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A finite element based numerical model is employed to obtain isothermal and heat transfer predictions for the case of turbulent flow with a decaying swirl component in a stationary circular pipe. An assessment is made on the quality of predictions based on the choice of turbulence modelling technique adopted to close the governing equations. In the present work the one‐equation, two‐equation and algebraic Reynolds stress turbulence models are employed. For the confined flow problem investigated, accurate prediction of the near‐wall conditions is essential. This is particularly the case for confined swirling flow where the variation of variables near the wall is often somewhat greater than encountered in pure axial flow. A finite element based near‐wall model is employed as an alternative to conventional techniques such as the use of the standard logarithmic functions. Of significance is the fact that flow predictions based on the use of the unidimensional finite element techniques are closer to experiment compared to the wall function based solutions for a given turbulence model. As expected, improvements in the flow predictions directly contribute to improved simulation of the thermal aspects of the problem.

A computational methodology, based on the coupling of the finite element and boundary element methods, is developed for the solution of magnetothermal problems. The finite element formulation and boundary element formulation, along with their coupling, are discussed. The coupling procedure is also presented, which entails the application of the LU decomposition to eliminate the need for the direct inversion of matrices resulting from FE‐BE formulation, thereby saving computation time and storage space. Corners for both FE‐BE interface and BE regions, where discontinuous fluxes exist, are treated using the double flux concept. Numerical results are presented for three different systems and compared with analytical solutions when available. Numerical experiments suggest that for magnetothermal problems involving small skin depths, a careful mesh distribution is critical for accurate prediction of the field variables of interest. It is found that the accuracy of the temperature distribution is strongly dependent upon that of the magnetic vector potential. A small error in the magnetic vector potential can produce significant errors in the subsequent temperature calculations. Thus, particular attention must be paid to the design of a suitable mesh for the accurate prediction of vector potentials. From all the cases examined, 4‐node linear elements with adequate progressive coarsening of meshes from the surface gave the results with best accuracy.

One of the most challenging aspects in the health care industry is to understand the nuances and strategies of those companies that provide both B2B and B2C services, apart from being supported by their management team, quality officers, the HR Manager, the clinicians, the doctors, and the holistic support of all staff. This case study focusses on analyzing the various indicators of success of The Health Medical Services (THMS), a major service provider in the health care sector, serving both B2B and B2C markets in the UAE and the organizational factors that drove the service provider to success, creating an exceptional experience for both their internal and external customers. The unique success drivers of THMS, as brought out by the current study include Customer Relationship Management, unique leadership style, employee engagement, market orientation, Quality Circles, patient-centric care, and service innovation in health care that supports their sustainability and scalability. Moreover, a literature review on the success drivers brings out the academic implications of the study.

This study aims to investigate the thermal performance enhancements of phase change materials (PCMs) through the integration of extended fins and CuO nanoparticles under the impact of solar irradiation. The research focuses on improving the melting behavior and thermal efficiency of PCM-based energy storage systems to facilitate the design of more efficient energy storage solutions.

The analysis is conducted on a top-heated rectangular thermal system filled with pure PCM and nanoparticle-enhanced PCM (NePCM) mixed with 0.01% Wt. CuO nanoparticles, with varying fin configurations considering PCM volume and surface area of fins constraint. The shape of the fin is modified from single to multiple numbers, maintaining the same surface area. The analysis is carried out both experimentally and numerically for the without fin case, and the study is extended numerically (utilizing the finite volume method) considering different sizes and positions of the fins. The study evaluates the impact of nanoparticle inclusion, fin geometry variations and the thermal performance of three different types of PCM (lauric acid, RT-35HC and P-58). Numerical results are validated against the in-house experimental results.

The study successfully validates the numerical simulations with experimental data, enhancing the credibility of the findings for real-world applications. The addition of 0.01% Wt. CuO nanoparticles to PCM resulted in a 16.36% enhancement in energy storage, as observed experimentally, whereas the numerical simulation showed an 8.55% increase. The inclusion of CuO nanoparticles accelerated the melting process across all fin configurations, with a notable enhancement parameter of 16.51% for the single fin arrangement. The introduction of a single fin structure increased the energy storage rate, but further additions of fins led to diminishing returns, with a maximum energy storage rate of 35.19 J/min achieved with CuO-enhanced PCM in the presence of single fin. The study also highlights RT-35HC as the most effective PCM, offering the highest energy storage and fastest melting speed, making it ideal for rapid thermal response applications.

Future research could explore different types and concentrations of nanoparticles as well as a broader range of fin geometries and materials to further enhance the performance of PCM-based energy storage systems. Long-term experimental validation under real-world conditions would also enhance the applicability and reliability of the findings.

This study provides valuable insights into optimizing thermal energy storage systems by combining nanoparticle enhancement and fin geometry optimization. The results offer practical guidance for improving the efficiency and effectiveness of PCM-based energy storage units in various applications.

There are industrial applications for varying speed lid-driven flow and heat transfer such as the float glass process where the glass film stretches or thickens depending on the desired thickness. Hence the tin cavity underneath or the nitrogen cavity above is being driven by a variable speed. The purpose of this paper is to simulate such behavior.

Numerical solution of variable speed lid-driven cavity is carried out with thermal radiation being considered using control volume approach and staggered grid and applying the SIMPLE algorithm. Transient simulation is used for 2D model in the present study. Second order upwind schemes were used for discretization of momentum, energy equations and time.

Under laminar conditions, thermal radiation plays a significant role in the heat transfer characteristics of the lid-driven cavity. This effect is more significant for blackbody radiation and decreases as the surface emissivity decreases. Nusselt number (Nu) behavior lies between these two limiting case profiles considering constant speed profiles of both maximum and minimum lid velocities, respectively. In addition, local Nu values at the tip where higher than those at the top of the cavity that is stagnant.

The study is limited to laminar flow case.

The applications of this study can be found in float glass process where the glass film stretches or thickens depending on the desired thickness. Hence the tin cavity underneath or the nitrogen cavity above is being driven by a variable speed. Another application involves casting of plastic films. The molten polymer leaves the die with a considerable thickness and high temperature. The film is then trenched to reach its final thickness. In this case, usually there is no actual cavity above or below the film but one can approximate the problem as such. Other similar applications do exist in food drying and processing where the conveyer belt is in portions and their speed may not be the same in different section of the processing oven.

To the best of the authors knowledge, no study in the literature addressed the effect of thermal radiation in lid-driven cavities with variable speed

Numerical study of nanofluid forced convection within a branching channel was performed under the influence of a uniform magnetic field. The purpose of this study is to enhance the heat transfer performance of the separated flow at the branching channel with the use of magnetic field and nanofluid. The use of magnetic field and enhancement in both the thermal conductivity and electrical conductivity with the inclusion of the nanoparticles provides favorable thermophysical properties of the nanofluid when it used as a heat transfer fluid in a branching channel. The results of this study may be used to control the thermal performance in a branching channel and further optimization studies in the presence of magnetic field.

Galerkin weighted residual finite element method was used for the simulations. The numerical simulation results are performed by changing the inclination angle of the lower branching channel (between 0° and 90°), thermophysical properties of the fluid via inclusion of nanoparticles (between 0 and 0.04), Reynolds number (between 100 and 400) and magnetic field strength (Hartmann number changes between 0 and 15).

It was observed that the recirculation zones and reattachment length of the upper and lower branching channels are affected by the variation of those parameters. Reattachment lengths increase with the augmentation of the Reynolds number and deterioration of the Hartmann number. Average Nusselt number becomes higher for higher values of Hartmann number and solid particle volume fraction. Inclusion of the nanoparticle to the base fluid is very effective for the configuration with higher values of Hartmann number. An optimum value of the inclination angle of the lower branching channel is observed, beyond which heat transfer rate is significantly reduced due to the establishment of a large vortex in the upper branching channel and restriction of the fluid motion.

In this study, forced convection of nanofluid flow in a branching channel under the effect of magnetic field was numerically studied. Magnetic field effects with nanoparticle inclusion to the base fluid on the convective heat transfer was analyzed for various inclination angles of the lower branching channel. Flow separation at the junction of the channels and thus convective heat transfer rate are influenced by the variation of these parameters. There are many studies related to application of the magnetic field with nanofluids, and a few of them are related to configurations with separated flows. To the best of the authors’ knowledge, there exist no studies for the application of nanofluids and magnetic field for the convective heat transfer in a branching channel. This topic is of importance as there are many engineering applications of the branching channels.

Fabrics with photothermal conversion functions were developed based on the introduction of shape stable composite phase change materials (CPCMs).

Acidified single-walled carbon nanotubes (SWCNTs) were selected as support material to prepare CPCMs with n-octadecane to improve the thermal conductivity and shape stability. The CPCMs were finished onto the surface of cotton fabric through the coating and screen-printing method. The chemical properties of CPCMs were characterized by Fourier transform infrared spectrometer, XRD and differential scanning calorimetry (DSC). The shape stability and thermal conductivity were also evaluated. In addition, the photothermal conversion and temperature-regulating performance of the finished fabrics were analyzed.

When the addition amount of acidified SWCNTs are 14% to the mass of n-octadecane, the best shape stability of CPCMs is obtained. DSC analysis shows that the latent heat energy storage of CPCMs is as high as 183.1 J/g. The thermal conductivity is increased by 84.4% compared with that of n-octadecane. The temperature-regulating fabrics coated with CPCMs have good photothermal conversion properties.

CPCMs with high latent heat properties are applied to the fabric surface through screen printing technology, which not only gives the fabric the photothermal conversion performance but also reflects the design of personalized patterns.

CPCMs and polydimethylsiloxane (PDMS) are mixed to make printing paste and printed cotton fabric with temperature-regulating functional is developed.

SWCNTs and n-octadecane are composited to prepare CPCMs with excellent thermal properties, which can be mixed with PDMS to make printing paste without adding other pastes. The fabric is screen-printed to obtain a personalized pattern and can be given a thermoregulatory function.

Unsteady simulation of forced convection of two heated horizontal cylinders confined in a 2D squared enclosure. The paper aims to discuss this issue.

The finite-volume method is used to solve the transient heat transfer problem by employing quadrilateral mesh type. To solve the governing equations (conservations of mass, momentum and energy) on unstructured control volumes, a second-order quadratic upwind interpolation of convective kinematics scheme for the convection terms and the semi-implicit method for pressure-linked equations pressure correction algorithm were used.

The results indicate that the variation of the area-averaged Nusselt number strongly depends on the Reynolds number. On the contrary, the effect of cylinders’ space on heat transfer was found to be nearly negligible for Re < 460. It is also observed that steady state flow and heat transfer shift to periodical oscillation, and ultimately chaotic oscillation in non-dimensional cylinders distance of 0.1; however the sequence of appearing this route is completely different for higher cylinder spaces.

Reynolds numbers between 380 and 550 and dimensionless horizontal distances of cylinders 0.1, 0.2 and 0.3.

Comprehensive knowledge of the effect of tube arrays flow regime on each other and in turn, heat transfer among them. Better understanding of convective heat transfer around an array of horizontal cylinders compared with from those around a single cylinder because of the mutual interaction of the buoyant plumes generated by the cylinders. Time-dependent phenomena of the problem including periodical oscillation or chaotic features.

The purpose of this paper is to investigate the effect of pulsed magnetic field (PMF) with different duty cycles on the melt flow and heat transfer behaviors during direct-chill (DC) casting of large-size magnesium alloy billet and find the appropriate range of duty cycle.

A transient two-dimensional mathematical model coupled electromagnetic field, flow field and thermal field, is conducted to study the melt flow and temperature field under PMF and compared with that under the harmonic magnetic field.

The results reveal that melt vibration and fluctuation are generated due to the instantaneous impact of repeated thrust and pull effects of Lorentz force under PMF. The peak of Lorentz force decreases greatly with the increasing duty cycle, but the melt fluctuation region is expanded with higher duty cycle, which accelerates the interior melt velocity and reduces the temperature gradient at the liquid-solid interface. However, PMF with overly high duty cycle has adverse effect on the melt convection and limited influence on the interior melt. A duty cycle of 20% to 50% is a reasonable range.

This paper can provide guiding significance for the setting of duty cycle parameters on DC casting under PMF.

There are few reports on the effect of PMF parameters during DC casting with applying PMF, especially for duty cycle, a parameter unique to PMF. The findings will be helpful for applying the external field of PMF on DC casting.

The aim of this study is to apply an enthalpy-based lattice Boltzmann method with multi distribution function model, to investigate melting process with natural convection inside a cavity with an obstacle. The cavity is filled with water (ice)-based nanofluid containing copper nanoparticles.

This methodology eliminates the requirement of satisfying conditions at the phase change front. The combination of lattice D2Q9 and D2Q5 models is implemented to determine the density, velocity and temperature fields. The simulations are carried out for Rayleigh number of 105, various volume fractions of the nanoparticles and various positions of the cubic obstacle.

The predicated results demonstrate that the use of nanoparticles leads to enhancement of thermal conductivity of nano-enhanced phase change materials in comparison with conventional PCMs. When the position of the obstacle changes from the top to the bottom of the cavity the melting rate increases 75 percent. The numerical study indicates that by increasing the solid concentration from 0 to 0.04, the heat release enhances 52.7, 41.2 and 30 percent when the obstacle is located on the top, middle and bottom sections of the cavity, respectively. It is also observed that, the employment of nanoparticles is more effective when the heat conduction dominates.

The main unacceptable property of most PCMs is their low thermal conductivity, and hence, heat transfer enhancement using nanofluid will be useful for thermal energy storage applications.