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In this paper, we focus on the two-dimensional pulsating nanofluid flow through a parallel-plate channel in the presence of a magnetic field. The pulsating flow is produced by an applied pressure gradient that fluctuates with a small amplitude. A kind of proper transformation is used so that the governing equations describing the momentum and thermal energy are reduced to a set of non-dimensional equations. The analytical expressions of the pulsating velocity, temperature, and Nusselt number of nanofluids are obtained by the perturbation technique. In the present study, the effects of the Cu-H2O and Al2O3-H2O nanofluids on the flow and heat transfer in pulsating flow are compared and analyzed. The results show that the convective heat transfer effect of Cu-H2O nanofluids is better than that of Al2O3-H2O nanofluids. Also, the effects of the Hartmann number and pulsation amplitude on the velocity, temperature, and Nusselt number are examined and discussed in detail. The present work indicates that increasing the Hartmann number and pulsation amplitude can enhance the heat transfer of the pulsating flow. In addition, selecting an optimal pulsation frequency can maximize the convective heat transfer of the pulsating flow. Therefore, improved understanding of these fundamental mechanisms is conducive to the optimal design of thermal systems. [ABSTRACT FROM AUTHOR]

Flow and heat transfer of a nanofluid through a horizontal microchannel in the presence of the magnetic field effects and electric double layer (EDL) is investigated theoretically. For a microchannel with a large aspect ratio, the flow problem is treated as a two-dimensional nonlinear system. The body force generated by the EDL and magnetic field is considered in momentum equation. In order to study the mechanism of nanofluid heat transfer, the nanoparticles distribution and the heat transfer process of nanofluid flow are represented by the Buongiorno's nanofluid model with the passively controlled nanoparticles distribution at the boundary, which has not been considered in previous microchannel studies. Compared to the so-called active control of nanoparticle volume fraction at the boundary, the current approach makes the model physically more reliable by taking into account of the effect due to varying temperature. The analytical approximations obtained by the homotopy analysis method reveals that both the magnetic field effects and the EDL play significant roles on altering the flow and heat transfer in microchannels. It is also found that the heat enhancement is significantly depend on the Brinkman number and the temperature applied to the wall. [ABSTRACT FROM AUTHOR]

Electrolysis of water offers an efficient and eco-friendly route to separate hydrogen isotopes and cathode electrocatalysts featuring high separation factors coupled with high activity and stability are increasingly in demand. In this work, we propose MoS 2 rich in edge sites (MoS 2 -RS) as a promising hydrogen isotope separation electrocatalyst for the first time. MoS 2 -RS cathode exhibits high activity and hydrogen isotope selectivity with a low overpotential of 182.4 mV at 10 mA cm−2, a small Tafel slope of 61 mV dec−1 and a high hydrogen-deuterium separation factor (S H/D) of 10.22 in contrast to 6.33 for the commercial Pt/C catalyst. Density functional theory calculations ascribe the high selectivity of MoS 2 -RS to the H/D zero-point energy difference. Moreover, MoS 2 -RS demonstrates much higher values of S H/D compared with Pt/C catalyst under all test conditions and good long-term stability under acidic conditions. This work not only provides a promising catalytic material for efficient electrolytic separation of hydrogen isotopes but also indicates the direction of rational design of it. [Display omitted] [ABSTRACT FROM AUTHOR]

The behaviour of microchannel flow of a nanofluid between two parallel flat plates in the presence of the electrical double layer (EDL) is investigated in this paper. The problem is formulated based on the Buongiorno nanofluid model with the electrical body force due to the EDL being considered in the momentum equation. As one of the highlights of the present investigation, the unphysical assumption introduced in previous studies often leading to the discontinuities of flow field that the electrostatic potential in the middle of the channel has to be equal to zero is eliminated. In addition, the inappropriate assumption that the pressure constant is treated as a known condition is also rectified. The new model is developed with the governing equations being reduced by a set of dimensionless quantities to a set of coupled ordinary differential equations. Based on the analytical approximations, the influences of various physical parameters on the flow field and temperature field, and the important physical quantities of practical interests are analysed and discussed in detail. [ABSTRACT FROM AUTHOR]

The time-dependent mixed bioconvection flow of an electrically conducting fluid between two infinite parallel plates in the presence of a magnetic field and a first-order chemical reaction is investigated. The fully coupled nonlinear systems describing the total mass, momentum, thermal energy, mass diffusion, and microorganisms equations are reduced to a set of ordinary differential equations via a set of new similarity transformations. The detailed analysis illustrating the influences of various physical parameters such as the magnetic, squeezing, and chemical reaction parameters and the Schmidt and Prandtl numbers on the distributions of temperature and microorganisms as well as the skin friction and the Nusselt number is presented. The conclusion is drawn that the flow field, temperature, and chemical reaction profiles are significantly influenced by magnetic parameter, heat generation/absorption parameter, and chemical parameter. Some examples of potential applications of such bioconvection could be found in pharmaceutical industry, microfluidic devices, microbial enhanced oil recovery, modeling oil, and gas-bearing sedimentary basins. [ABSTRACT FROM AUTHOR]

It is a complex process for a vehicle to emerge from the water. During this period, the cavitation flow state and the load on the vehicle change sharply, which has a great impact on the movement of the vehicle. It is necessary to study the cavitation flow state and loading characteristics during the process of water-exit. At present, the research on this aspect at home and abroad mostly focuses on the use of commercial software or self-written programs to simulate the pressure distribution on the surface of the extended vehicle and the flow field at the head of the vehicle during the process of water exit. However, there is a lack of relevant experimental data on the changes of pressure and cavitation flow regimes during the water-exit process of different head-shaped vehicles. The research on water plumes mostly focuses on the interaction between the explosion bubble and the free surface, but there is little research on the water plumes generated when different head-shaped vehicles exit the water. Based on this, this paper designs a set of surface pressure load measurement system for the water-exit process of the vehicle under the decompression environment, and designs and processes the vehicle with different head types such as cone head, hemispheric head, and swelling conical head. The flow characteristics and pressure loads of different head-shaped vehicles in the initial stage, development stage and collapse stage of cavitation were studied. The study found that the shape of the vacuoles in the initial stage, the development stage and the collapse stage of different head-shaped vehicles is quite different, and the change process of the pressure is also different; In addition, the water plumes generated when the vehicle is out of water can be divided into three categories according to the collapse method, and the collapse time of each type are also different. •The cavitation flow characteristics and pressure changes of different head-shaped vehicles in the process of underwater vertical motion were explored by experimental methods •Three different types of water mounds are proposed when the vehicle emerges from the water, and are explored by means of experiments. •Using the pressure sensor to record the pressure changes of the vehicle during the underwater movement phase and the water exit phase. •The contour of the cavitation bubble is more accurately extracted by using the boundary recognition program [ABSTRACT FROM AUTHOR]

The cavitation generated during the water-exit process of the vehicle will have a great influence on the water exit attitude and stability of the vehicle. At present, the research on the cavitation flow mainly focuses on the single vehicle, and there is little research on the cavitation flow during the water-exit process of the double vehicles. However, in practical applications, it often happens that the double vehicles emerge from the water at different timings. Therefore, it is necessary to study the flow characteristics of the cavitation of the vehicles. In this paper, a set of underwater vertical launching experiment device of double vehicles under decompression condition is designed. Based on this device, different time sequence water-out experiments of the vehicles are carried out, and multiple high-speed cameras are used to record the whole process of the vehicles from different angles. The effect of launch velocity, environmental pressure, and lateral and vertical distances on cavitation morphological changes and sizes are explored. Studies have shown that there will be a certain degree of interference between the two vehicles during the water-exit process. When the launch speed increases and the environmental pressure decreases, the size of the cavitation when the double vehicles exit the water will increase greatly, and gradually move closer to the single vehicle; When the lateral and vertical distances increase, the interference between the vehicles will be weakened. • The characteristics of cavitation bubbles in vertical water-exit of two-lunched vehicle are investigated by experinmental method. • The process diagram of the development of cavitation flow during the water outlet process of the two-lunched vehicle is obtained. • The of environmental pressure, lateral and vertical distance, and launch speed on the shape change process of the cavitation was observed. [ABSTRACT FROM AUTHOR]

In this paper, the three-dimensional nanofluid bio-convection near a stagnation attachment is studied. With a set of similarity variables, the governing equations embodying the conservation of total mass, momentum, thermal energy, nanoparticles and microorganisms are reduced to a set of fully coupled nonlinear differential equations. The homotopy analysis method (HAM)-finite difference method (FDM) technique is used to obtain exact solutions. The effect of various physical parameters on distribution of the motile microorganisms and the important physical quantities of practical interests are presented and discussed. [ABSTRACT FROM AUTHOR]

In this paper, an investigation is made of the three-dimensional flow and heat transfer of a nanofluid in the boundary-layer region over a flat sheet stretched continuously in two lateral directions. With the help of a series of similarity transformations, this problem is reduced to a set of three coupled differential equations. The homotopy analysis method (HAM) is then applied to derive the explicit solutions for both the velocity and the temperature distributions. A mathematical analysis shows that these solutions decay exponentially at far field. Besides, the influences of the nanoparticle volume fraction ϕ on the velocity and temperature profiles, as well as the reduced local skin friction coefficients and the reduced local Nusselt numbers are studied. It is found that the heat transfer conductivity of the nanofluid is superior to that of the pure fluids. [ABSTRACT FROM AUTHOR]

In this study, we consider the ideal fluid model of an inviscid fluid, assuming that the fluid motion is adiabatic; the flow is irrotational, that is, the individual fluid particles do not rotate; vorticity ω ̃ = 0 ; and the flow is incompressible, in which the density of fluid particles does not vary significantly with fluid motion and can be considered constant throughout the fluid volume and throughout the motion. We start with equations representing continuity, conservation of momentum, conservation of entropy, and streamline equations, respectively. It is then reduced to a standard system of equations describing motion in two dimensions, defined by the Laplace equation with appropriate kinematic and dynamic boundary conditions, in terms of velocity potential and surface elevation. Finally, the one-dimensional nonlinear Korteweg–De Vries (KdV) equation is derived. Then, we further investigate the interaction of multiple periodic waves using the KdV equation and explain the interaction wave energy transfer procedure between the primary and higher order harmonics, and the Phillips ["On the dynamics of unsteady gravity waves of finite amplitude. I. The elementary interactions," J. Fluid Mech. 9, 193–217 (1960)] wave resonance criterion is employed for capturing the periodic wave interaction whose energy conversion is analyzed via Fourier spectra. It is also found that for solitons, multiple collisions of different solitons eventually regain their original shape and that higher-energy solitons have faster velocities than lower-energy solitons, which, to the best of our knowledge, is overlooked. [ABSTRACT FROM AUTHOR]

Based on the importance of barbaloin (Bar), development of efficient sensing methods in barbaloin detection has remarkable function and practical significance. In this work, copper nanoclusters (Cu NCs) with good water‐soluble character were prepared by one‐pot way and successfully used for selective detection of barbaloin. The stable probe with uniform size was protected by glutathione (GSH) and reduced by ascorbic acid (AA). Intriguingly, fluorescence of GSH−Cu NCs was quenched by barbaloin. The static quenching and inner filter effect (IFE) was supposed to main quenching mechanism. Furthermore, GSH−Cu NCs could well distinguish barbaloin from possible interferes and exhibited linear relationship of barbaloin concentrations from 3 to 100 μM. Significantly, satisfactory recovery experiments were successfully operated in bovine serum samples for barbaloin sensing. This probe with superior fluorescence properties provided better choice for barbaloin detection. [ABSTRACT FROM AUTHOR]

Corrosion products, such as 110 mAg, 58Co, 60Co, 51Cr, 54Mn and 125Sb have great contribution to the radioactivity of primary coolant in nuclear power plant (NPP). It is considered that some of these nuclides are probably in colloidal form, since they cannot be effectively removed by the conventional ion exchange process in NPP. In this paper, the chemical speciation and behavior of these nuclides in the primary coolant was investigated by simulation calculation and validation experiments. In the reductive circumstance of primary coolant during power operation and re-operation preparatory stage in a normal operation process of reactor, nuclides such as 51Cr, 54Mn, 58Co and 60Co are mainly present as ions of Mn2+ and Cr2+, as well as Co2+ with the possibility of forming Co(OH) n 2-n colloid in a high activity. Meanwhile, 110 mAg can be reduced to Ag0 with a form of nano-silver cluster or nano-silver metal particles in a size of 10–100 nm, and 125Sb mainly exists in the form of soluble anion SbO 2 - or hydrolyzed granular Sb 2 O 3. During shutdown oxidation process, 110 mAg and 125Sb can be oxidized by the added hydrogen peroxide into Ag+ ions and anion SbO 3 - leading to an increased solubility in coolant. Meanwhile 51Cr and 54Mn can be oxidized into Cr(III) and Mn (IV), which can form the co-existing state of many hydroxyl complexes, such as Cr(OH)n3-n, Mn(OH) n 4-n or MnO 2. It indicated that metallic silver particles Ag0 and some metal hydrated hydroxide, such as Co(OH)n2-n, Cr(OH) n 3-n and Mn(OH) n 4-n may be responsible for the formation of colloids in the primary coolant. • Ag exists mainly as Ag0 particles in size of 10–100 nm in primary coolant. • 110 mAg emission increase since Ag0 is oxidized into Ag+ by H 2 O 2 in shutdown process. • Colloids of Co(OH)n2-n, Cr(OH) n 3-n and Mn(OH) n 4-n may be formed in core coolant. • Sb mainly exists in SbO 2 - or hydrolyzed granular Sb 2 O 3 at power operation stage. • Anion SbO 3 - is formed in shutdown process due to the oxidation by H 2 O 2 in coolant. [ABSTRACT FROM AUTHOR]

We consider the fully developed mixed convection flow in a vertical channel driven by an external pressure gradient and buoyancy force. Unlike in previous studies, we employ a new model to formulate the flow problem that guarantees the smoothness and continuity of the distributions of the electrical potential and velocity. This model, solved by the homotopy analysis method, is compatible with the channel flow models commonly used in fluid mechanics. [ABSTRACT FROM AUTHOR]

To properly manage nuclear wastes is critical to sustainable utilization of nuclear power and environment health. Here, we show an innovative carbiding strategy for sustainable management of radioactive graphite through digestion of carbon in H 2 O 2. The combined action of intermolecular oxidation of graphite by MoO 3 and molybdenum carbiding demonstrates success in gasifying graphite and sequestrating uranium for a simulated uranium-contaminated graphite waste. The carbiding process plays a triple role: (1) converting graphite into atomic carbon digestible in H 2 O 2 , (2) generating oxalic ligands in the presence of H 2 O 2 to favor U-precipitation, and (3) delivering oxalic ligands to coordinate to MoVI-oxo anionic species to improve sample batching capacity. We demonstrate > 99% of uranium to be sequestrated for the simulated waste with graphite matrix completely gasifying while no detectable U-migration occurred during operation. This method has further been extended to removal of surface carbon layers for graphite monolith and thus can be used to decontaminate monolithic graphite waste with emission of a minimal amount of secondary waste. We believe this work not only provides a sustainable approach to tackle the managing issue of heavily metal contaminated graphite waste, but also indicates a promising methodology toward surface decontamination for irradiated graphite in general. [Display omitted] • Graphite is converted into atomic carbon digestible in H 2 O 2 via reaction with MoO 3. • In situ generated oxalic ligands in H 2 O 2 favors uranium precipitation. • Carbide layers generate on graphite monolith (GM) via surface inward Mo carbiding. • Carbide layers are etched off through oxidative digestion in H 2 O 2. • Injected B and Ce within surface region of GM are released in H 2 O 2. [ABSTRACT FROM AUTHOR]