Volume Fraction Of Solid Particles Research Articles

Effects of using a finned cylindrical cooler in the nano-enhanced cooling channel on the exergetic performance of a PV/TEG-coupled system

ABSTRACT In this study, three different nano-enhanced channel models were integrated into the 3D photovoltaic (PV)/thermoelectric generator (TEG) system and the effect of the channel models on the PV/TEG system performance was examined. The flat rectangular channel, Model 1 while the cylindrical and fin-reinforced cylindrical object accommodated in the flat rectangular channel are defined as Model 2 and Model 3, respectively. A comparison of water and ternary nanofluid with various nanoparticle (solid particle volume fraction between 0.01 and 0.03) loading was performed in each channel model. In addition, impacts of cooling fluids at different inlet temperatures (Tg between 25°C and 12.5°C) were considered in the simulations. Among different cooling channels, lowest PV cell temperature and the highest PV output power were obtained in Model 3. The highest PV power (0.51 W) was obtained with Model 3 with ternary nanofluid (%3 volume fraction) at Tg = 12.5°C. This value is is 3.66% and 4.03% higher than Model 2 and Model 1, respectively. Under the same conditions, TEG output power reached its highest value with Model 2 and it was followed by Model 1 and Model 3, respectively. With the reinforcement of fins to the cylindrical object, an improvement in thermal performance was achieved, but a decrease in total output power was observed.

Particle-assisted formation of oil-in-liquid metal emulsions.

Gallium-based liquid metals (LM) have surface tension an order of magnitude higher than water and break up into micro-droplets when mixed with other liquids. In contrast, silicone oil readily mixes into LM foams to create oil-in-LM emulsions with oil inclusions. Previously, the LM was foamed through rapid mixing in air for an extended duration (over 2 hours). This process first results in the internalization of oxide flakes that form at the air-liquid interface. Once a critical fraction of these randomly shaped solid flakes is reached, air bubbles internalize into the LM to create foams that can internalize secondary liquids. Here, we introduce an alternative oil-in-LM emulsion fabrication method that relies on the prior addition of SiO2 micro-particles into the LM before mixing it with the silicone oil. This particle-assisted emulsion formation process provides a higher control over the composition of the LM-particle mixture before oil addition, which we employ to systematically study the impact of particle characteristics and content on the emulsions' composition and properties. We demonstrate that the solid particle size (0.8 µm to 5 µm) and volume fraction (1% to 10%) have a negligible impact on the internalization of the oil inclusions. The inclusions are mostly spherical with diameters of 20 to 100 µm diameter and are internalized by forming new, rather than filling old, geometrical features. We also study the impact of the particle characteristics on the two key properties related to the functional application of the LM emulsions in the thermal management of microelectronics. In particular, we measure the impact of particles and silicone oil on the emulsion's thermal conductivity and its ability to prevent deleterious gallium-induced corrosion and embrittlement of contacting metal substrates.&#xD.

Numerical simulation of heat transfer and entropy generation due to the nanofluid natural convection with viscous dissipation in an inclined square cavity

In this work, the effects of viscous dissipation on heat transfer and entropy generation of the nanofluid natural convection in an inclined square cavity are numerically investigated. A fractional-step semiimplicit finite difference algorithm based on the projection method on a staggered grid is proposed to solve the laminar natural convection problem, which has the advantage of larger time steps. The square cavity is filled with a nanofluid composed of (Cu) copper nanoparticles and water. and the viscous dissipative behavior of the mixture flow is not negligible. The studied parameters are Rayleigh number Ra ( 10 4 and 10 5 ), Eckert number Ec ( 0 − 2 ), the volume fraction of solid particles ϕ ( 0 − 0.06 ), and inclination angle of square cavity α ( 0 − π / 2 ). The Prandtl number is fixed to Pr = 6.2 . The results show that at any inclination angle, the increase in viscous dissipation leads to weakened heat transfer on the hot wall, enhanced heat transfer on the cold wall, and weakened flow in the square cavity. For the base solution without nanoparticles, the Eckert number has the greatest impact, with its effects on the average Nusselt number on the hot wall, maximum streamfunction, and average Nusselt number on the cold wall being ∼13, 0.15, 18.69%, and at Ra = 10 4 , and 12, 0.5, 28.87% at Ra = 10 5 , respectively. Research on entropy generation shows that as Eckert number increases, the entropy generation due to heat transfer increases, while due to fluid friction decreases. As the Rayleigh number increases, the effect of viscous dissipation increases. As the inclination angle increases, the effects of volume fraction and Eckert number weaken. Adding solid particles can effectively weaken the effect of viscous dissipation.

Experimental investigation of particle dynamics in particle-laden turbulent boundary layer

In a horizontal wind tunnel, experiments were performed on both particle-free and particle-laden flows at the same incoming velocity. Glass micro-spheres were carried by air along the turbulent boundary layer at a high Reynolds number (Reτ=3200). The Stokes numbers of the solid particles considered were O(10) and O(102). Under a similar volume fraction, Φv=O(10−5), the velocity and spatial distribution of solid inertial particles were investigated using simultaneous particle image/tracking velocimetry measurements and time-resolved particle imaging. This allowed for the exploration of particle dynamics and their corresponding spatial structure in the particle-laden turbulent boundary layer. The results showed that particle–wall (P-W) interaction occurs in both types of particle-laden flows. However, the particle Stokes number directly affects the intensity of the P-W interaction, significantly altering the behavior and spatial organization of particles. The results from the Voronoi tessellation technique confirmed that preferential clustering still happens for the small particle case. In particular, the premultiplied spectra for the particle concentration showed that the temporal pattern of particle clustering presents a similar time-scale to very large-scale motion (around 22δ, where δ is the boundary layer thickness) in the near-wall region.

Considerations for Ionic Diffusion in Slurry Electrolytes for Redox Flow Batteries

Slurry electrodes have been proposed as a means to enhance the scalability of hybrid redox flow battery (RFB) chemistries for better usability in utility scale energy storage applications1–3. In conventional hybrid RFB’s, scalability is limited due the spatial constraints of the flow cell and the metal deposited by the negative half-reaction on charge1. By using a slurry electrode, the solid metal can be deposited onto electrically conductive particles dispersed in the electrolyte instead of on the stationary electrode within the flow cell. In this way, hybrid RFB chemistries can achieve the same scalability as more commonly studied true RFB chemistries, such as all-vanadium. Due to the high abundance, low cost, and low toxicity of iron electrolytes, the all-iron RFB chemistry is of particular interest for use with a slurry electrode2,4. The usefulness of the slurry electrode depends on the current distribution of the plating reaction. To successfully decouple the storage and power capacities of the RFB and thus enhance its scalability5, the faradaic current of the plating reaction must occur predominantly on the mobile slurry particles, as opposed to on the stationary current collector1. This current distribution is dependent on a variety of factors, such as the applied overpotential, the electrical conductivity of the slurry, the ionic conductivity of the electrolyte, the kinetics of the reaction, and the rate of ionic mass transport to reaction sites. Ionic mass transport in electrolytes containing slurry electrodes may differ from ionic transport in neat electrolyte in interesting and important ways. Due to the volume fraction of the electrolyte occupied by solid particles, the effective concentration of the ionic species may be lower than in neat electrolyte. Further, the solid particle volume fraction hinders ionic diffusion by introducing diffusion path tortuosity. This effect is more severe in higher slurry particle loadings.In this work, the effect of varying dispersed solid particle loading on ionic diffusivity is investigated via voltammetry using a rotating disk electrode. The diffusivities of ionic iron species are measured as a function of the volume fraction of solids dispersed in the electrolyte. Comparisons with the Bruggeman correlation6,7 are made and amendments to the Levich equation are considered.(1) Petek, T. J.; Hoyt, N. C.; Savinell, R. F.; Wainright, J. S. Slurry Electrodes for Iron Plating in an All-Iron Flow Battery. J. Power Sources 2015, 294, 620–626. https://doi.org/10.1016/j.jpowsour.2015.06.050.(2) Petek, T. J. Enhancing the Capacity of All-Iron Flow Batteries: Understanding Crossover and Slurry Electrodes. Ph.D. Thesis 2015, No. May.(3) Narayanan, T. M.; Zhu, Y. G.; Gençer, E.; McKinley, G.; Shao-Horn, Y. Low-Cost Manganese Dioxide Semi-Solid Electrode for Flow Batteries. Joule 2021, 5 (11), 2934–2954. https://doi.org/10.1016/j.joule.2021.07.010.(4) Dinesh, A.; Olivera, S.; Venkatesh, K.; Santosh, M. S.; Priya, M. G.; Inamuddin; Asiri, A. M.; Muralidhara, H. B. Iron-Based Flow Batteries to Store Renewable Energies. Environ. Chem. Lett. 2018, 16 (3), 683–694. https://doi.org/10.1007/s10311-018-0709-8.(5) Weber, A. Z.; Mench, M. M.; Meyers, J. P.; Ross, P. N.; Jeffrey, T.; Liu, Q. Redox Flow Batteries , a Review Environmental Energy Technologies Division , Lawrence Berkeley National Laboratory , Department of Mechanical , Aerospace and Biomedical Engineering , University of Tennessee , Department of Chemical Engineering , McGill Un. 1–72.(6) Tjaden, B.; Cooper, S. J.; Brett, D. J.; Kramer, D.; Shearing, P. R. On the Origin and Application of the Bruggeman Correlation for Analysing Transport Phenomena in Electrochemical Systems. Curr. Opin. Chem. Eng. 2016, 12, 44–51. https://doi.org/10.1016/j.coche.2016.02.006.(7) Chung, D. W.; Ebner, M.; Ely, D. R.; Wood, V.; Edwin García, R. Validity of the Bruggeman Relation for Porous Electrodes. Model. Simul. Mater. Sci. Eng. 2013, 21 (7). https://doi.org/10.1088/0965-0393/21/7/074009.

Influence of Oslo crystallizer structure characteristics on crystallization process

AbstractThe liquid–solid multiphase flow in Oslo crystallizer was simulated by computational fluid dynamics (CFD) and described by Euler–Euler model and k‐ε turbulence model. The velocity field and solid phase concentration field in Oslo crystallizer with different structural elements were systematically studied. The results show that, within the range of 0–82.5°, the fluid velocity and axial mixing in the evaporation chamber are significantly affected by the inlet pipe structure, and the length of the central downcomer also has distinct impact on the crystal classification ability of the crystallizer. As the angle between the axis of the inlet pipe and the tangent line at the inlet point increases, the tangential velocity in the evaporation chamber decreases, the axial velocity near the wall increases, and the volume fraction of solid particles decreases. As the length of the central downcomer increases, the position of the vortex center gradually goes up and moves towards the wall. In order to obtain high‐quality products and extend the continuous operation cycle of the device, the angle between the axis of the inlet pipe and the tangent line at the inlet point should be 60–75°, and the distance between the central downcomer and the bottom of the crystallizer should be .8 m.

Three-Dimensional Analysis of the Thermal Behavior of Alumina-Water Nanofluid Inside Hexagonal and Octagonal Enclosed Domain

The current work focused on the study of the laminar and steady free convection of Aluminum Oxide / Water nanofluid inside cavities. Two different cavities have the same volume but different overall surface area and count of walls are studied. These cavities are heated differentially on the vertical square side walls which of identical area and dimensions for both cavities. The other vertical walls of these cavities have hexagonal and octagonal shapes. The first cavity has eight walls while the second has ten walls. The study accomplished for solid particles volume fraction and Rayleigh number ranges of (φ = 0.01, 0.03, 0.05) and (103 ≤ Ra ≤ 106). The study interested highly by the effect of the cavity geometry parameters including the lateral cross section, the height, the number of walls on the flow and heat transfer. Other flow parameters are recognized on the fluid flow and heat transfer fields like the nanoparticles volume fraction and the Rayleigh number. The results indicated that the surface area increase by means the additional walls has an observed effect on guiding the results. Where the octagonal cavity has better enhancement in heat transfer especially at (Ra=104 and 105). The percent increase in Nu over the hexagonal cavity is (0.6, 0.8, 0.7, 0.3) for the specified Ra range.

Entropy generation in radiative magneto-hydrodynamic mixed convective flow of viscoelastic hybrid nanofluid over a spinning disk

The heat and mass relocation properties of magneto-hydrodynamic mixed convective viscoelastic hybrid nanofluid flow induced by an extending spinning disk under the effect of entropy generation, thermal radiation, convective condition, velocity, and concentration slips has been investigated in this study. For hybrid nanofluid, the amalgamation of aluminum nitride and alumina nanoparticles embedded in carboxymethyl cellulose with a volume mass concentration of 0.0%–0.4% is considered for the study. The acquired system of partial differential equations from the intended problem is translated into ordinary differential equations employing resemblance conversion and solved by the Galerkin finite element approach. The main effects of the governing constraints on the velocity field, temperature dispersion, concentration, Bejan number, entropy production, skin friction, Nusselt number, and Sherwood number were detailed and depicted in graphs and tables. The results show that snowballing in viscoelastic constraint and volume fraction of solid non-sized particles of Al2O3 and AlN can be used to control fluid flow speed. Also, it is observed from the result that an increment in the magnetic field parameter causes a decline in the velocity field. However, the increase in magnetic field constraint and volume fraction of solid non-sized particles of Al2O3 and AlN causes an upsurge in temperature distribution. Entropy generation in the system can also be regulated by using a higher volume fraction of aluminum nitride and alumina nanoparticles. This numerical and theoretical investigation is more useful in bio-viscoelastic fluids, advanced technology, and industry.

Study of the effect of solid particle volume fraction on cavitation characteristics in a centrifugal pump

Study of the effect of solid particle volume fraction on cavitation characteristics in a centrifugal pump

An experimental approach to investigate the viscoelastic and rheological behavior of polydisperse glass suspensions

Polydispersity is an essential factor in characterizing suspensions, specifically in industrial processes. In the present work, we report the viscosity of non-colloidal polydisperse glass suspensions for the first time and study the predictability of log-transformed quadratic viscosity equations over a wide range of blending ratios at a constant total volume fraction of solid particles. The viscosity and viscoelasticity measurement of multimodal suspensions was carried out by mixing three monomodally distributed solid particle suspensions with a relatively narrow size distribution to prepare bidisperse and tridisperse suspensions. The results showed a good agreement between experimental and predicted viscosity data for multimodal suspensions, making the generalized model a good alternative to describe the viscosity of polydisperse mixtures. The diameter ratio of large-to-small particles and the volume fraction of small particles in bidisperse systems strongly affected the viscoelastic behavior of multimodal suspensions. In addition, the dynamic rheology measurement showed that the storage modulus was independent of frequency, while a linear frequency dependence of loss modulus was observed for multimodal suspensions. In the case of polydisperse suspensions, this yield stress and dimensionless elastic modulus increased by declining the particle size ratio and increasing the volume fraction of small particles in bidisperse subsystems.

Influence of unburned pulverized coal on the viscosity of blast furnace slag

ABSTRACT In order to explore the influence of unburned pulverized coal in ironmaking on the viscosity of blast furnace slag, the impact of temperature, volume fraction of solid particles and the rotating speed on the viscosity of CaO–MgO–Al2O3–SiO2 heterogeneous slag were studied by experiment. The calculation model of relative viscosity of heterogeneous slag containing unburned pulverized coal is corrected. The results showed that the viscosity of heterogeneous slag increased with the increase of the volume fraction of the solid particles, and decreased with the increase of the rotating speed. For the heterogeneous slag with the same composition, the relative viscosity is not affected by the temperature and decreases with the increase in the rotating speed. The impact of unburned pulverized coal solid particles on the viscosity of the slag was much larger than the predicted value of the Einstein–Roscoe equation.

CFD modelling of the flow of ice slurry in a vertical slit channel

In this article, the Euler-Euler method was applied to CFD modelling of adiabatic ice slurry flow, for different flow directions in a vertical slit channel. The mean relative accuracy of determining pressure drops compared to experimental studies was 5.6%. Calculations showed that the relative slip velocity and the effect of flow direction on slip velocity increase with decreasing carrier fluid concentration, decreasing mean flow velocity, and decreasing mean solid particles volume fraction. The mean particle slip velocity does not exceed 4%, and local slip velocity values can be 58% of the mean suspended solids flow velocity. For heterogeneous flow, the highest slip velocities occur at a distance of 15% of the channel width from the channel sidewalls. The shape of the solid particles distribution profile is determined by the mean flow velocity and the mean solid particles volume fraction. Excluding the area at a distance of 8% of the channel width from the sidewall where local maximum (for low velocities) and minimum (for higher velocities) values may occur, the profile is stabilised in the central part of the channel. In this study, the boundary curves between heterogeneous and homogeneous flow were determined for ice slurry flow in a vertical slit channel.

Numerical study of geometric parameters effects on the suspended solid particles in the oil transmission pipelines

The innovation of this paper is geometric parameters effects of the oil transmission pipelines on the suspended solid particles. This geometry has been simulated with the Lattice Boltzmann Method based on D2Q9 model for analyzing solid particle tracing, streamlines, solid particle volume fraction, and nondimensional velocity field of fluid flow. These parameters have been investigated in 9 cases of the oil transmission pipelines at two different intensity of fluid flow. The results signified that maximum and minimum ranges of fluid velocity at [Formula: see text] were in case 3 that the oil transmission pipelines with diameter of the pipeline and bending radius, D and 2D, respectively. Also, maximum volume fraction of solid particles at bending radius at [Formula: see text] was in case 3 with diameter of the pipeline and bending radius, D and 2D, respectively. Also, in case 9, solid particles in the oil transmission pipelines were almost symmetrical. Finally, with comparison between figures of solid particles tracing and volume fraction of solid particles, by increasing of the diameter of oil transmission pipelines, the sediment of solid particles was decreased, also, by increasing of the bending radius of oil transmission pipelines, the sediment of solid particles was increased.

Effect of cavitation bubble on the dispersion of magnetorheological polishing fluid under ultrasonic preparation

In the ultrasonic dispersion process, the ultrasonic cavitation effect can seriously affect the dispersion efficiency of magnetorheological polishing fluid (MRPF), but the mechanism remains unclear now. Through considering the continuity equation and Vand viscosity equation of the suspension, a revised cavitation bubble dynamic model in the MRPF was developed and calculated. The effects of presence or absence of solid particles, the volume fraction of solid particles, and viscosity on the cavitation bubble motion characteristics in the MRPF were discussed. Settlement experiments of the MRPF under ultrasonic and mechanical dispersion were observed. Analysis of particle dispersion is made by trinocular biomicroscope and image processing of the microscopic morphology of the MRPF. The results show that the high volume fraction of carbonyl iron particle (CIP) will significantly weaken the cavitation effect, and the low volume fraction of green silicon carbide (GSC) has a negligible effect on the cavitation effect in the MRPF. When the liquid viscosity is greater than or equal to 0.1 Pa·s, it is inconvenient to produce micro-jets in the MRPF. The sedimentation rate of the MRPF prepared by ultrasonic dispersion is lower than mechanical dispersion when the volume fraction of CIP is between 1% and 25%. The dispersion ratio under ultrasonic dispersion is lower than that under mechanical dispersion. The experimental results fit the simulation well. It offers a theoretical basis for exploring the ultrasonic cavitation effect in the industrial application of the MRPF.

Numerical Prediction of Erosion Based on the Solid-Liquid Two-Phase Flow in a Double-Suction Centrifugal Pump

Due to the high sediment content in the Yellow River, the pump units in the pumping stations along the line are often eroded by sediment, causing the reduction of pump efficiency and structural damage. The purpose of this paper is to study the influence of particle diameter on the particle track, erosion distribution and erosion rate in a double-suction centrifugal pump in a pumping station of the Yellow River with a Lagrangian particle-tracking approach and a Tabakoff erosion model. The results show that the surface erosion of the impeller on both sides in the double-suction centrifugal pump has an asymmetric distribution, and the erosion rate on both sides is different. The particle diameter affects the moving trajectory of particles and has a significant effect on the erosion morphology and position in the impeller. With the increase of particle diameter, the velocity of the particles moving towards the pressure side of the blade inlet increases, resulting in punctate impact erosion. When the particle diameter decreases, sliding abrasion gradually forms on the pressure side of the blade outlet. The change rule of the solid particle volume fraction on the impeller wall is consistent with that of erosion distribution on the impeller wall. The larger the solid volume fraction is, the higher the wall erosion rate is.

Jet Impingement Heat Transfer of Confined Single and Double Jets with Non-Newtonian Power Law Nanofluid under the Inclined Magnetic Field Effects for a Partly Curved Heated Wall

Single and double impinging jets heat transfer of non-Newtonian power law nanofluid on a partly curved surface under the inclined magnetic field effects is analyzed with finite element method. The numerical work is performed for various values of Reynolds number (Re, between 100 and 300), Hartmann number (Ha, between 0 and 10), magnetic field inclination (γ, between 0 and 90), curved wall aspect ratio (AR, between 01. and 1.2), power law index (n, between 0.8 and 1.2), nanoparticle volume fraction (ϕ, between 0 and 0.04) and particle size in nm (dp, between 20 and 80). The amount of rise in average Nusselt (Nu) number with Re number depends upon the power law index while the discrepancy between the Newtonian fluid case becomes higher with higher values of power law indices. As compared to case with n = 1, discrepancy in the average Nu number are obtained as −38% and 71.5% for cases with n = 0.8 and n = 1.2. The magnetic field strength and inclination can be used to control the size and number or vortices. As magnetic field is imposed at the higher strength, the average Nu reduces by about 26.6% and 7.5% for single and double jets with n greater than 1 while it increases by about 4.78% and 12.58% with n less than 1. The inclination of magnetic field also plays an important role on the amount of enhancement in the average Nu number for different n values. The aspect ratio of the curved wall affects the flow field slightly while the average Nu variation becomes 5%. Average Nu number increases with higher solid particle volume fraction and with smaller particle size. At the highest particle size, it is increased by about 14%. There is 7% variation in the average Nu number when cases with lowest and highest particle size are compared. Finally, convective heat transfer performance modeling with four inputs and one output is successfully obtained by using Adaptive Neuro-Fuzzy Interface System (ANFIS) which provides fast and accurate prediction results.

Thermal conductivity estimation of nanofluids with TiO2 nanoparticles by employing artificial neural networks

Abstract Applying nanofluids in energy-related technologies and thermal mediums can lead to remarkable enhancement in their efficiency and performance due to their modified thermophysical properties. Among thermophysical properties, thermal conductivity (TC) performs principal role in heat transfer ability of nanofluids. Artificial neural networks (ANNs) have shown promising performance in modeling nanofluids’ TC. In this article, two types of ANNs are used for estimating TC of nanofluids with TiO2 nanoparticles. In this regard, effective factors including particle size, temperature, volume fraction of solid particles and TC of the base fluids are applied at the input of the model. Based on the comparison between the estimated data and the corresponding actual ones, it is concluded that employing multi-layer perceptron (MLP) is superior compared with group method of data handling (GMDH). In the optimal conditions of the networks, the R-squared value of the models based on both MLP and GMDH was 0.999. Moreover, average absolute relative deviations of the mentioned models were around 0.23% and 0.32%, respectively.

Slurry development for lithography-based additive manufacturing of cemented carbide components

This article describes slurry development for lithography-based additive manufacturing (AM) of cemented carbide components. Due to their superior material properties compared to steels, tungsten carbide‑cobalt hardmetals are an exciting material for manufacturing tools. AM technologies' geometric freedom makes it possible to design more efficient tools compared to other manufacturing techniques. These technologies are known as resource-efficient and sustainable processes. The material that is not required for manufacturing is re-used for the production of additional components. The high energy input in laser powder bed-based AM processes leads to strong grain growth and brittle phases, so the achievable mechanical properties are significantly limited. Lithography-based additive manufacturing shows high potential due to the manufacturing of a polymer-bound green body and a subsequent heat treatment. Tungsten carbide‑cobalt (88–12 wt%) slurries were developed with a solid content of 40 vol%, based on the resin's reactive components. Dispersants made it possible to increase the maximum processable volume fraction of solid particles. A thixotropic agent helped stabilize the slurry. Rheological investigations characterized these effects. The influence of the photoinitiator concentration and the volume fraction of tungsten carbide and cobalt particles on the curing depth was analyzed. Prepared slurries and manufactured multi-layered green bodies were evaluated for homogeneity using quantitative microstructure analysis.

Effects of Particle Concentration on the Dynamics of a Single-Channel Sewage Pump under Low-Flow-Rate Conditions

Single-channel sewage pumps are generally used to transport solid-liquid two-phase media consisting of a fluid and solid particles due to the good non-clogging property of such devices. However, the non-axisymmetric structure of the impeller of this type of pumps generally induces flow asymmetry, oscillatory outflow during operations, and hydraulic imbalance. In severe cases, these effects can jeopardize the safety and stability of the overall pump. In the present study, such a problem is investigated in the framework of a Mixture multiphase flow method coupled with a RNG turbulence model used to determine the structure of the flow field and the related motion of transported particles. It is shown that under different inlet particle concentrations, the flow field in the pump exhibits periodic variations of the pressure. The volume fraction of solid particles at the trailing edge of the suction surface of the blade is the largest, and solid particles tend to be concentrated at the outer edge of the pump body. With a rise in import particle content, the pressure and volume fraction of particles in the sewage pump also increase; for a fixed inlet particle concentration, the pressure pulsation amplitude increases with an increase in the flow rate. In addition, under small flow conditions, as the inlet particle concentration increases, the flow field leaving the sewage pump diaphragm near the outlet of the volute becomes more turbulent, and even a secondary back-flow vortex appears.

Marangoni convection of nanofluid in a wavy trapezoidal enclosure

The purpose of this study is to investigate the behaviour of natural convection in a wavy trapezoidal enclosure that is filled with nanofluid. The left wavy wall has wavelength, l, and amplitude, A. The top and bottom walls are adiabatic while the side walls are set to constant temperature, and shear stress occurs at the top of the enclosure. The numerical approach used in this study in order to discretize the governing equations with its boundary conditions is the finite element method where the Galerkin technique is adopted. The solutions obtained are for various values of the Marangoni number, Rayleigh number, and solid particle volume fraction. The graphs of the streamlines, isotherms, local Nusselt, and average Nusselt numbers are then presented and discussed.