Temperature Plots Research Articles

Diagnostic Information Analysis of Quickly Changing Temperature of Exhaust Gas from Marine Diesel Engine Part I Single Factor Analysis

Abstract In this paper, attention was paid to the problem of low controllability of marine medium- and high-speed engines during operation, which significantly limits the parametric diagnosis. The measurement of quickly changing temperature of engine exhaust gas was proposed, the courses of which can be a source of diagnostic information. The F statistic of the Fisher-Snedecor distribution was chosen as a statistical tool. Laboratory tests were carried out on the bench of a Farymann Diesel engine. The tests consisted of introducing the real changes in the constructional structure of the considered functional systems of the engine. Three changed parameters for the structure were reviewed: the active cross-sectional area of the inlet air channel, injector opening pressure and compression ratio. Based on the recorded plots of the quick-changing temperatures of the exhaust gases, three diagnostic measures were defined and subjected to statistical tests. The following data were averaged over one cycle for a 4-stroke piston engine operation, (1) the peak-to-peak value of the exhaust gas temperature, (2) the specific enthalpy of the exhaust gas, and (3) the rate of increase and decrease in the values for the quick-changing exhaust gas temperature. In this paper will present results of the first stage of the elimination study: the one-factor statistical analysis (randomised complete plan). The next part will present the results of the second stage of studies: two-factor analysis (block randomised plan), where the significance of the effect of changing the values of the structure parameters on the diagnostic measures was analysed in the background of a variable engine load.

Mixed convection in a driven cavity with an internal obstacle using the lattice Boltzmann method

The flow and heat transport of a viscous fluid contained in a square cavity have been extensively studied using parametric analysis. Lattice Boltzmann method is used to simulate fluid-flow in a square lid-driven cavity with a square-shaped obstacle in the cavity?s centre. The cavity?s top wall generates flow that moves at a constant speed in its own plane and is maintained at a higher temperature than the bottom wall. Reynolds number, Rayleigh number, Prandtl number, Grashof number, and Richardson number are the primary parameters used in this study. The relevance of natural and forced convection, contributions of conduction, and convection to total heat transfer are estimated. The influence of the temperature of the obstacle on the velocity and temperature of the fluid is also being investigated. When, Ri ? 1, the temperature of the obstacle has almost negligible influence on fluid velocity, the fluids are well mixed, and temperature fluctuations are minor in the bulk of the cavity interior. When, Ri ? 1, the obstacle?s temperature, has a considerable impact on fluid velocity, much of the fluid in the cavity?s middle and bottom regions remains stationary. These regions have a vertically linear temperature distribution. Further studies were carried out to investigate how the Prandtl number influenced the fluid?s temperature. The findings are presented as contour plots of velocity and temperature, streamlines, horizontal and vertical velocity profiles, and vertical temperature profiles.

Impact of Dysprosium doping on the structural and electrical properties of BiSbTe3 single crystals

Breaking of time reversal symmetry in 3D topological insulators and tuning of Fermi level in the vicinity of the Dirac point is a prerequisite for unravelling various exotic physical phenomena which might be leveraged for potential technological device applications. Here we account effective single crystal growth of (BiSb)2-xDyxTe3 where x = 0, 0.005, 0.05 using modified Bridgman method. The structural, morphological, electrical and Hall measurements were performed on the synthesized single crystals. X-ray Diffraction (XRD) measurements confirmed high quality crystal growth with unidirectional orientation of the synthesized crystals. The lattice parameters were found decreasing with Dysprosium (Dy) doping thereby decreasing the lattice volume,indicating the incorporation of Dy atoms in the lattice of BiSbTe3. Scanning Electron Microscopy (SEM) confirmed the layered morphology of synthesized crystals while Energy Dispersive X-ray Spectroscopy (EDX) measurements revealed the uniform distribution of all the elements as well as stoichiometry of prepared crystals. The resistivity versus temperature (ρ-T) plot from 4 K to 300 K showed metallic behaviour of crystals with an increase in resistivity with Dy doping. The Hall resistivity (ρxy) demonstrates that holes are the predominant charge carriers. The Hall data revealed displacement of Fermi level with Dy doping. These results are indicative to the shift in the Fermi level in the vicinity of the Dirac point.

Hydrodynamics and Warmth Trade in Cycles of Cooling of an Attractive Plate in an Attractive Fluid in the Attractive Field

The effect of the magnetic field on heat transfer processes of a magnetized steel plate cooled in a magnetic fluid is experimentally studied. Thermocouples were installed at six points on the surface of the plate along its length. The plots of temperature versus time are obtained in the absence of a magnetic field and in magnetic fields of different intensity. It is found that the intensity of heat exchange depends to a large extent on the magnitude of the magnetic field and on the location of points on the surface of the plate. In a magnetic field, cooling of the central part of the plate occurs with the same intensity as in the absence of a magnetic field and with a lower intensity in comparison with other points on the surface of the plate. Near the plate ends, the cooling rate of the surface is much greater in the magnetic field than in the absence of it. With increasing magnetic field strength, the cooling rate of points in the central part of the plate decreases and is less than in the absence of a magnetic field. The dependence of heat transfer on the magnitude of the magnetic field is explained by the distribution of the magnetic forces acting on the liquid surrounding the plate and the nature of the vapor-air cavities formed near its surface. Experiments on simulation of formation and the shape of vapor-air cavities in a liquid surrounding a magnetizing plate are described.

Heat transfer rates in hot shell, cold tube inclined baffled small shell, and tube heat exchanger using CFD and experimental approach

The work presented is an effort to realize the changes occurring for convective coefficients of heat transfer in STHX fitted with inclined baffles. Effort has been undertaken using Fluent, a commercially available CFD code ona CAD model of small STHX with inclined baffles with cold liquid flowing into the tubes and hot liquid flowing in the shell. Four sets of CFD analysis have been carried out. The hot liquid flow rate through shell compartments varied from 0.2 kg/sec to 0.8 kg/sec in steps of 0.2 kg/sec, while keeping the cold liquid flow condition in tube at 0.4 kg/sec constant. Heat transfer rates, compartment temperatures, and overall heat transfer coefficients, for cold liquid and hot liquid, were studied. The results given by the software using CFD approach were appreciable and comparatively in agreement with the results available by the experimental work, which was undertaken for the same set of inlet pressure conditions, liquid flow rates, and inlet temperatures of liquid for both hot and cold liquids. The experimental output results were also used to validate the results given by the CFD software. The results from the CFD analysis were further used to conclude the effect of baffle inclination on heat duty. The process thus followed also helped realize the effects of baffle inclination on convective heat transfer coefficient of the liquid flow through the shell in an inclined baffle shell and tube heat exchanger. The temperature plots for both cold and hot liquid were also generated for understanding the compartmental temperature distributions inclusive of the inlet and outlet compartments. The heat duty for a heat exchanger has been found to increase with the increase in baffle inclinations from zero degree to 20 degrees. Likewise, the convective heat transfer coefficients have also been found to increase with the increase in baffle inclinations.

The Constant-Stress, Constant-Heating-Rate Test: A Novel Method for Characterizing Transient Mechanical Behavior of Metallic Materials

A novel mechanical test for characterizing the transient, on-heating mechanical behavior of metallic structural materials was developed. It comprises the continuous heating of a specimen at a constant rate while loaded under a constant true stress. Key features of the approach consist of quantifying the thermal expansion (“thermal compliance”) and mechanical compliance of the load train, modeling the plastic flow and onset of localized necking of the test specimen, and the simulation of concurrent phase changes for multi-phase alloys. From such experiments and analyses, the instantaneous, true plastic strain and strain rate as a function of temperature can readily be determined and used to establish constitutive parameters (such as the apparent activation energy, Qapp, for plastic flow) and temperatures at which rapid deformation may occur. The test technique was validated for three alloys, Ti–7Al, Ti–6Al–2Sn–4Zr–2Mo–0.1Si (Ti6242S), and superalloy 718. For the single-phase-α titanium alloy, Ti–7Al, semi-log plots of strain rate vs inverse temperature (ln $$\dot{\varepsilon }$$ vs 1/T) were linear, and yielded a value of Qapp comparable to that for self diffusion of hcp titanium. The corresponding plots for Ti6242S with either a fully equiaxed or duplex (equiaxed/colony α) microstructure were also linear, but exhibited higher values of Qapp, a finding rationalized using simulations of the kinetics of dissolution of equiaxed α as a function of temperature and the so-called “mechanical contribution” to the activation energy of two-phase alloy systems. Last, ln $$\dot{\varepsilon }$$ -vs-1/T plots of 718 were either linear (in the solution-treated condition) or approximately bilinear (in the solution-treated-and-aged condition). These observations were interpreted with the aid of simulations of precipitation and dissolution of γ′′ and γ′ during continuous heating and the retarding effect on straining of a threshold (back) stress associated with the precipitates.

On the mechanisms leading to ordered nanoparticles deposition during single bubble nucleate pool boiling regime

The present study investigates the underlying mechanisms of nanoparticle deposition during nucleate pool boiling on plain hydrophobic surfaces. Single bubble pool boiling experiments with water and two concentrations of SiO2-water nanofluids have been conducted under saturated conditions. Indium tin oxide-coated sapphire has been employed as the substrate surface. Infrared (IR) thermography has been used to map the temperature and heat flux distributions underneath the vapor bubble to identify the mechanisms responsible for imparting an orderly pattern to nanoparticle deposition. Optical characterization of nanoparticle-deposited substrates showed a distinct circular porous structure of the deposited nanoparticles at the nucleation site and almost negligible deposition away from it for both the nanofluid concentrations. Temperature and heat flux contour plots indicated toward the ceasing of microlayers for water-based experiments and existence of microlayers for nanofluids. The observed nature of the nanoparticle deposited layer has been attributed to the prevalent bubble base evaporation mechanism. Interdependence between the bubble base evaporation mechanism and nanoparticle deposition has been discussed. An intriguing feature of the nanoparticle deposited structure in the form of a thin peripheral ring was identified, wherein larger micrometer-sized particles were found to be deposited along the ring while the smaller-sized nanoparticles were found in the inner core region. Plausible explanation(s) for the mechanisms associated with the observed size distribution of nanoparticles over the deposited structure have been provided. The IR thermography-based temperature data have been used for heat transfer partitioning. The analysis showed that the overall heat transfer coefficient decreases with nanofluids as compared to water as the working fluid.

Numerical investigation of glycerol/diesel emulsion combustion in compression ignition conditions using Stochastic Reactor Model

In this work, we numerically investigate the potential of glycerol as a diesel fuel additive to reduce soot emissions. Many different fuel additives offer environmental benefits, since there is a surplus supply of glycerol as a by-product of biodiesel production, it is considered as a promising available candidate. The combustion process of glycerol in a direct injection compression ignition engine has been previously investigated experimentally for a 10 % (vol) glycerol emulsion. Based on the experimental set-up, a zero-dimensional Stochastic Reactor Model (SRM) is constructed to conduct numerical analysis with a detailed chemical mechanism for the combustion of hydrocarbon and oxygenated fuels. Applied models are presented and discussed with a focus on the characteristic mixing time scale of micromixing closure which is calculated using a 0D k-ε. The model constants are optimized to the analysed engine with the aid of a genetic algorithm and the sensitivity analysis is presented. For both fuels, emissions of major species are reproduced well but NOx results are slightly overestimated. Emissions of carbon monoxide are predicted well for the reference diesel fuel, but the SRM does not capture the trend of increased CO with glycerol emulsion. The stochastic nature of the model is used to represent the mixture inhomogeneity, and the results are analysed using equivalence ratio–temperature plots to identify soot promoting conditions. The evolution of selected soot precursor and oxidizers is analysed, showing the capability of glycerol to reduce the former and increase the latter with a moderate effect. Soot formation and decomposition rates are presented, with very similar behaviour for both fuels. A shorter combustion phasing for the glycerol emulsion was observed and identified as the main contributory factor that led to the soot reduction while the chemical effect i.e oxygen content of the glycerol was present but not the dominant factor. The soot model results do not provide any evidence for the origin of experimentally observed small-sized particles, but it is discussed that the emissions results indicate the presence of low volatile compounds that could condense in the exhaust system.

Large eddy simulation of a supersonic lifted hydrogen flame with sparse-Lagrangian multiple mapping conditioning approach

The Multiple Mapping Conditioning / Large Eddy Simulation (MMC-LES) approach is used to simulate a supersonic lifted hydrogen jet flame, which features shock-induced autoignition, shock-flame interaction, lifted flame stabilization, and finite-rate chemistry effects. The shocks and expansion waves, shock-reaction interactions and overall flame characteristics are accurately reproduced by the model. Predictions are compared with the detailed experimental data for the mean axial velocity, mean and root-mean-square temperature, species mole fractions, and mixture fraction at various locations. The predicted and experimentally observed flame structures are compared through scatter plots of species mole fractions and temperature against mixture fraction. Unlike most past MMC-LES which has been applied to low-Mach flames, in this supersonic flame case pressure work and viscous heating are included in the stochastic FDF equations. Analysis indicates that the pressure work plays an important role in autoignition induction and flame stabilization, whereas viscous heating is only significant in shear layers (but still negligibly small compared to the pressure work). The evolutions of particle information subject to local gas dynamics are extracted through trajectory analysis on representative fuel and oxidizer particles. The particles intermittently enter the extinction region and may be deviated from the full burning or mixing lines under the effects of shocks, expansion waves and viscous heating. The chemical explosive mode analysis performed on the Lagrangian particles shows that temperature, the H and OH radicals contribute dominantly to CEM respectively in the central fuel jet, fuel-rich and fuel-lean sides. The pronounced particle Damköhler numbers first occur in the fuel jet / coflow shear layer, enhanced at the first shock intersection point and peak around the flame stabilization point.

Advanced method for structure-strength-ductility assessment of dispersion-strengthened FCC metals using activation work, mean slip distance and constitutive relation analyses: Decoding the Haasen plot

The role of cross-slip activation on controlling dislocation mechanisms and deformation debris creation in a dispersion-strengthened matrix (DSM) face-centred cubic metal, GlidCop®, has been elucidated using experimental measurement of the strain rate sensitivity, S, the mean slip distance, λ, and constitutive relation analyses (CRA) from 78 to 473 K. If the stress for cross-slip activation is larger than that of DSM yield stress, geometrically necessary prismatic loops (GNPL) are generated, but the rate controlling kinetics is that of vacancy-drag for cube-textured copper wire-specimens. With increasing temperature, percolation continues to occur by Orowan looping. However, upon yielding, GNPL formation is replaced by various types of dipole loop creation due to dislocation intersections from multiple slip. Loops that convert to stacking fault tetrahedra are measurable, but opposite sign dipoles are dynamically annihilated by pipe diffusion reducing debris retention. The rate controlling mechanisms are identified in the temperature range in which S is constant and the activation energy to overcome the obstacle becomes identical to the measurable activation work. This study shows that cross-slip activation stress determined by CRA, when superposed on the yield stress versus temperature plot of DSM alloys, can identify the mechanism-change temperatures. Subsequent S versus temperature profiles, determined from a new method of Haasen plot analysis of up- and down-strain-rate change tests, can delineate the prime rate-controlling mechanisms, characterize the stored debris and determine whether non-shearing or shearing of particles had occurred. Hence, an advanced method to characterize plastic behavior of DSM alloys has been developed.

Time-Variant Nonparametric Extreme Quantile Estimation with Application to Us Temperature Data

Statistical modelling for several years of daily temperature data is somewhat challenging due to remarkable variations of negative and positive temperatures throughout the year. A scatter plot of day and daily temperature shows the high magnitude of variations among data points as dots fall only in the first and fourth quadrants. One parametric modelling approach to this data is to use quantile regression to obtain regression lines on different quantiles. However, these quantile lines cannot make reliable predictions on extreme quantiles when time-variant quantiles differ significantly. In this paper, we develop several two-step nonparametric smoothing estimators and show their superiority over quantile regression for smoothing estimation of nonparametric quantiles with a novel application to temperature data. Narrower bootstrap confidence bands, smaller Minimum Absolute Distance (MAD), smaller bias and MSE, and higher coverage from the application and simulation results show that smoothing curves obtained from these smoothing estimators outperform the quantile regression line.

Bejan's flow visualization of buoyancy-driven flow of a hydromagnetic Casson fluid from an isothermal wavy surface

The proposed work numerically investigates the buoyancy-driven flow of Casson fluid from a vertical wavy surface under the influence of a magnetic field and evaluates the underlying transport of heat in the free convective regime both quantitatively and qualitatively. Pertaining to this analysis, the primitive forms of coupled non-linear partial differential equations are evaluated with the help of an efficient and straightforward Crank–Nicolson implicit finite difference technique. By representing the graphical plots of flow velocity, temperature, and friction-factor coefficients, obtained for different physical parametric values pertinent to this analysis, we discuss the influence of the Hartmann number, surface waviness parameter, and rheological parameter of the fluid on the underlying thermohydrodynamics. In addition to the isotherm and streamline plots, by demonstrating the functional form, we discuss an extensive flow visualization technique that provides unique heat flow visualization for the wavy surface based on Bejan's heat function concept. The results indicate that for increasing the magnitude of the magnetic parameter, the evolution of isotherms, streamlines, and heatlines deviates periodically with a higher amplitude, which signifies the transfer of high heat energy as well as the efficient transport of heat in the convective regime.

Climate Change Dynamics versus Human Biodiversity Responses in a Rainfall Upland Area

The study has explored statistical and time series techniques that are used in the analysis of the data on conditional and specified activities of the atmosphere, ambient and sensible activities in Ado Ekiti, South West Nigeria. The plots of the atmospheric-ambient temperatures against sequential time series reveals an uneven pattern in temperature exponents or changes over the period covered, with behavioral trends with high relative wind speed resulting in most precipitations. It is visualized from the results that the ambient indices are with deviance of about compared to atmospheric data. Observations also shown from our comparisons that with atmospheric temperatures at about , saturated cloud resulting in precipitations were visible. Results show that, minus the tropical average atmospheric temperature which is , maximum temperature determining features for precipitations are about and in May and June respectively, prevalent for specified days under study. Rarely on clear air days with about , possible precipitation was stratified or widespread when maximum temperature reaching about and justifying human biodiversity activities in the area of study.

Impact of Gd substitution on the structure, hyperfine interactions, and magnetic properties of Sr hexaferrites

Gd3+-substituted nano-sized Sr-hexaferrite, SrGdxFe12-xO19 (0.00 ≤ x ≤ 0.05) NHFs (SrGd NHFs), were fabricated by a one-pot sol-gel combustion approach assisted by citric acid. The crystal structures, surface morphologies, magnetic properties, and hyperfine interactions of the calcined samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDX), high-resolution TEM (HR-TEM), vibrating sample magnetometry (VSM), and Mössbauer spectrometry. The oxidation states and chemical compositions of the NHFs were evaluated using XPS. The single-phase crystalline structures of all products were confirmed by XRD analysis. The average crystallite sizes determined from the peaks of the highest intensity using the Scherrer equation were between 38 and 50 nm. Using 57Fe Mössbauer spectroscopy data, the quadrupole splitting, hyperfine magnetic field, isomer shift, and line width variation of the products were determined. The Mössbauer spectra showed that octahedral (Oh) 12k and 2a sites were preferentially occupied by Gd3+ions. The Gd3+content was found to have no influence on the electron density around the Fe3+ions at any crystallographic site. The magnetization (M) versus magnetic field (H) data were collected at room (300 K) and ultra-low (10 K) temperatures. Neither the zero-field cooling (ZFC) nor field cooling (FC) mode plots of magnetization vs. temperature revealed any blocking temperature peaks. Both the M-H curves and FC-ZFC magnetization revealed ferrimagnetic behavior of the products. Furthermore, the FC-ZFC magnetization exhibited super-spin glass behavior at low temperatures. Reductions in the coercive field (Hc), saturation magnetization (Ms), and remanence (Mr) magnetization were achieved with Gd substitution of up to 0.03 into the hexaferrite system; however, with further increase in Gd content, these values started to increase. The calculated squareness ratio (Mr/Ms) revealed that all of the NHF samples were composed of single magnetic domain particles with uniaxial anisotropy.

Plant functional types regulate non‐additive responses of soil respiration to 5‐year warming and nitrogen addition in a semi‐arid grassland

Abstract How climate warming interacts with atmospheric nitrogen (N) deposition to affect carbon (C) release from soils remains largely elusive, posing a major challenge in projecting climate change‒terrestrial C feedback. As part of a 5‐year (2006–2010) field manipulative experiment, this study was designed to examine the effects of 24‐hr continuous warming and N addition on soil respiration and explore the underlying mechanisms in a semi‐arid grassland on the Mongolian Plateau, China. Across the 5 years and all plots, soil respiration was not changed under the continuous warming, but was decreased by 3.7% under the N addition. The suppression of soil respiration by N addition in the third year and later could be mainly due to the reductions in the forb‐to‐grass biomass ratios. Moreover, there were interactive effects between continuous warming and N addition on soil respiration. Continuous warming increased soil respiration by 5.8% in the ambient N plots, but reduced it by 6.3% in the enriched N plots. Soil respiration was unaffected by N addition in the ambient temperature plots yet decreased by 9.4% in the elevated temperature plots. Changes of soil moisture and the proportion of legume biomass in the community might be primarily responsible for the non‐additive effects of continuous warming and N addition on soil respiration. This study provides empirical evidence for the positive climate warming‒soil C feedback in the ambient N condition. However, N deposition reverses the positive warming‒soil C feedback into a negative feedback, leading to decreased C loss from soils under a warming climate. Incorporating our findings into C‐cycling models could reduce the uncertainties of model projections for land C sink and global C cycling under multifactorial global change scenarios. A free Plain Language Summary can be found within the Supporting Information of this article.

Conjugate natural convection in a vertically divided square enclosure by a corrugated solid partition into air and water regions

The purpose of this study is to investigate conjugate natural convection inside a partitioned differentially heated square enclosure. A corrugated heat-conducting solid partition of three different values of thickness and three different materials is selected. The partition divides the empty spaces of the enclosure into two fluid zones and those zones are filled with air and water, respectively. The governing Navier-Stokes and energy equations are numerically solved by means of the finite element method. The effects of corrugation amplitude, corrugation frequency, thermal conductivity, position and thickness of the corrugated solid partition along with the variation of Rayleigh numbers based on the properties of air on thermal and flow fields have been depicted through contour plots of temperature and stream function, respectively. The average Nusselt number along the hot wall and the average temperatures of both air and water in their respective domains have also been examined to observe the influence of the above variations. The change of corrugation amplitude, thermal conductivity, position and thickness of the corrugated solid partition has considerable effects on heat transfer performance with increasing Rayleigh number. Out of those controlling parameters, it is found that increasing partition thermal conductivity enhances thermal performance by up to 25%. However, the variation of corrugation frequency of the partition as a function of Rayleigh number does not seem to be significant for heat transfer enhancement.

A class of second‐order schemes with application to chemically reactive radiative natural convection flow in a rectangular enclosure

AbstractA new class of explicit second‐order schemes is proposed for solving time‐dependent partial differential equations. This class of proposed schemes is constructed on three‐time levels. Stability is found for the scalar two‐dimensional heat equation and the system of time‐dependent partial differential equations. This partial differential equations system comprises a non‐dimensional set of equations obtained from the governing equations of natural convection chemically reactive fluid flow in a rectangular enclosure with thermal radiations. Flow is generated by applying the force of pressure. Graphs of streamlines, contours plots of velocity, temperature and concentration profiles, local Nusselt number, and local Sherwood number are displayed with the variation of time and parameters in the considered partial differential equations. Results are shown in the form of streamlines and contour plots. It is found that local Nusselt number has dual behavior by enhancing radiation parameter whereas local Sherwood number de‐escalates by upraising the reaction rate parameter. It is hoped that the results in this pagination will serve as a valuable resource for future fluid‐flow studies in an enclosed industrial environment.

Heat transportation enrichment and elliptic cylindrical solution of time-dependent flow

The main focus of this article is to examine the effects of heat transfer for a compressible time-dependent laminar flow pass the two distinctly positioned elliptic cylinders. The Mac number is chosen below 0.3 to keep the flow laminar. The heat transfer feature has been added and coupled with the laminar flow. The heat transfer feature adjusted for constant pressure. The arising Naiver-Stokes equations have been addressed numerically. The mesh has also been created and its entities have been elaborated statistically. The outcomes of velocity distribution, pressure distribution, 2D temperature plots, isothermal contours, drag coefficient, streamlines, and surface volume of fluid are discussed. The BDF technique has been employed to tackle the problem numerically. It was observed that the velocity profile at the boundaries of the elliptic cylinder has a maximum value, 3.85 m/s. The pressure distribution is observed maximum around elliptic cylinders. The heat transfer coefficient has maximum values at the upper and lower boundaries, the maximum temperature value observed is 290K. The isothermal contours, streamlines, and velocity volume were also studied. The drag coefficient is observed increasing but the drag force is decreasing. The mathematical modeling of the current problem has been designed in COMSOL.

Numerical simulation for heat and mass transport analysis for magnetic-nanofluids flow through stretchable convergent/divergent channels

This paper adopts a theoretical approach to explore the heat and mass transport features for MHD Jeffery–Hamel flow of viscous nanofluids through convergent/divergent channels with stretching or shrinking walls. Recently, this type of flows generated by nonparallel inclined plates with converging or diverging properties has been frequently utilized in various industrial and engineering processes, like, blood flow through arteries, different cavity flows and flow through canals. The current flow model is formulated mathematically in terms of partial differential equations (PDEs) in accordance with conservation laws under an assumption that the flow is symmetric and purely radial. In addition, heat and mass transport mechanisms are being modeled in the presence of Brownian motion and thermophoretic aspects using Buongiorno’s nanofluid model. The dimensionless variables are employed to get the non-dimensional forms of the governing PDEs. The built-in MATLAB routine bvpc4 is implemented to determine the numerical solutions for governing the nonlinear system of ordinary differential equations (ODEs). Numerical results are presented in the form of velocity, temperature and concentration plots to visualize the influence of active flow parameters. The simulated results revealed that the Reynold number has an opposite effect on dimensionless velocity profiles in the case of convergent and divergent channels. Besides, the temperature distributions enhance for higher values of Brownian motion parameter.

Heat transfer intensification of nanomaterial with involve of swirl flow device concerning entropy generation

The thermal features of hybrid nano-powder turbulent motion through a pipe employing helical turbulator is numerically simulated via Finite Volume Method (FVM). The hybrid nanofluid (MWCNTs + Fe3O4 + H2O) is obtained by uniformly dispersing MWCNTs + Fe3O4 nanomaterials in H2O. The characteristics features of thermal energy transfer of hybrid nanofluid are investigated by varying the pitch ratio (P) of the helical turbulator and Reynolds number (Re) of the fluid. The outputs of the study are depicted in terms of contour plots of temperature, velocity, frictional irreversibility Sgen,f, and thermal irreversibility Sgen,th. The variation of Sgen,f, and Sgen,th with changing P and Re are also displayed by 3D plots. It is found that making the fluid more turbulent by increasing Re, the temperature of the fluid drops whereas the fluid velocity augments. The frictional irreversibility enhances, whereas the thermal irreversibility drops with the increasing turbulent motion. The decreasing P causes to drop the temperature of the higher turbulent fluid flow, while opposite effect is observed for smaller Re. The decreasing P causes to enhance the fluid mixing and thus augments the fluid velocity. Sgen,f and Sgen,th both augment with decreasing P. The comparison of current outputs with the older article shows an acceptable accuracy. The results of the present investigation will be useful in modelling of efficient thermal energy transfer systems.