Increase In Nusselt Number Research Articles

Convection heat transfer of MHD fluid flow in the circular cavity with various obstacles: Finite element approach

In the present research, a study has been conducted on a model to investigate magnetohydrodynamic (MHD) heat and mass transfer phenomena. In the geometry of this model, there is a circular cavity with a variable number of obstacles in each step. At each stage, some obstacles are heated, and its effect on fluid flow and heat transfer is investigated. Solving and developing partial differential equations is done using the finite element method. The effects of Rayleigh and Hartmann numbers on flow lines, isotherms, and equivalent concentrations have been investigated, and the output was displayed as contours and graphs. Finally, the Nusselt diagram is displayed. The main purpose of the present study is to evaluate the effect of changes in Rayleigh and Hartmann numbers in different geometries on its behavior. This particular flow configuration was chosen because of the fundamental role of magnetohydrodynamics and its widespread use in engineering, industry, and medicine. The findings of this research show that in almost all investigated geometries, the behavior of streamlines, isotherms, and isothermal concentrations is anti-symmetrical at X = 0.5. Also, with the heating of the upper obstacles, the total Nusselt number decreases, and with the heating of the lower obstacles, the total Nusselt number increases. The behavior of the total Nusselt number against the increase of the thermal radiation parameter is increasing, and as the number of obstacles inside the cavity increases, the total Nusselt number increases.

Conceptual design of narrow annular channel heater with rectangular wire coil for the simulator of solid-fuel thorium molten salt reactor

To heat the simulator core of a solid-fuel thorium molten salt reactor, the narrow annular channel heater with rectangular wire coil separating from the tube wall is proposed. Three-dimensional numerical models are developed, and the simulated result shows that negative axial, radial and tangential velocities in the enhanced narrow annular channel heater are generated compared to the smooth narrow annular channel heater. As the wire width increases and helical pitch decreases, the Nusselt number and friction factor increase. The maximum Nusselt number for enhanced narrow annular channel heater is 5.6 times that for smooth narrow annular channel heater. The overall performance of enhanced narrow annular channel heater is evaluated at a constant pumping power, the value of which is in the range of 1.21–1.85. The best enhanced narrow annular channel heater for the simulator of solid-fuel thorium molten salt reactor is determined based on the overall performance. The maximum outer wall and fluid temperatures of enhanced narrow annular channel heater for the simulator of solid-fuel thorium molten salt reactor are 937.94 K and 931.01 K, which are within the safety limit values of 1143.15 K and 977.15 K, respectively. This design will provide a new method to heat molten salt.

Examining the effect of backward/forward-facing wavy channels on the thermohydraulic performance of a printed circuit heat exchanger under the laminar flow regime

The printed circuit heat exchanger (PCHE) has been used in many important engineering applications because of its advantages, including its small size and high efficiency. This study aims to enhance the thermohydraulic characteristics of the PCHE by using new channels characterised by a three-dimensional flow path. These proposed backward/forward-facing wavy channels (BFFWCs) are a combination of a wave path in the horizontal plane and a U-shape path in the vertical plane. Under laminar water flow on both sides of the PCHE, a numerical study was conducted to assess the thermohydraulic characteristics of the proposed PCHEs with various wave amplitudes for channels and angles of attack for six models of BFFWCs on the basis of the conventional PCHE. The evaluation parameters that were adopted are the Nusselt number, friction factor, thermohydraulic performance criterion, and PCHE's effectiveness. Two models of the PCHE were manufactured and tested—one for the straight channels and the other for the proposed channels—to verify the accuracy of the numerical simulation results by comparing them with the experimental outcomes. Results indicated that the three-dimensional flow path has a positive influence on enhancing the heat transfer rate of the exchanger, with a slight increase in the pressure loss. The Nusselt number and friction factor increase with increasing wave amplitude and angle of attack. Compared with conventional PCHE, the maximum improvement in the Nusselt number is as much as 71 % and 78 % for model 3 (amplitude = 0.8 and angle of attack = 30°) and model 6 (amplitude = 0.8 and angle of attack = 60°). The thermohydraulic performance of model 3 was better than that of model 6. The maximum obtained thermohydraulic performance criterion reaches about 1.43 and 1.40 for models 3 and 6, respectively.

Integration of a Gas Model Into CFD Analysis for the Simulation of Turbine Exhaust Flows with High Steam Loads

Abstract The Water-Enhanced Turbofan (WET) is a promising future propulsion concept to reduce aero engine emissions. In the WETengine, a heat exchanger uses turbine exhaust heat in order to generate superheated steam out of liquid water. For evaporator design, CFD simulations are necessary since correlation-based predictions have a high uncertainty during preliminary design. A common way of modeling steam loaded flows is the integration of gas models into CFD analysis. However, to the author's knowledge, there is no gas model published that accounts for the exact gas composition of turbine exhaust flows with high steam loads and is commonly used by low- and high-fidelity methods. Therefore, a gas model predicting the thermodynamic behavior of the turbine exhaust flow considering high steam loads is presented and integrated into an existing CFD solver. The approach is able to incorporate the implemented gas model into the CFD simulation by two methods: runtime and offline. The offline method has a computational advantage in iteration time compared to the runtime integration. As demonstration case, a single two dimensional cylinder is considered. A variation of the steam loading of the flow shows a significant effect on local properties and therefore on local and average heat transfer. Increasing the steam loading up to 40 % results in an increase of the average Nusselt number of 17 %.

Comparison study on thermo-hydraulic performance of circular and airfoil shaped wire-wrapped rod bundle

The turbulent flow behavior and heat transfer performance of wire-wrapped rod bundles have a significant impact on the thermal–hydraulic characteristics and safety of Generation IV nuclear reactors. In this study, the airfoil-shaped wire-wrapped bundle is proposed to improve the comprehensive performance of advanced reactor cores, and the thermal–hydraulic performance has been compared with the circular-shaped wire-wrapped bundle. Special attention has been paid to the temperature variation and friction pressure loss caused by the wire wraps. Specifically, the generation of the secondary flow is the main factor. The airfoil-shaped wire-wrapped bundle exhibits a half friction pressure loss, a more uniformed temperature distribution, and a reduction of the hot spot temperature compared to the circular-shaped wire-wrapped bundle. Moreover, the airfoil-shaped wire shows a 16.3% increase in Nusselt number and a 2.0% increase in friction factor compared to circular-shaped wire, resulting in an 8.7% increase in performance evaluation criteria (PEC). The airfoil-shaped wire-wrapped bundle demonstrates better comprehensive performance than the circular-shaped wire-wrapped bundle in terms of PEC.

Significance role of dual porosity and interfacial nanolayer mechanisms on hybrid nanofluids flow: A symmetry flow model

The investigation of heat and mass transfer between two porous disks containing porous media is the focus of this paper. In this research, (Ag–Al2O3/water)-based hybrid nanofluid is used. Governing partial differential equations are converted to nonlinear ordinary differential equations by similarity transformations. Numerical solutions to nonlinear systems of equations are achieved using the shooting technique. It is examined how the particle’s diameter and nanolayer thickness affect the thermal conductivity of a hybrid nanofluid. Due to the increment of nanolayer thickness, the Nusselt number increases and vice versa for the radius of the particle. Tables and graphs show how the governing parameters influence velocity, temperature, and mass concentration profiles, as well as physical quantities such as skin friction coefficient and Nusselt number. As the values of the porous medium parameters ([Formula: see text]–13) and nanolayer thickness ([Formula: see text]–12) elevate, the flow of skin friction coefficient and Nusselt number escalate in both porous disks. Moreover, as the values of the particle radius ([Formula: see text]% to 12%) and Reynolds number ([Formula: see text]1 to 2) amplify, the flow of heat transfer rate is diminished in the lower disk. Porous materials have a high surface area, which increases the contact area between the nanofluids and the porous medium. Porous materials can enhance the permeability of the fluid, reducing the pressure drop in the system. This can be advantageous in applications where high flow rates and low-pressure drops are desired, such as in heat exchangers or cooling systems. Porous materials can provide trapping sites or adhesion points for the nanoparticles, enhancing their dispersion and stability within the hybrid nanofluids. The porosity of the flow medium can therefore influence the purification and filtration efficiency of the hybrid nanofluids, ensuring their cleanliness and functionality. Understanding and controlling the porosity can help optimize the flow characteristics of the nanofluids in various applications. Overall this field will focus on refining hybrid nanofluid compositions, improving modeling techniques, validating experimental findings, optimizing system designs, and exploring new applications.

Experimental and CFD-DEM study on local packing distribution and thermofluidic analysis of binary packed bed

In recent years, binary-packed beds have drawn attention due to their higher packing density and greater heat extraction capacity than mono-sized packed beds. In the past, the research on binary-packed beds mainly focused on finding empirical correlations for hydraulic permeability and equivalent thermal conductivity. Studies on fluid flow and heat transfer characterisation of the packed bed filled with binary particles are relatively scarce. In this work, the fluid flow and heat transfer analysis of purge gas flowing through the binary packed bed (1 ≤ size ratio ≤ 7 and at a volume of large particles = 40 %) is investigated using non-destructive experimental and Computational fluid dynamics-Discrete element modelling (CFD-DEM) approaches. An empirical correlation is developed for the local packing distribution inside binary packed beds. Based on the CFD-DEM results, the Ergun equation is modified to present the analytical equation for calculating the pressure drop for binary-packed beds at lower and higher Reynolds numbers. Further, the effect of the different size ratios on the fluid flow and heat transfer behaviour of the purge gas for binary-packed beds is investigated. The local packing factor increases with increasing the size ratio since small particles occupy the void among the large particles. This effect also increases the region with zero or negative flow at a higher size ratio. It is found that the purge gas penetrates deeper with an increasing size ratio; therefore, the heat extraction behaviour and the Nusselt number increase with increasing size ratios.

Etude numérique de l’effet des générateurs de vortex longitudinaux sur le transfert thermique d’un écoulement laminaire traversant un micro-canal

We conducted, in this work, a three-dimensional numerical study of forced convection heat transfer of a laminar flow of water passing through micro-channels with and without longitudinal vortex generator, using the CFD code “Ansys- Fluent”. This work aimed to elucidate the effect of vortex generators on the dynamic and thermal behavior of the micro-fluidic flow. The results obtained show that the increase in the Reynolds number leads to an improvement in the quality of heat transfer in both cases of the study. Rectangular micro-channel with LVG can improve heat transfer compared to smooth rectangular micro-channel while consuming more pressure drop. In the range of Reynolds numbers between 200 and 1200, a 2-21% increase in the mean Nusselt number was observed for micro-channels with LVG compared to smooth micro-channels. This occurs through better mixing of the fluid, reduction in the thickness of the thermal boundary layer, and increased heat transfer area. In addition, the friction factor has been increased by more than 50% compared to smooth micro-channels, due to the local resistance of LVGs and the presence of secondary flows.

Radiative Jeffrey fluid transport over a stretching surface with anomalous heat and mass flux

As a means of influencing technological advancements in engineering applications and various fluid products, the generalized Fourier’s and Fick’s models have proven to be of great importance. Industries such as power station engineering, high thermal material processing, and bio-heat elements apply the concept of anomalous heat and mass transfer mechanism. The objective of this study is to stimulate the flow of a radiative magnetohydrodynamics Jeffery fluid over an expanding surface with anomalous heat and mass transfer dynamics subjected to nth order reaction and variable thermophysical properties. A set of similarity transformations is used to neutralize the governing equations into a nondimensionless form. To obtain the model parametric analysis, a numerical tool via the spectral local linearization method (SLLM) is deployed after transformation of the governing flow equation from a two-unknown partial differential equations to a one-variable ordinary differential equation. It is observed that the thermal boundary layer thickness is found to be enhanced with increasing parametric values of magnetic, Eckert and radiation parameters. For the radiation parameter [Formula: see text], the skin drag force, Nusselt and Sherwood number increase by [Formula: see text], [Formula: see text] and [Formula: see text], respectively. Additionally, a [Formula: see text] increment in the nth order parameter boosts the rate of heat transfer by [Formula: see text] while it downsizes the Sherwood number by [Formula: see text].

Effect of diameter, twist angle, and blade count on the thermal-hydraulic performance of a decaying twisted swirler

Inserting a decaying swirler into a heat exchanger has been shown to improve heat transfer with minimal effect on the friction factor. The study analyses the effect of diameter, twist angle, and blade count on the thermal-hydraulic performance of a Decaying Twisted Swirler (DTS) in a horizontally heated tube. The diameter, twist angle, and DTS's blade count are examined for 13.5 mm–15.5 mm with a 0.5 mm interval, 0°–360° with a 60° gap, and 2 to 6 blades, respectively. The Nusselt number, friction factor, and thermal-hydraulic performance are examined for Reynolds numbers between 4583 and 35000. The relative Nusselt number and friction factor increase as DTS diameter and twist angle increase, reaching a maximum value at Re = 4583. Despite this, the relative Nusselt number dispersed as the blade count increased. The relative friction factor increases as the blade count increases. Maximum relative Nusselt number and friction factor reached 1.64 and 3.25, respectively with DTS's 15.5 mm diameter, 360° angle, and 4 blades. Nonetheless, the thermal-hydraulic performance is greatest when the DTS has a diameter of 15.5 mm, a twist angle of 180°, and 2 blades with 1.17.

Central composite design (CCD)-Response surface methodology (RSM) for modeling and simulation of MWCNT-water nanofluid inside hexagonal cavity: Application to electronic cooling

PurposeIn application of hexagonal shapes, engineers and researchers use mathematical modeling, computational fluid dynamics (CFD), and experimental techniques to study natural convection inside hexagonal cavities and improve the design and efficiency of engineering systems. The exploration of fluid performance in hexagonal cavity has been an important problem from the earlier in the fluid mechanics field. The present transient study about thermal reaction and behavior of natural convectional MWCNT-water nanofluid flow privileged a hexagonal cavity in the occurrence of magnetic field is scrutinized. The flow domain of hexagonal structure cavity is a partitioned with lower heated cavity wall and inner four blocks are also heated. The upper wall of the cavity is considered insulated. Furthermore the other remaining walls of the hexagonal cavity are cold. ApproachThe two-dimensional steady, incompressible, governing equations which involve continuity, velocity, and temperature equations of mono nanofluid in a dimensionless form are expressed in vertically and horizontal directions respectively. Moreover, transformed the governing equations into their dimensionless system then elucidated numerically with the help of Galerkin Finite Element Method. Furthermore response surface methodology (RSM) has been utilized to obtaining the optimal values of the designed parameters. This combined process was successfully sculpted and optimized utilized a central composite design with response surface methodology. FindingsThe numerical fallouts of the flow controlling parameters scrutinized containing streamlines, velocities components and isotherms are elaborated. The investigation depicts enhanced convection velocity and temperature outcomes for different values of Rayleigh number. The average Nusselt number is drops as Rayleigh number boosts up. It is concluded that the Nusselt number is reduces for Hartmann number. For larger nanoparticles fraction Nusselt number increases. LimitationsThis analysis has particular scope for improvement. In additions, studies can be showed on the improvement of hexagonal cavity walls designs, thickness, and size of the walls of enclosure cavity. Furthermore the heated blocks are involved inside the cavity. Practical applicationThe natural convection flow through hexagonal cavity reveals major importance and those geometrical shapes are playing major role in electronic cooling. In electronics, hexagonal cavities can be found in heat sinks and electronic packages. Natural convection plays a crucial role in dissipating heat from electronic devices, such as microprocessors, power electronics, and LED lighting systems. Nanofluids exhibit potential heat transfer as compared to conventional coolants. With this aim, the current analysis enlightens the natural convection flow of MWCNTs-water nanofluid inside hexagonal cavity and square-shaped blocks. OriginalityThis analysis is original, and no previous investigation has been accompanied considering the enclosure domain of cavity and variation of the walls number.

Heat transfer study of natural circulation serpentine-shaped loops

Wide range of industrial applications have been utilized natural circulation loops due to heat transport achieved without the aid of any fluid-moving machinery. Moreover, it has been commonly used either two-phase-rectangular- or square-shaped loops owing these geometries promote satisfactory heat transfer and buoyancy forces performance, however, these two geometries require structural elements of considerable size for certain applications. Therefore, this study thoroughly examined a novel design of 10- and 14-elbow-single-phase-serpentine-shaped loops set in vertical configuration for improving cold water dispensers’ systems in a so called side-by-side refrigerator with the size restriction of its cabinet dimensions. Furthermore, when the application was not constricted to the use of water, numerical tests of heat transfer analysis for three working fluids commonly employed in industrial processes, namely, ethylene glycol, ethanol, and air, also was done. Both loops had the same surface area exposed to the heat source and heat sink, along with the total volume within the loops and the pipeline diameter were equal in the two cases. From the procured results, on one hand, when water was used and Reynolds number was increasing, employing the 10-elbow loop, an increase in internal Nusselt number of 24.5% was obtained. On the other hand, when ethanol was used an increase of Nusselt number of 27.28% was achieved. Finally, a great influence of the height of the loop on the increase of buoyancy forces was observed, hence, higher values for Rayleigh number were obtained when 14-elbow loop was utilized instead of 10-elbow loop; nonetheless, higher values of Rayleigh number did not result in greater values of Nusselt number, concluding that a smaller number of elbows promoted a better heat transfer performance under the operation conditions of the present work.

A novel method to improve the performance of PCM thermal energy storage units using a small oscillator plate-numerical analysis

Employing a small oscillator plate is proposed as a novel idea to improve the performance of phase change material (PCM) based thermal energy storage unit. This idea could make mixing heat flow toward the PCM solid-liquid interface to hasten the melting and heat transfer rates. Opposite to the vibration of the whole PCM heat sink suggested in the literature, it needs very slight mechanical energy for oscillation. The oscillator plate was installed at three positions for the horizontal and vertical PCM heat sink: i) the middle of the hot plate, ii) the bottom of the hot plate, and iii) the corner of the heat sink. A computational fluid dynamics model has been employed to model the PCM melting process and evaluate the induced mixing heat flow and its effect on natural convection. A new mechanical method using vibration energy accelerates heat flow to improve heat transfer and thermal energy absorption. The results reveal that in the best case with transversal oscillation at the corner of the heat sink, the melting rate and heat transfer rate (Nusselt number) increase by 39 % and 64.2 % compared to no vibration case, respectively. Also, the absorbed heat energy rate (AHR) within the PCM heat sink is elevated from 0.51 to 0.79 (54.9 %), while the oscillator just consumed as small as 438 mJ of mechanical energy, reflecting this mechanical approach's uniqueness.

Numerical investigation and artificial brain structure-based modeling to predict the heat transfer of hybrid Ag/Au nanofluid in a helical tube heat exchanger

In recent years, due to the low thermal coefficients of common fluids and the increase in size and cost of heat exchangers, technologies for improving heat transfer and reducing dimensions have been developed and widely used in industries such as refrigeration, cooling of processing cells, chemical industries, and more. Previously, increasing heat exchange capacity in heat exchangers was achieved by altering parameters such as boundary conditions, flow geometry, heat exchanger geometry, or changing the type of fluid. Additionally, apart from the use of nanofluids, various other operational methods can be employed to improve the thermal performance of heat exchangers. Accordingly, considering the combination of the aforementioned innovative techniques, this study presents the modeling of flow and heat transfer inside helically coiled tube heat exchangers under the flow of nanofluids containing nickel, gold, silver, and gold/silver hybrid nanoparticles using numerical and artificial intelligence methods. In this study, the effect of variations in the inner diameter of the coiled tube and the volume fraction of nanoparticles was examined. The results showed that increasing the inner diameter and volume fraction of nanoparticles leads to an increase in heat transfer coefficient and Nusselt number, while the friction factor decreases with an increase in Reynolds number and increases with an increase in diameter and volume fraction. Finally, the accuracy and validity of the model were evaluated using statistical parameters and experimental results, which showed a 99.9% level of agreement between the predicted and experimental outcomes.

Laminar Natural Convection of Water-Based Alumina Nanofluids in a Square Enclosure

Steady-state, laminar, natural convection of water-based alumina nanofluids in a square enclosure with partial heating from the bottom and symmetrical cooling from the sides has been investigated based on numerical simulations. The effects of Rayleigh number, normalized heat source length and nanoparticle volume fraction on the heat transfer behavior have been investigated. An increase in Rayleigh number, for given values of normalized heat source length and nanoparticle volume fraction, leads to an increase in Nusselt number. For a given set of values of Rayleigh number based on base-fluid properties and normalized heat source length, the Nusselt number does not vary significantly with increasing nanoparticle volume fraction because the strengthening viscous effects with increasing volume fraction for water-based alumina nanofluids counteracts the enhanced thermal diffusion in nanofluids. However, when effective Rayleigh number is based on nanofluid properties, Nusselt number decreases with increasing nanoparticle volume fraction. For a given set of values of Rayleigh number and nanoparticle volume fraction, the Nusselt number increases with increasing normalized heat source length due to the strengthening of advective transport. A correlation for mean Nusselt number is proposed which adequately captures qualitative and quantitative behavior obtained from the simulations across the considered parameter range.

Second Law Analysis for Free Convection in an L-Shaped Cavity Filled with Nanofluid

The paper aims to analyze the effects of various Prandtl number and different nanoparticles for heat transfer and entropy generation of free convection laminar fluid flow in an L-shaped cavity filled by nanofluid. To investigate the second law characteristics of free convective flow and heat transfer from an L- shaped geometry filled by water and nanofluids (Cu-water, Ag-water, Al2O3-water), the effects of Prandtl number and various nanoparticles on the average Nusselt number, total entropy generation and Bejan number has been numerically analyzed. Isotherms, stream function and entropy generation caused by heat transfer are also presented for various Prandtl numbers and various nanoparticles. The governing equations are solved using penalty finite element method with Galerkins weighted residual technique. The results reveal that Ag-water nanofluid with highest Prandtl number gives the highest amount of irreversibility as well as rate of heat transfer. Cu-water and Ag-water nanofluid produces more irreversibilities than Al2O3-water nanofluid and base fluid. Also the results show that the Nusselt number and Bejan number increase with the increase of Prandtl number. Therefore, Prandtl number may be an important parameter for desired heat transfer increment with decreasing entropy generation in the given geometry.

Entropy generation of Al2O3/water nanofluid in corrugated channels

The flow of nanofluids in a corrugated channel has been shown to have a significant impact on heat transfer performance, and has therefore become an important area of research. The ob- jective of this paper is to understand the thermal behavior of Al2O3/water nanofluid in a sinu-soidal and square channel and to identify ways to optimize heat transfer performance in such configurations. For this purpose, a numerical simulation was conducted using ANSYS-Fluent software 16.0 on entropy generation and thermo-hydraulic performance of a wavy channel with the two corrugation profiles (sinusoidal and square). The analyses were carried out under laminar forced convection flow conditions with constant heat flux boundary conditions on the walls. The influence of various parameters, such as particle concentration (0–5%), particle di-ameter (10nm , 40nm and 60nm), and Reynolds number (200 < Re < 800) on the heat transfer, thermal, and frictional entropy generation, and Bejan number was analyzed. Moreover, the distribution of streamlines and static temperature contours has been presented and discussed, and a correlation equation for the average Nusselt number based on the numerical results is presented. One of the most significant results obtained is that the inclusion of nanoparticles (5% volume fraction) in the base fluid yielded remarkable results, including up to 41.92% and 7.03% increase in average Nusselt number for sinusoidal and square channels, respectively. The sinusoidal channel exhibited the highest thermo-hydraulic performance at Re= 800 and φ= 5%, approximately THP= 1.6. In addition, the increase of nanoparticle concentration from 0% to 5% at Re= 800 and dnp= 10nm, diminishes the total entropy generation by 28.39 % and 22.12 % for sinusoidal and square channels, respectively, but when the nanoparticle diameter decreases from 60nm to 10nm at ϕ= 5% and Re= 800, the total entropy generation in the sinusoidal channel decreases by 34.85%, whereas in the square channel, it decreases by 20.05%. Therefore, rather than using a square channel, it is preferable and beneficial to use small values of nanoparticle diameter and large values for each of ϕ and Re in the sinusoidal wavy channel. Overall, the study of nanofluid flow in a wavy channel can provide valuable insights into the behavior of nanofluids and their potential applications in a variety of fields, including manufacturing, energy produc-tion, mining, agriculture, and environmental engineering.

Two-phase analysis of heat transfer of nanofluid flow in a cavity in the presence of a magnetic field, heating element, and a porous medium: A numerical approach

By increasing the efficiency of heating systems, more heat flux can be transferred in a certain dimension, thus lowering the operating temperature, or a specific heat flux can be transferred using a smaller heat exchanger. In this study, the flow of a Newtonian nanofluid in a square cavity containing a heating element filled with a porous medium is simulated under the effect of a uniform magnetic field in different rotation angles. The finite volume method (FVM) and two-phase mixture model were used. Water is used as the base fluid and Al2O3 nanoparticles are used as the solid nanoparticles. The heating element inside the cavity, which is filled with porous medium with porosity percentage ε moves up or down to the width of the element. The fields of velocity, streamlines, and temperature are physically plotted, and Nusselt number and entropy generations diagrams are plotted. The results show that the change in the angle of the cavity and the change in position of the heating element on the hot wall have significant effects on the physical patterns. Other results indicate that with increasing volume fraction of nanoparticles and Rayleigh number (Ra), Nusselt number increases. Also, increasing the volume fraction of nanoparticles and Hartmann number (Ha) decreases the entropy generation due to heat transfer and increases the entropy generation due to friction. Also, it was found that in the cavity without a heating element, with increasing θ, the amount of local velocity increases in more places; so that, in case A and θ=90°, it reaches its maximum value in the cavity without a heating element. As can be seen, by placing the heating element at θ=0°, the maximum local velocity occurs above the heating element. Gradually, this value decreases with increasing the angle of the cavity filled with the porous medium relative to the x-axis to reach its minimum value in the cavity with θ=90°.

Computational analysis and biomechanical study of Oldroyd-B fluid with homogeneous and heterogeneous reactions through a vertical non-uniform channel

Abstract Homogeneous and heterogeneous reactions play a decisive role in biological procedures such as burning, polymer creation, ceramic construction, distillation, and catalysis. The magnetic properties of hemoglobin molecules are organic. Magnetic resonance imaging (MRI) and electronic components with an electromagnetic field are now readily available, allowing for the explanation of fundamental biological processes. These ideas form the foundation of an ongoing study that attempts to look into the impact of both homogeneous and heterogeneous reactivity on the peristaltic transport of magnetohydrodynamics Oldroyd-B fluid. When convective and partial sliding conditions are present, the configuration changes to a non-uniform vertical channel. The fundamental partial differential equations are resolved utilizing the Homotopy Analysis Method. Entropy optimization has been carried out. The primary limits entering the problem are investigated, and then a graph is used to show the influences of temperature, velocity, skin fraction, Nusselt number, and pressure increase against mean circulation, trapping phenomena, homogeneous reactions, and heterogeneous way to respond. When magnetic parameter rises, the velocity of Oldroyd-B fluid and Bejan number decrease, while temperature, entropy generation, and pressure gradient increase. The tables show that the skin friction coefficient rises for accumulative values of the Grashof number and magnetic parameter, while the skin friction coefficient drops for rising values of the velocity slip parameter and Reynolds number. The Nusselt number increases for large values of Eckert, Grashof numbers, and magnetic parameters.

ANALYSIS OF UNSTEADY FREE CONVECTION OVER A VERTICAL PLATE FOR KEROSENE-BASED NANOFLUID

An analysis of kerosene-based nanofluid flow past a semi-infinite vertical plate is carried out numerically. A set of unsteady, nonlinear governing equations are derived, namely, the momentum, energy, continuity, and concentration equations. The Crank-Nicolson implicit finite difference scheme is used to solve the governing equations. It is unconditionally stable. Based on different values of physical parameters, the velocity, temperature, and concentration profiles across the boundary layer are depicted. Graphs comparing the heat transfer characteristics of Newtonian fluids with local and average, skin friction, Nusselt number, and Sherwood number are provided. With an increasing value of the Prandtl number of kerosene-based nanofluid the local skin friction coefficient decreases while the Nusselt number increases. Furthermore, the Sherwood number decreases as the Prandtl number increases.