mixing index was 96.4%, which was far less than the value at Re = 0.1 (σ = 0.041). Microscope images of the mixing chamber and the curve trend of pH buffer solutions obtained from a mixing experiment were both consistent with the results of the simulation. When Re = 10, the average mixing index of the pH buffer solutions was 91.75%, which proved the excellent mixing efficiency of the mixer based on the 3D HT.

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45

Abdullah, Rand, Vladimir Agranat, Michael Malin, and Igor Pioro. "ICONE23-1108 CFD PREDICTION OF MIXED-CONVECTION HEAT TRANSFER IN SUPERCRITICAL WATER IN A BARE TUBE." Proceedings of the International Conference on Nuclear Engineering (ICONE) 2015.23 (2015): _ICONE23–1—_ICONE23–1. http://dx.doi.org/10.1299/jsmeicone.2015.23._icone23-1_58.

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46

Ould-Amer, Y. "3D Fully Developed Laminar Mixed Convection in Horizontal Concentric Annuli with the Presence of Porous Blocks." International Journal of Engineering and Technology 8, no. 2 (February 2016): 76–82. http://dx.doi.org/10.7763/ijet.2016.v6.862.

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47

Ould-Amer, Y. "3D Fully Developed Laminar Mixed Convection in Horizontal Concentric Annuli with the Presence of Porous Blocks." International Journal of Engineering and Technology 8, no. 2 (February 2016): 76–82. http://dx.doi.org/10.7763/ijet.2016.v8.862.

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48

Sivetskyi, Volodymyr, Oleksandr Sokolskyi, and Oleksiy Malchevskyi. "Modeling of mixing process of the polymer composition in the dynamic mixer of the worm extruder." Proceedings of the NTUU “Igor Sikorsky KPI”. Series: Chemical engineering, ecology and resource saving, no. 2 (June 30, 2023): 53–59. http://dx.doi.org/10.20535/2617-9741.2.2023.283524.

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Анотація:

Mixing processes play an important role in the processing of polymer materials, because the quality of the mixing of the polymer material depends on its level of homogeneity, which in turn affects the quality of the final product. It is another matter when the polymer material consists of two or more components, in this case, the issue of the process of obtaining a homogeneous polymer composition becomes extremely acute. In order to improve the quality of the final product and justify the design and technological parameters of the mixing zone, it is necessary to investigate the regularity of the quality of mixing in a dynamic mixer of the CTM worm extruder type. According to existing works on determining the quality of mixing of polymeric material, the difference in concentrations of one of the components in different cross-sections along the length of the channel can be used as a criterion for homogeneity of mixing. Numerical modeling of the process of mixing the polymer composition in the dynamic mixer installed in the dosing zone of the worm extruder, which is equipped with an additional injection device that supplies the additional component to the dynamic mixing zone through the injection channel located in the body of the worm extruder, was carried out. Calculations were carried out on the basis of the finite element method (FEM) using the ANSYS software complex. A mathematical model of the process of mixing the polymer composition in a dynamic mixer of the CTM type of a worm extruder with the addition of an additional component, which is identical in density and viscosity to the main polymer material and can differ only in a certain feature that does not affect the properties of the components, such as color, has been developed. Moreover, the properties were set in such a way that the temperature distribution of the mixture was completely determined by the convective component, that is, it resulted only from the conditions of the mechanical movement of the volumes of the components. The dependence of the homogeneity of the polymer composition as a result of mixing on the technological and design parameters of the dynamic mixer of the CTM type was obtained. The research was carried out at different speeds of rotation of the mixer rotor and at different speeds of supplying the additional component. The movement of the components of the mixture was determined by their flow rate at the entrance to the main channel and at the entrance to the additional injection channel. The most optimal technical characteristics were selected in order to achieve the best level of uniformity.

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49

Jakubovičová, Lenka, Milan Sága, and Marián Handrik. "Numerical analysis of stiffener for hybrid drive unite." MATEC Web of Conferences 157 (2018): 02015. http://dx.doi.org/10.1051/matecconf/201815702015.

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Анотація:

The matter of this article is a stress-strain analysis of hybrid drive prototype unit connected directly to convention Concrete Transit Mixer Gearbox. The unite was developed with intention to do field test on existing convection machines with possibility to use existing interfaces. The hybrid drive unit consists from electric and hydrostatic motor connected through addition mechanical transmission gearbox. The question is if today standard interface is good enough or need additional support a “stiffener”. Two engineering design were analysed. The first one includes using the stiffener to fixate the construction of hybrid drive unite connected to the planetary gear. The second one is without the stiffener. For strain-stress analysis, a finite element software ANSYS Workbench was used.

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50

Sijikumar, S., and K. Rajeev. "Role of the Arabian Sea Warm Pool on the Precipitation Characteristics during the Monsoon Onset Period." Journal of Climate 25, no. 6 (March 14, 2012): 1890–99. http://dx.doi.org/10.1175/jcli-d-11-00286.1.

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Abstract Regional distribution of precipitation during the onset phase of the Indian summer monsoon (15 May–15 June) shows distinct patterns in the years 2009 and 2010, with the latter having considerably more precipitation over the southeast Arabian Sea (AS) and the west coast of peninsular India. During these years, the location and regional extent of the warm pool in the AS are also distinct. In 2009, the warm pool core is located in the equatorial region, whereas in 2010 it spreads to a wide region of the AS. Sensitivity experiments with different SST forcings have been carried out using the Weather Research and Forecasting (WRF) model to understand the influence of the AS warm pool on the monsoon onset precipitation characteristics. Simulations with actual SSTs in the AS and climatological SSTs elsewhere are able to reproduce the distinct behavior of the monsoon onset precipitation observed during 2009 and 2010. These simulations show suppressed convection over the central and northern AS in 2009, while warmer SSTs in the AS favor enhanced convection during 2010 combined with a sharp contrast in the moisture transport. The strong intrusion of drier air from the north AS effectively confines the moist air mass from the south, causing a net transport of moisture toward the southwest coast of peninsular India and leads to positive anomalies in precipitation over the region in 2010. However, during 2009, the drier air from the north mixes rather easily over the AS, which suppress the convection.

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Статті в журналах з теми "Convective mixers"

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