Skin Friction Coefficient Research Articles

Numerical Solutions for Radiative MHD Casson Nanofluid Flow with Slip, Heat Source, and Chemical Reactions over a Stretching Surface

MHD Casson nanofluid flow in the presence of viscous dissipation, thermal radiation and chemical reaction past a linear stretching surface is investigated. The problem is subjected to slip boundary conditions. The analysis of heat and mass transfer in the presence of Brownian motion and the thermophoretic diffusion effects are incorporated into heat and mass transfer. Nonlinear partial differential equations model governing the problems are transformed into the dimensionless nonlinear ordinary differential equations via similarity variables, then shooting method with sixth-order Runge- Kutta numerical scheme is used to solve the reduce system of Ordinary Differential Equations (ODE). Maple software is used to perform the simulation. The results are presented graphically and in tabular form and the conclusion is drawn that the flow field and other quantities of physical interest are significantly influenced by these parameters. Comparison between the obtained results and previous works are well in agreement. Numerical values of the local skin-friction, Nusselt number and nanoparticle Sherwood number are computed and analyzed. It is noted that the skin-friction coefficient decreases for the larger values of velocity ratio parameter, slip parameter, and increases with an increasing value of Casson parameter. It is also found that enhancing the chemical reaction parameter leads to decrease in concentration profile

EFFECTS OF LOCALIZED NON-GAUSSIAN ROUGHNESS ON HIGH PRESSURE TURBINE AERO-THERMAL PERFORMANCE: CONVECTIVE HEAT TRANSFER, SKIN-FRICTION AND THE REYNOLDS' ANALOGY

Abstract Compressible direct numerical simulations are conducted to investigate how surface roughness affects the aero-thermal performance of a high pressure turbine vane operating at an exit Reynolds number of 0.59 × 106 and exit Mach number of 0.92. The roughness under investigation here was synthesized with non- Gaussian statistical properties and an amplitude that varies over its chord length — representative of what truly occurs on an in-service vane. Particular attention is directed towards how sys- tematically changing the axial extent of leading edge roughness affects convective heat transfer (Nusselt and Stanton numbers) and aerodynamic drag (skin-friction coefficient) on the pressure and suction surfaces. The results of this investigation demonstrate that moving the larger amplitude roughness further along the suc- tion surface can cause major changes in the blade boundary-layer state. In fact, towards the trailing-edge of one of the rough vanes investigated here, the local skin-friction coefficient increases by a factor of twenty-three (2, 300%) compared to smooth-vane lev- els, whereas the local Stanton number increases by a factor six (600%). The disproportionate rise of drag compared to heat transfer is explored in further detail by quantifying the Reynolds' analogy and by calculating the fractional contributions of pres- sure drag and viscous drag to the total drag force. The effect of varying the inlet turbulence intensity and integral length-scale for a fixed roughness topography is also investigated, along with the Reynolds-number scaling of heat transfer and drag.

Observations on the structure of turbulent boundary layers interacting with embedded propeller tip vortices

The study presents observations on the interaction of double-blade propeller tip vortices with a smooth-wall turbulent boundary layer (TBL). The wall-bounded helicoidal vortices from the propeller modify the velocity profiles and turbulence statistics. The effects of two different tip clearances, $\epsilon = 0.1\delta _0$ and $0.5\delta _0$ , at a matched thrust, are explored with particle image velocimetry to understand the dynamics of tip-vortex formation within the logarithmic and wake regions of the boundary layer. The measurements are performed with $\lambda =U_{tip}/U_{\infty }$ in the range 5.3–5.9, and a blade passing frequency ( $\,f_{prop}$ ) of the same order of the boundary-layer time scale ( $\,f_{TBL}$ ). Observations indicate a reduction in the extent of the log region and an enhancement of the wake parameter $\varPi$ , mirroring the behaviour seen in TBLs under adverse pressure gradient conditions. Notably, the slipstream most contracted region exhibits a significant reduction in the skin friction coefficient $C_f$ and an amplification of the velocity fluctuation statistics across the entire boundary layer. At a clearance of $\epsilon = 0.1\delta _0$ , there is evidence of the formation of paired coherent wall-bounded structures. The presence of the wall decreases the amplitude of both periodic and stochastic fluctuations obtained with a phase-locked triple decomposition. An exception is observed behind the propeller for the stochastic fluctuations of the wall-normal component of the flow, which become amplified as the blades move away from the wall. This leads to the creation of a more intense phase-locked two-point spatial coherence than that observed in fluctuations aligned with the streamwise direction. Furthermore, results reveal that reduced tip clearances lead to higher viscous dissipation and more active energy exchange between the mean flow and organized motions.

Aspects of heat transfer hybridized micropolar water-based iron oxide and silver nanoparticles across a stretching bidirectional sheet with thermal radiation

The hybridization of nanoparticles enhances heat transfer, playing a crucial role in the development of advanced thermal insulation materials. These materials find applications across diverse fields, including electronics design, healthcare, environmental remediation, and automotive engineering. In light of this, the current study investigates the boundary layer flow and heat transfer of hybridized (Fe3O4−H2O) and (Ag−Fe3O4−H2O) micropolar nanofluids over an extending bidirectional sheet characterized by nonlinear thermal radiation. The boundary heating conditions are based on two types of thermal settings in the energy equation: prescribed surface temperature (PST) and prescribed heat flux (PHF). The resulting partial differential equations are then converted into ordinary differential equations using specific similarity variables. The mathematical equations are solved using the Chebyshev Collocation Method (CCM). Consequently, a variety of graphs and tables are displayed to deliberate the impact of the emerging parameters on the flow and heat transmission processes. At the end, the analysis reveals that an increase in the temperature gradient is higher in a non-isothermal situation as compared to an isothermal case with growth in the Prandtl number. The material property helps to reduce surface drag and heat transfer, whereas the magnetic field increases the skin friction coefficient.

Entropy, thermal, and mass transportation optimization of magnetohydrodynamic power-law nanofluid over stretched sheet with chemical reaction effect

The power-law nanofluid’s heat and mass transmission over a stretched surface with magnetic field, entropy optimization, and chemical reaction effects is the main focus of the present study. The governing partial differential equations are reduced using similarity transformation into ODEs (ordinary differential equations), which are then numerically solved with the help of the Keller box and finite difference techniques. A substantial evaluation is conducted using the controlling flow factors, which include the Eckert number, chemical reaction factor, Brownian motion parameter, thermophoresis number, power-law index (n), and generalized Prandtl number (Pr), on the fluid velocity profile, flowing fluid temperature, and concentration profile. A decrease in the velocity profile is observed when the chemical reaction process is accelerated, leading to heat absorption. However, when the power-law parameter increases, the fluid’s temperature decreases, and the velocity profile increases at specific values of viscous dissipation (Ec = 0.1) and chemical reaction (γ = 0.01). The values of the coefficient of skin friction (Cf), Sherwood factor (Shx), and reduced local Nusselt number (Nux are also computed and presented in the form of a table for the generalized Prandtl number (Pr = 7.0). The coefficient of skin friction and mass transfer and heat transfer rates are quantitatively compared with those in the literature for particular circumstances, and the results demonstrate good agreement with each other. This research offers insightful information for designing and improving systems that use nanofluids exposed to external magnetic fields, which has ramifications in many technical uses, including heat exchange systems based on nanofluids and thermal management systems.

Magnetohydrodynamics of couple stress Casson fluid flow in a channel with stretching wall in the presence of dissipative and radiative heat transfer

AbstractThis paper investigates the unsteady magnetohydrodynamic flow of a couple stress Casson fluid between two parallel sheets where the heat transfer mechanism is incorporated with the influences of heat radiation, viscous dissipation, and Joule heating. The fluid flow is induced due to bi‐directional stretching of the lower sheet of the channel. The mathematical model of the physical problem is governed by highly nonlinear coupled partial differential equations with boundary conditions that are then transformed into highly nonlinear ordinary differential equations with boundary conditions using well‐defined similarity variables. The authors have used the well‐known computational technique called the spectral successive linearization method (SLM) to solve the obtained ordinary differential equations subject to the boundary conditions. Graphs and tables show the effects of non‐dimensional parameters on the important physical quantities such as the velocity and temperature profiles, and coefficients of skin‐frictions and heat transfer. The quadratic regression method is used to perform statistical analysis of Nusselt number and skin friction coefficients. The present investigation has significant applications in different problems of biomedical engineering, clinical sciences, industrial manufacturing processes, and so forth.

Analysis of thermal significances of nanofluids in inclined magnetized flow with Joule heating source and slip effects

The growing need for effective thermal management systems in engineering applications will improve performance by using nanofluids. Nanofluids, which show enhanced thermal characteristics compared to typical fluids, offer an effective way for heat transmission processes in industries. This study is particularly useful for systems where traditional fluids are insufficient for improving thermal performance. Understanding the overall impacts of Joule heating, magnetic fields, and slip conditions would be beneficial in fields such as aircraft, microelectronics, and biomedical engineering.The thermal significances of nanofluids in an inclined magnetized flow are analyzed in this work, taking slip effects and the Joule heating source into account. The motivation behind the current research is to investigate the flow and heat transfer behavior of magnetohydrodynamic (MHD) nanofluid under the influence of Joule heating in the presence of slip conditions.Based on conservation laws and suitable boundary conditions, the governing formulas for mass, momentum, energy, and nanoparticle concentration are developed. In this thermal investigation, unsteady nanofluid flow in two dimensions via a nonlinear stretched configuration is studied numerically together with an example of a non-uniform heat source. Using similarity transformation, the governing partial differential equation for chemical radiation and slip effects parameters for hydromagnetic flow is transformed into a set of ordinary differential equation (ODE). To solve these equations, a numerical method is applied. This study found that the velocity, mass transfer, temperature, concentration, heat transfer, and skin friction coefficient are significantly influenced by the chemical reaction, radiation parameter, and velocity slip. A graphical representation of the parameters influencing the heat transfer and the velocity changes in calculation is observed.

Magnetohydrodynamics (MHD) flow of ternary nanofluid and heat transfer past a permeable cylinder with velocity slip

The increasing demand for energy-efficient and environmentally sustainable solutions has driven the exploration of ternary nanofluids for enhanced heat transfer applications. This numerical study investigates the magnetohydrodynamics (MHD) flow and heat transfer characteristics of a ternary hybrid nanofluid (copper-alumina-titania/water) over a shrinking/stretching cylinder, considering the effects of velocity slip, suction, and curvature parameters. The variable wall temperature is also included in the physical model. The model in PDEs is transformed into a simplified version of differential equations (ODEs) which can be solved using the bvp4c solver. Validation against previously published data confirms the accuracy of the model. Two solutions are possible if the shrinking surface is permeable (with suction effect) while only unique solution for the stretching case. Surprisingly, the copper-alumina-titania/water exhibits a lower heat transfer rate but higher skin friction as compared to the copper-alumina/water. Specifically, the heat transfer coefficient decreases by 5-10% when incorporating the titania nanoparticle, while an increase of 8-12% for the skin friction coefficient. Additionally, the velocity slip and curvature parameters accelerate the boundary layer separation, whereas increased suction delays this process. These findings provide insights into optimizing thermal management systems using ternary hybrid nanofluids, particularly under MHD effects.

Numerical Study of Supersonic Cavity Flows with Different Turbulent Models

A numerical study of supersonic cavity flows is conducted with different turbulent models, including RANS, LES, DES, DDES, and IDDES. Firstly, a supersonic cavity-ramp flow with Ma∞ = 2.92 is simulated numerically. It shows that the results of DDES and IDDES are nearly equivalent. The wall skin-friction coefficients obtained by these two models are in better agreement with the experimental measurement than those of DES. The reason is that the RANS region of DDES and IDDES is larger than that of DES, so it produces more turbulence in the near-wall region. In comparison, RANS cannot accurately predict large separation flows. The shear layer’s reattachment point on the ramp predicted by RANS is biased downstream compared to the experimental measurement, making its overall prediction accuracy worse than other models. The results obtained by LES are comparable to those obtained by DDES and IDDES except for the wall skin-friction coefficient, which is much smaller because the grid resolution is not high enough to accurately resolve the near-wall turbulent flow. Secondly, the effect of different aft-wall angles (θ) on the flow characteristics of the supersonic cavity is investigated numerically with IDDES. We find that as θ decreases, the oscillation intensity of the cavity flow continuously decreases. However, the change in cavity drag with θ is non-monotonic, which means that there might be a critical θ at which the drag penalties of a cavity are minimal. Therefore, an optimal design should be achieved when changing θ to control the oscillation intensity of supersonic cavity flows.

Electro-Osmotic Mechanism of Ellis Fluid With Joule Heating, Viscous Dissipation, and Magnetic Field Effects in a Pumping Microtube.

The dynamics of electro-osmotically generated flow of biological viscoelastic fluid in a cylindrical geometry are investigated in this paper. This flux is the result of walls contracting and relaxing sinusoidally in a magnetic environment. The blood's viscoelasticity and shear-thinning viscosity are the primary causes of its non-Newtonian characteristics. Hence, the rheology of the fluid (blood) is accurately captured with the Ellis fluid model. Both Joule heating and viscous dissipation are accounted for during thermal analysis. The electric potential induced in the electric double layer (EDL) is obtained by applying the Debye-Huckel linearization to the nonlinear Poisson-Boltzmann equation. Mathematical modelling is incorporated in cylindrical coordinates in wave frame of reference. Assuming a long wavelength and creeping flow characterized by a low Reynolds number, the Ellis fluid model's governing equations are simplified. The resulting differential equations are evaluated numerically via the built-in tool NDSolve of the Mathematica. Graphical representations are utilized to visually and comprehensively assess the thermal characteristics, flow features, heat transfer coefficient, and skin friction coefficient. Various factors are taken into consideration, including the impact of Ellis fluid parameters, electric double layer, magnetic field, Brinkman number, and Ohmic dissipation. Ellis fluid's axial velocity boosts with a rise of the electro-osmotic parameter and power-law index while decreasing with an increase in the Hartmann number and material fluid parameter. The fluid temperature is directly proportional to EDL parameter and parameters of Ohmic and viscous dissipation. The presence of both electric and magnetic fields may aid in the management and control of Ellis fluid (blood) mobility at different temperatures, which is helpful in controlling bleeding during surgeries. The current model may be used in clinical scenarios involving the gastrointestinal system and capillaries, electrohydrodynamic therapy, delivery of drugs in pharmacological, and biomedical devices. This research creates a theoretical model that can predict the effects of different parameters on the characteristics of fluid flows that are like blood.

Chemical Reaction and Cross Diffusion Effects on Heat and Mass Transfer Characteristics of Viscoelastic Oil-Based Nanofluid Over a Porous Nonlinear Stretching Surface

The impact of chemical reaction and cross diffusion on heat and mass transport characteristics of viscoelastic flow of Al2O3 and CuO oil-based nanofluids past a porous nonlinear stretching surface has been examined. Similarity transformation was used to transform the governing partial differential equations into coupled nonlinear ordinary differential equations and solved numerically by employing the fourth order Runge-Kutta algorithm with a shooting method. Results for the entrenched parameters controlling the flow dynamics have been tabulated and illustrated graphically. The results foundCuO-oil based nanofluid to exhibit higher mass transfer rate and lower heat transfer rate and skin friction coefficient than Al2O3-oil based nanofluid under the same viscoelastic condition. This indicates that CuO-oil based nanofluid can be used as the working fluid in mechanical dampers.

Analytical Study of Magnetohydrodynamic Casson Fluid Flow over an Inclined Non-Linear Stretching Surface with Chemical Reaction in a Forchheimer Porous Medium

This study investigates the steady, two-dimensional boundary layer flow of a Casson fluid over an inclined nonlinear stretching surface embedded within a Forchheimer porous medium. The governing partial differential equations are transformed into a set of ordinary differential equations through similarity transformations. The analysis incorporates the effects of an external uniform magnetic field, gravitational forces, thermal radiation modeled by the Rosseland approximation, and first-order homogeneous chemical reactions. We consider several dimensionless parameters, including the Casson fluid parameter, magnetic parameter, Darcy and Forchheimer numbers, Prandtl and Schmidt numbers, and the Eckert number to characterize the flow, heat, and mass transfer phenomena. Analytical solutions for the velocity, temperature, and concentration profiles are derived under simplifying assumptions, and expressions for critical physical quantities such as the skin friction coefficient, Nusselt number, and Sherwood number are obtained.

Numerical simulation of rotating flow of CNT nanofluids with thermal radiation, ohmic heating, and autocatalytic chemical reactions

The dispersion of carbon nanotubes in conventional fluids provides a variety of applications, using their unique features to develop efficiency, performance, and functionality in many industrial and scientific processes. Some of the applications are energy conversion, fluid stirring, aligned nanocomposites, heat exchangers, electronics cooling, etc. Considering the aforementioned applications, this communication presents a comparative examination of the rotating flow of CNTs past a stretchable sheet with suction and velocity slip. This study is unique because it looks at the non-linear radiative, Darcy–Forchheimer, and rotational flow of CNTs past a stretchable sheet with considering ohmic heating and homogeneous/heterogeneous reactions. These type of issues have not been previously discussed. Suitable conversions are adopted to alter the governing nonlinear PDEs into nonlinear ODEs. The reduced ODEs are numerically reckoned by adopting the bvp4c scheme in MATLAB. The repercussions of flow factors on velocity, temperature, nanoparticle concentration, skin friction coefficients, and local Nusselt number are provided via tables and graphs. It is revealed that the primary velocity profile dwindles when augmenting the values of suction/injection, porosity, rotational, and magnetic field parameters. The temperature ratio and radiation parameters contribute to the thermal profile’s development. The magnetic field parameter and the Forchheimer number play a dual role in both directional skin friction coefficients. The larger values of radiation and temperature ratio parameters improve the heat transfer rate.

Sensitivity analysis of radiative hybrid nanofluid flow across a moving permeable wedge with variable surface temperature and magnetic field effects

PurposeIn the present article, sensitivity analysis was studied in the presence of the combined effects of thermal radiation, suction and magnetohydrodynamics (MHD) effects on a Nimonic 80A-Fe3O4/water hybrid nanofluid across moving a wedge with variable surface temperature and buoyancy effects.Design/methodology/approachThe governing equations were transformed using similarity transformations and solved using MATLAB bvp4c code and response surface methodology (RSM), with quadratic face-centred central composite design being implemented. All results and graphs were formulated after positive outcomes of our results with existing literature.FindingsAn increase in magnetic parameter (M) and velocity ratio parameter (R) resulted in an increase in velocity profiles and local Nusselt number, while a reverse trend was observed for temperature profiles. With radiation parameter Rd = 0.8, the local Nusselt number increased by 4.08% as the velocity ratio parameter increased from R = 0.0 to R = 0.5. The Nusselt number was found to be most sensitive to R, while the latter produced negative sensitivity on skin friction coefficient. The skin friction coefficient for the hybrid nanofluid model increased by 35.39% compared to the regular fluid model, with a very low standard deviation value of 10−4. The Model F-value for Nusselt number model was found to be 939278.49 with a noise ratio of 3618.711. Skin friction coefficient was found to be most sensitive with respect to changes in the parametric values of M.Research limitations/implicationsNimonic 80A being a super-alloy of nickel-iron-chromium and built in high frequency melting, it can work up to 1500°F and is extensively used in automobile exhaust valves.Practical implicationsThe present study finds numerous applications in biotoxicity studies, medical industries, water heaters and the forging of hot exhaust valve heads.Originality/valueIn view of various applications of our present study, there remains a gap in examining the sensitivity analysis of a hybrid nanofluid flow model across a moving permeable wedge using the Tiwari–Das model, which required clinical investigations numerically and statistically.

Analysis of Water Film Distribution and Aerodynamic Performances of High-Speed Train Under Rainfall Environment

The current research on the aerodynamic performance of the train running in rainy weather is primarily concerned with the trajectory of the raindrops and the aerodynamic variation of trains caused by raindrops. In fact, water film will generate on the train body when raindrops hit the train, which interacts with the flow field around the train, and would probably affect the aerodynamic performance of the train. In this paper, based on shear stress transport (SST) k-w turbulence model and Euler-Lagrange discrete phase model, the aerodynamic calculation model of a high-speed train under rainfall environment is established. The LWF (Lagrangian wall film) is used to simulate the water film distribution of the high-speed train under different rainfall intensities, and the aerodynamic performance of the train are studied. The calculation results show that raindrops will gather on the train surface and form water film under rainfall environment. With the extension of rainfall time, the thickness and coverage range of water film expand, and the maximum thickness of water film can reach 4.95 mm under the working conditions in this paper. The average thickness of water film on the train body increases with the rainfall intensity. When the rainfall intensity increases from 100 mm/h to 500 mm/h, the average water film thickness will increase by 3.26 times. The velocity of water film in the streamlined area of head car is larger than that in other areas, and the maximum velocity is 22.14 m/s. Compared with the rainless environment condition, the skin friction coefficient of the high-speed train increases and the average value will increase by 10.74% for a rainfall intensity of 500 mm/h. The positive pressure and resistance coefficient of the head car increase with the rainfall intensity. This research proposes a methodology to systematically analyze the generation of water film on the train surface and its influence on the train aerodynamic performance; the analysis can provide more practical results and can serve as a reference basis for the design and development of high-speed trains.

Deep Reinforcement Learning for the Management of the Wall Regeneration Cycle in Wall-Bounded Turbulent Flows

AbstractThe wall cycle in wall-bounded turbulent flows is a complex turbulence regeneration mechanism that remains not fully understood. This study explores the potential of deep reinforcement learning (DRL) for managing the wall regeneration cycle to achieve desired flow dynamics. To create a robust framework for DRL-based flow control, we have integrated the StableBaselines3 DRL libraries with the open-source direct numerical simulation (DNS) solver CaNS. The DRL agent interacts with the DNS environment, learning policies that modify wall boundary conditions to optimise objectives such as the reduction of the skin-friction coefficient or the enhancement of certain coherent structures’ features. The implementation makes use of the message-passing-interface (MPI) wrappers for efficient communication between the Python-based DRL agent and the DNS solver, ensuring scalability on high-performance computing architectures. Initial experiments demonstrate the capability of DRL to achieve drag reduction rates comparable with those achieved via traditional methods, although limited to short time intervals. We also propose a strategy to enhance the coherence of velocity streaks, assuming that maintaining straight streaks can inhibit instability and further reduce skin-friction. Our results highlight the promise of DRL in flow-control applications and underscore the need for more advanced control laws and objective functions. Future work will focus on optimising actuation intervals and exploring new computational architectures to extend the applicability and the efficiency of DRL in turbulent flow management.

Artificial intelligence neural network and fuzzy modelling of unsteady Sisko trihybrid nanofluids for cancer therapy with entropy insights

The main objective of the current endeavor is to monitor hypothetical processes utilizing a Sisko tri-hybrid fluid over a rotating disk with entropy generation suspended in Darcy-Forchheimer porous medium. Electro Magneto Hydro Dynamics (EMHD), non-linear thermal radiation and exponential and thermal- space dependent heat source/sink coefficients are considered with the intent of conceiving an Runge-Kutta-Fehlberg method with shooting procedures integrated with a combination of an Adaptive Neuro-Fuzzy Inference System (ANFIS) and Reptile Search Algorithm (RSA). Then, ANFIS-RSA, is used to predict the Nusselt number, skin friction co-efficient in radial and tangential velocities. Reliable self-similarity variables have reduced a non-linear partial differential set of equations into an ordinary differential equation. According to the empirical evidence, Sisko fluid parameter rises the radial velocity whereas for magnetic field and Darcy-Forchheimer the azimuthal and axial velocities visualizations decreasing trend, respectively. The entropy generation and Bejan number rises for electric and radiation effects. Also, ANFIS-RSA indicates that the model attained a high level of precision in terms of radial velocity (98.13%), tangential velocity (98.18%) and Nusselt number (98.91%). Thus, the longer rendering of the nanoparticles used here might, makes them potentially helpful for regulating the therapeutic impact in the management and treatment of cancer.

Transient convective heat transfer analysis in dull cornered triangular enclosure with open-cell metal foam and hybrid nano fluid

Transient convective heat transfer is a type of heat transfer that occurs when fluid convection changes in temperature, heat flux, or velocity over time. However, the heat transfer phenomenon in porous media under transient situations has not been extensively examined in current research, and only a few studies have focused on triangle enclosures. Thus, a novel Dull Cornered Triangular Enclosure with Bottom separated Open-Cell Aluminum Metal Foam and Hybrid Nano Fluid is introduced. Neglecting viscous dissipation and thermal dispersion in porous media in the prevailing studies leads to underestimated temperature rises. Hence, a novel DMW-GO-MWCNT nanofluid is used as a coolant, featuring 2% graphene oxide (GO) and multi-walled carbon nanotubes (MWCNTs), enhancing convective heat transmission. Including viscous dissipation and thermal dispersion in transient simulations accurately models temperature rises, avoiding suboptimal designs. The sharp lower corners in traditional triangle enclosures create stagnation points, disrupting uniform heating or cooling and reducing heat transfer efficiency. Thus, a Dull Cornered Triangular Enclosure is designed to eliminate recirculation zones by rounding the bottom corners, improving heat transfer efficiency. The placement of porous media in contact with heating surface enclosures hinders transient convective heat transfer, leading to dominant conductive heat transfer, increased cavitation risk, reduced Nusselt number, and impaired overall convective heat transfer efficiency. Therefore, incorporating Bottom Separated Open-Cell Aluminum Metal Foam in the proposed triangular enclosure lowers pressure drop and increases the Nusselt number with increased convective heat transfer efficiency. The results show that the proposed model has improved the overall transient convective heat transfer performance with a high Nusselt number, thermal conductivity, thermal expansion coefficient, effectiveness, heat transfer coefficient, heat transfer rate; and low deviation time, skin friction coefficient, and pressure drop.

Construction of optimised theoretical model using ANOVA -Taguchi methodology for transient flow of Carreau nanofluid through microchannel prone to radiation

The current study intends to predict the optimised condition to attain the objective of acquiring highest heat transfer rate to develop an efficient model. The transient flow of Carreau nanofluid within a microchannel when channel walls are susceptible to radiation is contemplated. Buongiorno model is employed, which emphasizes the repercussions of Brownian motion and thermophoresis phenomena; also, mixed-convective flow is accounted. The modelled problem gives rise to partial differential equations, which are non-dimensionalized employing non-dimensional quantities. The resultant equations are solved numerically using the finite difference method. Results of analysis demonstrate that the Weissenberg number for n<1 depicts shear thinning nature, and for n>1, depicts shear thickening nature, decreasing velocity. The skin friction coefficient increases when solutal Grashof number rises for the high range of the Reynolds number. The Sherwood number increases when Schmidt number is less for increased value of Reynolds number. Optimization method reveals the highest heat transfer rate of 7.3687 for the considered model. ANOVA results show that the manipulation of Reynolds number is crucial with 57.29% impact and the manipulation of Prandtl number has minor impact of 1.41%on Nusselt number. Shear thinning nature of Carreau fluid finds its application in extrudability, printability and injectability and shear thickening nature is extensively used in industrial polishing, explosion resistance.

Heat transport analysis of three-dimensional magnetohydrodynamics nanofluid flow through an extending sheet with thermal radiation and heat source/sink

Regarding heat transformation efficiency, the hybrid nanofluid performs superior to the nanofluid. The majority of hybrid nanofluid uses are in the industrial sector, producing solar energy, cooling generators, and vehicle heat transformation. Heat transfer and nanofluid velocity are the two most crucial transport properties that must be evaluated before the first and second thermodynamics equations are applied to nanoscale fluids. The objective of this work is to investigate the characteristics of transmission of heat of magnetohydrodynamic (MHD) nanofluid (Ag/H2O)and hybrid nanofluid (Ag+Al2O3/H2O)flow on a linear extensible sheet when magnetic forces are present. Similarity variables are applied to transform a set of nonlinear dimensionless partial-differential equations to collection of ordinary-differential equations. The non-analytical solutions of these transformed equations are found utilizing the MATLAB mathematical program's bvp4c function. The impression of various physical attributes along skin friction coefficients and properties of heat transmission are analyzed. The behavior of key parameters, including surface stretching ratio, rotational and magnetic effects, for temperature and velocity, is shown using graphs and tables. In conclusion, hybrid nanofluids, which comprise silver and aluminum oxide nanoparticles dispersed in water, outperform silver-water nanofluids by around 10–15 % under magnetohydrodynamic (MHD). The higher thermal conductivity of these hybrid nanofluids allows for better heat dissipation, making them an appealing option for applications that need optimal thermal management in the presence of magnetic fields.