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Recent studies indicate that nanofluids are crucial for solar heat exchange operations and solar energy collectors. Furthermore, the importance of energy and mass transfer in entropy creation is significantly increased in a number of industrial and engineering processes, such as mechanical power collectors, air conditioning, food processing, refrigeration, and heat exchangers. As a result of this advancement, this research is aimed to explore the comparative study on bioconvective Darcy–Forchheimer flow of an incompressible hydromagnetic Ree–Eyring nanofluid over a chemically activated expanding sheet in suction and injection cases while including the consequences of radiation, energy generation, and convective boundary conditions. Boundary layer approximation is utilized to represent this investigation’s primary partial differential equations (PDE). Then, using the appropriate transformation, the models are rebuilt into nonlinear ordinary differential equations (ODE). Utilizing the BVP5C inbuilt MATLAB package, the numerical solutions for this examination are established. Further, the graphical and tabular representations allow us to analyze the impacts of several relevant features on the microorganism’s density, concentration, entropy creation, velocity, temperature, friction factor, Sherwood, and Nusselt number distribution. The outcomes reveal that the velocity field of the liquid movement is declined by applying positive amounts of the Darcy–Forchheimer and magnetic parameters, respectively. Boosting values of the radiation, thermal ratio parameter, and temperature Biot number assist an increase in the thermal field. It reveals the augmented entropy generation with the rising values of bioconvection Lewis number and Brinkman number. Furthermore, the mass transfer rate increases with larger values of the Brownian parameter and chemical reaction parameter. [ABSTRACT FROM AUTHOR]

The use of hybrid nanofluids (HNF) in heat transfer applications has become the subject of studies during recent periods. Its ability to transfer heat is superior to single nanofluids, and this has been proven in many research. Shell and tube heat exchanger is one of the most common types and are therefore always under research to improve their performance. This study is a practical study that examines the effectiveness of HNF in their use as operating fluids in shell-and-tube heat exchangers instead of traditional operating fluids. A laboratory heat exchanger was used to complete this study. A group of HNF (MWCNTs- Al2O3/water) was synthesized at different concentration rates ranging from 0.4 to 2%. Tests were conducted for Reynolds values in the range from 2500 to 12,560. By measuring the variables in the tests and calculating some factors the results showed that, in comparison between the use of HNF and distilled water, it was found that there is an increase in the value of the Nusselt number for the HNF over the distilled water in a range of 10- 28.5%. The effectiveness increased when using the HNF by up to 22.7% compared to distilled water. Through experiments, an equation was deduced to calculate the value of the Nusselt number. There is good agreement between the results of this research and previous literature. [ABSTRACT FROM AUTHOR]

A novel mathematical technique for an unsteady bioconvective flow of Williamson nanofluids over a vertical wavy cone in the presence of non-linear radiation and viscous dissipation impacts is investigated. The cone surface is described by a sinusoidal function while the components of the extra stress tensor are presented in terms of the dynamic viscosity. The irregular wavy surface is referred to the convective boundary conditions and nanoparticle passively controls conditions. The governing equations are presented in general forms then the condition $$G{r_L} \to \infty $$ G r L → ∞ and suitable transformations are used to map the wavy cone to regular domain. A fully implicit finite differences method (FDM) is applied to solve the converted system and wide ranges of independent variables are assumed. $$0 \le X\le 7, 0 \le Y\le 25$$ 0 ≤ X ≤ 7 , 0 ≤ Y ≤ 25. The major outcomes disclosed that the increase in the Williamson number $$We$$ We causes a reduction the nanofluid flow while the skin friction coefficient is rising. Further, there is an enhancement in the values of the Nusselt number up to 75% is obtained as Biot number $$Bi$$ Bi is altered from 0.1 to 0.4. Also, the convective boundary conditions in presence of the non-linear radiations are recommended to enhance the velocity, temperature and rate of the heat transfer. [ABSTRACT FROM AUTHOR]

The laminar natural convection heat transfer from isothermally heated, narrow flat plates oriented at different angles of rotation is experimentally and numerically studied. The heated flat plate is narrow, i.e., has a relatively small width, w, to length, l, ratio, and is embedded in a plane adiabatic surface within which the heated plate can be oriented at different angles of rotation. The three-dimensional governing equations for geometrical assessment were solved numerically in terms of non-dimensional variables using finite volume-based solution. Model results for the average Nusselt number were obtained for a relatively wide range of non-dimensional variables included the Rayleigh number ranging from 1 × 103 ≤ Ra ≤ 1 × 108, non-dimensional plate width ranging from 0.15 ≤ W ≤ 1, and angle of rotation ranging from 0° ≤ α ≤ 90°. On the other hand, experimental results for the average Nusselt number were obtained for a narrower range of non-dimensional variables included the Rayleigh number ranged from 5.98 × 103 ≤ Ra ≤ 1.18 × 105, the angle of rotation ranged from 0° ≤ α ≤ 90°, and the non-dimensional plate width was fixed at 0.4. Additionally, air with a Prandtl number of 0.7 was used as the working fluid in the study. Model results were validated against present experimental results and existing correlations. The effects of these non-dimensional variables on the average and local Nusselt numbers for the heated flat plate were investigated. It was found that in some situations the non-dimensional variables have a significant effect on heat transfer rate from the heated flat plate. Correlations to calculate the average Nusselt number for the heated flat plate were developed. [ABSTRACT FROM AUTHOR]

Several studies have demonstrated that flexible vortex generators exhibit higher hydrothermal efficiency than their rigid counterparts. The present study focuses on the implementation of a cylindrical rigid obstacle located in the vicinity of the inlet of a mini channel. Downstream, several flexible beams are attached to the channel walls, oscillating due to the forces exerted by the Von-Karmann vortex street generated by the cylinder. The Reynolds number is sufficiently low to maintain a laminar regime throughout the mini channel. A parametric analysis is conducted to explore the performance of various configurations of flexible beams with differing numbers, heights, and inter-distances. The hydrodynamic, thermal, and hydrothermal performance of the mini channel is evaluated using the time average friction factor, Nusselt number, and thermal efficiency factor. Results indicate that the presence of flexible beams significantly enhances heat transfer. The best configuration increases the overall thermal efficiency by 45%, while elevating the heat transfer and mechanical loss by 3.05 and 8.52 times, respectively, in comparison with an empty mini channel. [ABSTRACT FROM AUTHOR]

Investigation of turbulent mixed convection of different working fluids, namely, pure water, CuO/water nanofluid, n-octadecane/water nanofluid (or slurry), and a hybrid water-based suspension of CuO and n-octadecane nanoparticles in a uniformly heated vertical square channel is carried out. The shear stress transport/kappa-omega model is applied to simulate the turbulent flow. Eulerian–Lagrangian two phase model and homogeneous model are employed to simulate the nanofluid flow. It is shown that Eulerian–Lagrangian two-phase model predicts higher Nusselt number and friction factor than single-phase model and the results of two-phase model are closer to experimental data. It is found that a new hybrid nanofluid with dispersed nano-encapsulated phase change material particles provides better thermal and hydrodynamic performances compared to other nanofluids. Slurry containing 5% n-octadecane provides an improvement of nearly 37.2%, while hybrid nanofluid (1% CuO + 5% n-octadecane) offers added convective heat transfer enhancement of almost 60%. With increasing volume fraction, friction factor becomes slightly larger than that of pure water. For 5% n-octadecane/water and 1% CuO + 5% n-octadecane/water nanofluids, friction factor increases by 2.5% and 1.7%, respectively. Due to dominance of thermal entropy generation, total entropy generation reduces by increasing Reynolds number and volume fraction. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to numerically investigate the influence of the entrance geometry and thermal boundary conditions on the local and averaged heat transfer coefficient in a ribbed rectangular channel with an aspect ratio of 5. Ribs, angled at 45°, were periodically deployed on one or two opposite sides, while the remaining walls of the rectangular channel were assumed to be smooth and unheated. The effect of entrance conditions was addressed by considering either a smooth or a ribbed unheated section upstream of the ribbed heated section. The effect of the thermal boundary condition was studied by considering a uniform heat flux imposed at the inter-rib region, or at the inter-rib and the rib baseplate, or at the whole interface between the ribbed surface and the coolant. Results, presented in the form of spatially resolved and spatially averaged Nusselt numbers, show that a ribbed section preceding the heated test section affects the heat transfer coefficient, relative to a smooth entrance section, for several repetitive modules. The influence of the thermal boundary condition was found to be mainly concentrated in the surface regions immediately upstream and downstream of each rib, with small differences, in terms of spatially averaged Nusselt numbers. The presented investigation is meant to point out that heat transfer experiments on ribbed channels, massively provided by the heat transfer community according to the current technical literature, should provide an exhaustive description of the entrance and thermal boundary conditions assumed in the experiments and eventually to discuss how they could potentially affect the results. [ABSTRACT FROM AUTHOR]

Further Consideration On The Two-pass Channel Flow Is Still Necessary Due To The Complexity Of 180-deg Turn, Rotation, And Wall Ribs. Numerical Investigations Have Repeatedly Revealed Differences From Experiments, With The Primary Focus Of The Smooth Walls. Thus, This Work Deals With Newly Added Ribs And Three-equation Variant Of The Shear Stress Transport (Sst) K–ω Model To The Current Fluid Flow And Heat Transfer Depending On An Existing Experiment As A Reference. The Adapted Turbulence Model Thought To Be More Susceptible To U-bend Zone, Rotation, And Wall Corrugation Is Applied Using COMSOLMULTIPHYSICS Program. A Two-pass Profile With Leafy Characteristics, Derived From A Prior Work By The First Author, Is Implemented For The First Time And Contrasted Against Alternative Corrugation Designs. The Findings Demonstrated That Applying The Suggested Model Reduces The Percentage Error Between The Computational And Experimental Data To Less Than 20%. The Nusselt Numbers Computed At Different Leafy-corrugated Channel Divisions Are Augmented To 30% With 70% Surface Temperature Reduction; However, The Friction Penalty Rises Too. [ABSTRACT FROM AUTHOR]

The design of various biomedical, electronics cooling, and microfluidic devices relies on geometry-specific models and empirical correlations for flow and heat transfer through microscale pin fin geometries. Machine learning (ML) techniques are being used across many branches of science to develop more generalized surrogate models that can predict such transport processes. To collapse the simulation of flow and thermal properties across many different pin fin surfaces into a single predictive tool, the present study develops machine-learning-based surrogate models for the friction factor and Nusselt number (for constant wall temperature conditions) for fully developed low Reynolds number flow across pin fin geometries of differing cross section shape (circular, square, triangular) in aligned or staggered arrangements, oriented at any angle to the incoming flow, and for a range of transverse and longitudinal pitches, with water as the working fluid. The model training data are generated using an automated workflow that allows thousands of numerical simulations to be carried out on across different geometric and flow configurations. A total of ∼14,800 distinct simulation cases, for both friction factor and Nusselt number, are generated while varying the Reynolds number and aforementioned geometric parameters to train and test the machine learning models. The machine learning model architecture takes inputs of both image and vector data, and then outputs a scalar friction factor or Nusselt number. The trained models yield a goodness of fit (R2) value of 0.98 on unseen data. [ABSTRACT FROM AUTHOR]

Double pipe heat exchangers, or DPHEs, are employed in the power, oil, and process sectors. They cannot handle demanding applications. They have restrictions if they have to be utilized for heavy-duty applications. To get beyond these restrictions and use them for heavy-duty applications, heat transmission must be improved. In this work, a DPHE fitted with bowl-cut twisted tapes at different scale ratios (25, 50, and 75%) width (D) of bowl-cut from the center and circulated with TiO2/CuO hybrid nanofluids (NFs) is studied to assess its friction factor, thermal performance factor and Nusselt number. The working fluid was TiO2/CuO hybrid nanofluids (NFs) at varying concentrations (0.01, 0.03, and 0.05%) with Reynolds numbers from 2000 to 12,000. The bowl-cut twisted tape's twisted ratio (H/D = 3) was kept constant. The hybrid NFs' Nusselt number improvement was 66.09% more than that of the conventional tube. For varying scale ratios, the improvement in heat transfer was found to be 83.35, 115.31, and 172% with the bowl-cut twisted tapes and hybrid NFs. It was discovered that the friction factor penalty was 8.28, 0.83, and 1.075 times greater than that of the carrier fluid. Additionally, it was noticed that the thermal performance factor (TPF) was 1.65 times higher than the original fluid. [ABSTRACT FROM AUTHOR]

This study evaluates the unsteady laminar flow and heat and mass transfer of a nanofluid in the appearance of gyrotactic microorganisms. In this analysis, using the Darcy–Forchheimer flow inside the vicinity of a nonlinearly stretched surface with Brownian motion and thermophoresis impacts. Similarity conversion is familiar with reduced governing models into dimensionless variables, and "bvp4c," a MATLAB solver, is employed to find the computational outputs of this analysis. This analysis reports that the use of nanofluids provides better thermal characteristics which are helpful to enhance the heat transfer coefficient. Graphs for this analysis are created for distinct values of non-dimensionless parameters, whereas the coefficient of surface drag, heat flux, mass flux, and rate of microorganism density are all interpreted numerically and graphically. The high level of resistance provided by velocity slip and Forchheimer parameters leads to a decrease in velocity curves while an increment is seen in the temperature profile. It is also remarked that bioconvection Peclet number induces a decrement in the density distribution of motile microorganisms. In addition, it has been observed that the Nusselt number for a nonlinear stretching sheet is better as compared to a linear stretching sheet. [ABSTRACT FROM AUTHOR]

The paper's primary goal is to investigate mass and heat transfer processes in reactive nanofluid particles. Within Buongiorno's model, three chemical reactions are discussed. The main subject is on the nanoparticle fractions at the boundary. The characteristics of N t and N b with regard to the nanoparticle fraction have been found to be passively rather than actively controlled at the boundary. To put it another way, these qualities naturally develop and are controlled by the circumstances at the boundary or interface where the nanoparticles interact with the surrounding medium. They are not the result of active manipulation or outside forces. The system of partial differential equations was converted into ordinary differential equations using similarity transformations. To solve the system of ODEs, they combined the shooting method with a numerical technique known as RK-Fehlberg. The study examines various physical parameters and their effects using graphs. The paper also contains a table showing how different parameters affect the regional Nusselt and Sherwood numbers. This enables a deeper comprehension of the impact that these variables have on the heat and mass transfer within the reactive nanofluid particles. Core findings: Examining three chemical reactions involving nanofluids has led to the study's key discoveries. Additionally, it looks into how specific physical variables may affect the Nusselt and Sherwood numbers. [ABSTRACT FROM AUTHOR]

This investigation uses the Tiwari and Das nanofluid model to enhance the heat transfer rate in Sutterby nanofluid over a Riga plate. The effects of heat source/sink, viscosity dispersion, and mass flow for water-based fluids are also considered in this work. Sutterby fluid has been utilized to investigate the rheological features of nanofluids. The transverse Lorentz force produced by the Riga plate assists in the flow down the plate by producing an electromagnetic field. The main aim of this investigation is to evaluate the presence of two different types of nanoparticles in water, specifically silicon carbide (SiC) and copper (Cu). Dimensionless variables are first used to convert the mathematical model into a non-dimensional form. The similarity approach is then used to further rewrite the non-dimensional partial differential equations into a set of similarity equations. The bvp4c function in MATLAB software provides a numerical solution to these equations. The effects on temperature and velocity profiles of many physical factors, including the Reynold number, heat source/sink, and Deborah number, have been analyzed and presented. Furthermore, using tables, a detailed analysis of the skin friction coefficient and local Nusselt numbers is conducted. The results show that convective flow is suppressed when solid nanoparticles are added to the base fluid. The velocity distribution improves as Deborah and Reynold's numbers get a higher value. Also, the temperature field improves by incrementing exponential and thermal heat source/sink parameters. [ABSTRACT FROM AUTHOR]

This paper examines the three-dimensional flow of a bio-hybrid nanofluid through a porous rotating disk while considering the effects of linear thermal radiation and quadratic thermal radiation and examining entropy generation. The fluid enclosure with blood is taken as base fluid and silver–gold is considered as nanoparticles. The fluid flow phenomenon is characterized by nonlinear coupled differential equations involving two or more independent variables. A suitable numerical technique is used to handle the set of governing equations along with a stability and convergence analysis, followed by applying the homotopy perturbation method for solving stated equations. Through graphical illustrations, the radial and tangential velocity distributions, temperature distributions, entropy production and Bejan number are discussed graphically. The Nusselt number and friction factor results are presented and analyzed. The current finding is validated using the available data in both the numerical and homotopy perturbation methods. The results show that when heat absorption increases on blood/gold–silver hybrid nanofluid, a large heat flux develops on the revolving disk, accelerating the heat-transfer mechanism from that surface in both linear thermal radiation and quadratic thermal radiation cases. Moreover, we have seen that the entropy generation is increasing as the magnetic interaction parameter and heat absorption/generation coefficient in quadratic thermal radiation grow, in comparison with linear thermal radiation. The application of thermal radiation and entropy generation analysis is significantly used in the study of renal artery stenosis (RAS) systems and is an active area of research in the field of biomedical engineering. The model is utilized to compute entropy in physiological systems, such as cancer treatment, heat transfer in tissues, dialysis blood pump, and the efficacy of medical apparatus. [ABSTRACT FROM AUTHOR]

This study investigates the significance of single-walled (SWCNTs) and multi-walled (MWCNTs) carbon nanotubes with a convectional fluid (water) over a vertical cone under the influences of chemical reaction, magnetic field, thermal radiation and saturated porous media. The impact of heat sources is also examined. Based on the flow assumptions, the fundamental flow equations are modeled as partial differential equations (PDEs). Using the appropriate transformation, the PDEs are converted to ordinary differential equations and then solved via RK4 in MATLAB. To confirm the results, a comparison is made with a previously investigated problem, finding good agreement. The emerging dimensionless physical parameters impact on the flow problem is determined through graphs and tables. Analysis reveals a dual solution for the suction and injection parameter. Therefore, stability examination is implemented to confirm a stable solution. The aim of the study is to analyze SWCTs and MWCTs in a vertical cone with stability to establish that only the first solution is reliable. The analysis here signifies that large volume fractions can be substituted to increase the nanofluid movement. The mathematical model and graphical demonstration indicate that the velocity of MWCNTs is higher than SWCNTs. Moreover, the local skin friction, rate of heat transfer, and Nusselt and Sherwood numbers improve with Biot number. [ABSTRACT FROM AUTHOR]

Using the RANS approach with the standard k-ω turbulence model, this study offers a novel investigation into the dynamic and thermal properties of turbulent impinging jet arrays. Our study examines the combined effect of the number of jets (N) and the jet–jet spacing (S) on flow mechanisms and heat transfer performance, which is unique compared to previous research that frequently focuses on the individual effects of parameters. Through the investigation of the turbulent kinetic energy, friction coefficient, velocity contours, streamlines, pressure contours, and local and mean Nusselt numbers, we provide important information about how these parameters impact flow dynamics. Local heat transfer in the central and lateral zones is greatly improved by increasing the number of jets (N) and the jet–jet spacing (S), according to our findings. When the jet–jet spacing (S) is increased from 1 to 4, the maximum value of the Nusselt number along the central zone improves by 21.2%. Furthermore, the best improvement in the maximum Nusselt number (24.5%) along the lateral zone is obtained by increasing the number of jets (N) from 5 to 11 for the lower value of jet–jet spacing S = 1. It has also been noted that lower jet-plate distance (H), lower jet–jet spacing (S), and a higher number of jets (N) result in better average heat transfer. To predict the average Nusselt number based on three parameters (N, S, and H), we establish a critical correlation, which provides a useful tool for optimizing impinging jet configurations in a variety of engineering applications. The diversification of the parameters studied and the thorough analysis in this study add important new results to the field by demonstrating the significant effects of the number of jets, jet–jet spacing, and jet-plate distance on the thermal and dynamic behavior of impinging jet arrays. [ABSTRACT FROM AUTHOR]

This paper studies the similarity of silver-blood-based Carreau–Maxwell, Carreau–Oldroyd-B and Carreau–Jeffrey binary nanofluids on the parabolic trough solar collector. By the energy equations, Joule heating effects and nonlinear thermal radiation were integrated. The velocity slip condition by the solid–liquid interface was again worked out. In this model, magnetic field aspects and viscous dissipation were again taken into account. The converted construction was modeled into ordinary differential methods with the help of appropriate comparison applications. This governing relation on current flow problem was given graphically and determined mathematically by applying made-up MATLAB computational tool with the aid of renowned mathematical shooting methods bvp4c (Lobatto's IIIa Formulae). This mathematical outcomes are given in tabular and graphical models. It was observed that the nonlinear thermal radiation aggregates the temperature profile. This skin friction was improved for greater values of magnetic parameter by 6.16%. Moreover, the local Nusselt number was reduced about developing values of radiation parameter into 71.78%. Moreover, these Casson–Jeffrey and Casson–Maxwell nanofluid models are more efficient than the Casson–Oldroyd-B nanofluid models. [ABSTRACT FROM AUTHOR]

This paper provides an innovative idea to perform the analysis of entropy generation in the time-dependent flow of Williamson liquid toward an oscillating curvy porous surface. The characteristics of the transport phenomenon are improved by taking thermal and mass relaxation parameters in the energy and concentration equations respectively by utilizing a modulated form of Fourier and Fick laws known as Cattaneo–Christov heat and mass flux models. The mathematical form of the entire flow model is simplified by incorporating a curvilinear coordinate system. The obtained set of partial differential equations is then solved by the homotopy analysis method (HAM) which transforms them into convergent series form. The effects of various pertinent flow parameters on dimensionless pressure, entropy generation, velocity, and temperature fields are shown graphically. Furthermore, the variations in Sherwood number, skin friction coefficient, and local Nusselt number are presented in tabular form. It is observed from this study that the temperature and entropy generation increase with the radius of curvature parameter. [ABSTRACT FROM AUTHOR]

Within the realm of industrial energy conservation, the optimization of heat exchanger performance is paramount for the augmentation of energy utilization efficiency. This investigation employs computational fluid dynamics (CFD) simulations to elucidate the effects of an innovative DNA-Inspired Slotted Insert (DSI) on the convective heat transfer and pressure drop characteristics within heat exchange tubes. The study provides a thorough analysis of fully turbulent flow (Re = 6600–17,200), examining the effects of various DSI pitches, key lengths, and geometries. The findings reveal that the DSI instigates a three-dimensional spiral flow pattern, which is accompanied by an escalation in the Nusselt number (Nu) and friction factor (f) with increasing Reynolds numbers. An inverse relationship between Nu and both pitch and key length is observed; conversely, f exhibits a direct correlation with these parameters. The study identifies an optimal configuration characterized by a pitch of 10 mm and a key length of 1.5 mm, with square keys demonstrating superior heat transfer performance relative to other geometrical configurations. This research contributes significant design and application insights for double-helical inserts, which are pivotal for the enhancement of heat exchanger efficiency. [ABSTRACT FROM AUTHOR]

As the environmental crisis intensifies, the demand for energy-efficient systems has never been greater. Vortex generators have emerged as an effective method for enhancing heat transfer within tubes. While extensive research has been conducted on their application in straight tubes, studies focusing on their performance in curved tubes remain limited. This simulation study examined three different arrangements of triangular vortex generators in a common flow-down configuration within a U-turn tube to optimize heat transfer. The analysis conducted under constant wall temperature conditions across a range of Reynolds numbers spans both laminar and turbulent flow regimes to evaluate the broader impacts of vortex generators on flow and thermal fields. The efficiency of each arrangement was evaluated based on the Nusselt number and friction factor. Results show a remarkable increase in the Nusselt number, reaching up to 115% for the configuration with the highest number of vortex generators. However, this enhancement was accompanied by a significant increase in the friction factor, rising by up to 383% at higher Reynolds numbers. Overall, vortex generators demonstrated their highest effectiveness in curved tubes during the laminar-to-turbulent flow transition. In fully turbulent flow, the friction factor increased disproportionately to the modest gains in heat transfer. Despite these limitations, the use of vortex generators in curved tubes offers promising efficiency improvements and merits further exploration. [ABSTRACT FROM AUTHOR]

The heat transfer and fluid flow characteristics of microchannel with discrete double inclined ribs on sidewalls is performed numerically. A three-dimensional numerical model of the microchannel is constructed and studied. To obtain the optimal microchannel, four structural parameters of the rib length, angle, thickness, and height are changed by the orthogonal test method. In addition, four structural parameters of the rib are investigated separately on the heat transfer and fluid flow characteristics of the microchannel, Nusselt number, friction factor and performance evaluation criterion of the microchannel are calculated with Reynolds number ranging from 200 to 600. Results indicate that the microchannel with discrete double inclined ribs on sidewalls exhibits superior thermal characteristics, which shows a 58.13% reduction in temperature difference between the maximum temperature and the inlet temperature compared to the straight-through channel. Furthermore, all four structural parameters of the rib have varying degrees of effect on the heat transfer and fluid flow characteristics of the microchannel. [ABSTRACT FROM AUTHOR]

This study presents a novel hybrid roughness configuration for solar heat collectors (SHCs), combining wired roughness and protrusion rib roughness to address the global demand for sustainable energy solutions. By leveraging wired roughness to induce localized turbulence near the absorber plate and protrusion ribs to disrupt the laminar sublayer without adding significant material mass, the proposed design enhances thermal performance while minimizing environmental and economic costs. The experimental investigation evaluates the effects of relative roughness width (W/w), gap width (d/e), and relative rib height (e/D) on the Nusselt number (Nu), friction factor (f), and thermohydraulic performance parameter (THPP). Results highlight the optimal configuration of W/w = 5, d/e = 4, and e/D = 0.045, achieving a maximum THPP of 3.20 at a Reynolds number of 19,000. This configuration significantly improves heat transfer efficiency while maintaining hydraulic resistance within acceptable limits, offering a sustainable and cost-effective pathway to enhanced solar thermal energy systems. These findings provide a robust framework for advancing SHC technology, aligning with global sustainability goals by promoting renewable energy utilization and reducing dependence on fossil fuels. [ABSTRACT FROM AUTHOR]

Pin-fin cooling is a significant method for managing high temperatures in gas turbine blades during operation. This study recommends the employment of a pencil-shaped and a circular pin fin to improve the channel’s heat transfer efficiency, based on both experimental and computational examinations. Numerical simulations with Reynolds numbers ranging from 10,000 to 80,000 are used to explore and compare the flow and heat transfer properties of a wedge channel with three rows of staggered pencil and circular-shaped pin fins with a diameter of 12 mm. The investigation revealed that staggered arrangement of pencil pin fins affects flow pattern and heat transfer properties differently. Compared to the pencil pin fins, heat transfer is enhanced by 11.72%, and the pressure drop from pencil pin fins is minimized by 72.2%. Furthermore, compared to the smooth channel, the Nusselt number for circular fins shows an increase of 40%. When comparing pencil fins to the smooth channel, the Nusselt number increases by 18%. As a result compared to circular fins, the thermal performance factor increases by 35.2%. [ABSTRACT FROM AUTHOR]

This investigation discusses the significance of studying the behavior of non-Newtonian fluids, specifically the Casson fluid, subjected to an electrically conducting and stretching sheet. The study also explores the effects of an aligned magnetic field, Cattaneo–Christov double diffusion, viscous dissipation and chemical reactions on heat and mass transfer, respectively. The partial differential equations governing the flow problem are transformed into ordinary differential equations through the utilization of similarity transformations. Furthermore, the shooting technique is implemented in MATLAB to solve the ODEs. The influence of physical parameters, such as the magnetic field parameter, Eckert number, Prandtl number and chemical reaction parameter, on the velocity profile, temperature distribution, concentration profile, skin friction coefficient, Nusselt number and Sherwood number is studied and presented in graphical and tabular forms. It is found that increasing the Prandtl number causes a drop in the temperature profile. Moreover, the presence of thermal radiation and the Eckert number significantly amplifies the temperature distribution. When the magnetic number undergoes a substantial increase, there is a notable decrease in the velocity profile, and simultaneously, the temperature profile experiences a noticeable rise. Additionally, increase in the chemical reaction parameters leads to a decrease in the concentration profile. The skin friction coefficient, local Nusselt number and Sherwood number exhibit significant reductions as the Casson parameter increases. Additionally, a MATLAB built-in function named bvp4c is incorporated to verify the computed results. The practical implications of the Cattaneo–Christov heat flux model include microelectronics, microfluidic devices, processes involving rapid heating or cooling, such as laser welding or pulsed laser ablation and heat transfer in biological tissues. [ABSTRACT FROM AUTHOR]

An exact solution of steady state, electroosmotic, transient magnetohydrodynamic (MHD) flow, and heat transfer of a viscous and incompressible electrically conducting nanofluid consists of water and Cu metal, through a microparallel channel under the combined effect of pressure and vertically acting magnetic field is found. An exact solution is calculated through Laplace transform using the software of Mathematica to find the steady velocity and temperature field depending on many dimensionless parameters. The electromagnetic couple effect, the volumetric generation of heat caused by the Joule heating effect, and viscous dissipation are considered to analyze the thermally fully formed heat flow problem based on the steady part of the velocity field. The exact result of the temperature field is obtained by taking the uniform boundary heat flux. The significant parameter of heat flow known as the Nusselt number, depending on the height of the microtube, is defined. At last, the entropy generation of MHD temperature flow is analyzed. The interpretation of variations that occurred in internal and external entropy generations is given and consequences are explained. [ABSTRACT FROM AUTHOR]

The velocity slippage with combined effects of buoyancy force plays an important role in the extraction of crude oil since it reduces the pressure drop along the pipelines and well-bore. Due to this, it becomes difficult to push the oil out of the reservoir. So, the main goal is to analyse the velocity slip and no-slip on two immiscible viscous fluids flowing in a curved channel with viscous dissipation. To the best of the author's knowledge, there is no study given on two non-miscible laminar Newtonian layers of viscous-viscous fluids. The curved channel is divided into two regions and both regions are occupied with viscous fluids. The flow is caused by the constant pressure gradient and buoyancy force. The analytical solutions of highly nonlinear mathematical equations are obtained using perturbation series by taking ε (= Pr E c) ≪ 1. The impact of the curvature ratio parameter, velocity slips, Reynolds number, buoyancy force, viscosity ratio parameter, and height ratio parameter on heat and mass transfer are examined and presented through graphs. Moreover, the behaviour of shear stresses, skin drag and Nusselt number on both walls of the channel is analyzed and presented through bar charts. It is concluded that the velocities of the immiscible fluids augment by increasing the curvature parameter whereas the temperatures and shear stresses fall. It is also observed that the shear stress at the lower wall is more significant with a rise in curvature parameter in the case when velocity slippage is not considered as compared to velocity slippage. [ABSTRACT FROM AUTHOR]

This work undertakes a comprehensive investigation into the behavior of a novel Hall current, a non-uniform heat source/sink, and an nth-order chemical reaction in a three-dimensional (3D) Casson fluid transport towards a tilted stretched device. The research is characterized by its thoroughness, meticulously examining these occurrences. The Rosseland diffusion model, a mathematical framework used to describe the heat transfer process by radiation, was employed. After similarity transformations, the controlling partial differential equations become nonlinearly connected ordinary differential equations. We solve these equations numerically using Runge–Kutta fourth order with the shooting technique. Numerical solutions can be computed for the concentration, temperature, velocity, and Sherwood numbers. The necessary answers are not only analyzed through diagrams but also physical logic. It has been observed that when the hall parameter is increased, the dimensionless velocity field consistently shows an increasing trend. The Sherwood number rises in tandem with an increasing chemical reaction term, whereas the Nusselt number falls in the presence of a rising Casson fluid term. Various investigations validate the results, revealing their high level of accuracy. This investigation highlights the intricate interplay between electromagnetic, chemical, and non-Newtonian fluid dynamics, providing insights critical for optimizing industrial processes involving such fluids. The study’s findings are applicable in polymer processing, bioengineering, and chemical reaction engineering, where precise control of fluid flow and reaction rates is essential. [ABSTRACT FROM AUTHOR]