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The purpose of this study is to examine the melting heat transfer of magnetohydrodynamics Casson nanofluid flow with viscous dissipation, radiation, and complete slip effects on a porous stretching sheet. Since, the study of melting heat transfer has mesmerized the attention of scientists and engineers in the sense of its enormous uses in industrial processes, solidification, casting, and technology.

Bejan number and entropy are analyzed. Exploration of irreversibility is modeled using the thermodynamics second law. There is a discussion on thermophoresis and Brownian diffusion along with first-order chemical reactions. Adequate transformations are introduced to convert the controlling partial differential equations to ordinary differential equations. The three-phase Lobatto solvers (bvp5c) are used to obtain numerical solutions of the transmitted equations.

The effects of various factors on temperature, velocity, concentration, Bejan number and entropy rate are shown graphically. The velocity field is enhanced by increasing the melting heat parameter, and it declines for growing magnetic parameters. Temperature is decreased for increasing parametric values of melting heat, porous and Casson parameters. A 7% decrease in the Sherwood distribution is seen when we increase the Brownian motion parameter from 0.1 to 0.2. Similarly, an 11% decrement is found in the Nusselt distribution for increasing the Brinkman number from 0.5 to 1.

Entropy and Bejan number experience dual tendencies whenever the melting heat parameter increases. Nusselt number and skin friction experience the opposite behavior for the increasing values of melting parameter. Sherwood number decreases for the increasing values of melting parameter. The velocity profile is directly related to the melting parameter and inversely related to porous and magnetic parameters. Thermophoresis and Brinkman parameters boost the temperature profile and it is controlled by melting and porous parameters. Some notable fields where the present study is used inevitably are silicon wafering, geothermal energy recovery and semiconductor manufacturing.

The sustainable development of contractor organizations depends highly on bidding decision-making of projects. This current study, leveraging the risk decision-making theory, attempts to elucidate the process of contractors’ bid/no-bid decision-making and reveal how the process is influenced by their perception of risk. In particular, this study aims to explore the multiple mediating effects of contractors’ trust in owners and risk perception in explaining the relationship between contractual governance outlined in owners’ bidding documents and the bid/no-bid decisions.

A questionnaire survey was used to obtain data from the Chinese construction industry. The PLS-SEM technique was employed to analyze a dataset of 557 available questionnaires.

The findings indicate that (1) the contractual governance provided by owners’ bidding documents positively impacts contractors’ bid/no-bid decisions; (2) both risk perception and trust serve as multiple mediators in this relationship and (3) trust mediates the relationship between contractual governance and contractors’ risk perception.

Drawing upon the risk decision-making theory, this study proposes a multiple mediation model for understanding contractors’ bid/no-bid decision-making processes. It contributes to a better understanding of contractors’ bidding decision-making mechanisms, thereby offering theoretical guidance for contractors to make reasonable and informed risk decisions.

Insufficient time allocation for the bidding period occurs, causing drawbacks to both parties, the client and the bidder. Hence, this study aims to evaluate the time allocated for preparing a bid proposal as per the National Competitive Bidding (NCB) in the Sri Lankan context.

The study has adopted a mixed method approach and expert interviews and document review to detect, analyse and validate the issues, and solutions based on NCB along with the adequacy of the allocated bidding period used as main data collection tools. Both qualitative and quantitative data were analysed through manual content analysis and inferential analysis respectively.

Overall, 24 local issues with the existing competitive bidding process and solutions for each were identified. Among the 24 local issues, it was unanimously agreed by all interviewees that three specific issues require attention and improvement. These issues are related to the standard and incompleteness of bidding documents, inaccurate BOQ quantities measured by the consultant or the main contractor, and the excessive number of bidding document amendments by the consultant. It was revealed that a maximum of 42 calendar days (6 weeks) is sufficient for the bidding process while a minimum of 21 calendar days (3 weeks) is insufficient.

The findings of this study would be recommended that Information and Communication Technology Agency (ICTA) understand the necessity of revising the NCB reference to the time allocated for the preparation of bids. By recognising the importance of sufficient time allocation for bid preparation, this research serves as a practical guide for authorities involved in policy formulation, aiding them in implementing revisions that align with the dynamic requirements of bidding procedures.

Nanofluids enhance heat transfer due to the inclusion of nanoparticles, but the exact reasons remain debated. Limited nanoscale experiments hinder understanding. To investigate the thermal effects of nanoparticles, understanding nanoparticle aggregation kinetics is crucial. Nanoparticles have applications in various industrial fields. This study compares the effects of nanoparticle aggregation and non-aggregation in a nanofluid flow influenced by an inclined magnetic field around an expanding or shrinking cylinder, incorporating the generalized Fourier law with a prescribed surface temperature.

The model problem is solved numerically with the bvp4c finite difference collocation method, known for its accuracy.

Graphs and tables illustrate how key factors affect velocity and thermal fields. The results revealed that for stretching flows, fluid velocity increases with higher nanoparticle concentrations and velocity slip, while shrinking flows show opposite trends. The drag force decreases with rising Hartmann numbers and nanoparticle volume fraction, irrespective of aggregation. Surface drag is more affected by aggregation than non-aggregation in both shrinking and expanding cases. The study also validates the proposed model.

Before this, numerous attempts discussed aggregation and non-aggregation separately on a deforming cylinder. Nevertheless, no study has yet assessed the impact of a slanted magnetic field on comparing the effects of nanoparticle aggregation versus non-aggregation in nanoliquid flow over a deformable or shrinking cylinder. This seems to be the first attempt to compare nanoparticle aggregation versus non-aggregation in nanoliquid flow.

The purpose of this study is to consider the dynamics of Casson–Walters-B alongside gyrotactic microorganisms through the investigation of antibacterial and antiviral mechanisms using silver nanoparticles (AgNPs). The Casson fluid and Walters-B flow from the penetrable plate to the boundary layer (BL) in this analysis. The antiviral and antibacterial mechanisms of AgNPs were separately examined in this study.

The physical phenomenon of this problem was analyzed with partial differential equations (PDEs). These PDEs were changed into ordinary differential equations (ODEs) to further explain the significance of pertinent control parameters. The set of equations is solved numerically by implementing the spectral relaxation method (SRM). SRM is a numerical technique that uses the basic techniques of Gauss-Seidel. The SRM first decouples and linearizes the coupled nonlinear set of ODEs.

In this finding, it is found that the thermal radiation parameter produces higher temperatures within the BL to cause blockage in viral replications. It is found in this study that the magnetic parameter assisted in disinfection by lowering the antiviral and antibacterial mechanisms within the momentum BL. This is evident from the reduction in the velocity and momentum BL as the Casson and Walters-B parameters increase.

This paper is unique because it examined the antiviral and antibacterial mechanisms by using AgNPs. Prior to the authors’ understanding, no study of this type was conducted in the past. To the best of the authors’ knowledge, no other study in the past has examined the mechanisms of antiviral and antibacterial separately within the BL. Also, the simultaneous flow of Casson (honey) and Walters-B fluids were considered flowing through the vertical porous plate to the BL.

Flow induced by rotating disks is of great practical importance in several engineering applications such as rotating heat exchangers, turbine disks, pumps and many more. The present research has been freshly displayed regarding the implementation of an engine oil-based Casson tri-hybrid nanofluid across a rotating disk in mass and heat transferal developments. The purpose of this study is to contemplate the attributes of the flowing tri-hybrid nanofluid by incorporating porosity effects and magnetization and velocity slip effects, viscous dissipation, radiating flux, temperature slip, chemical reaction and activation energy.

The articulated fluid flow is described by a set of partial differential equations which are converted into one set of higher-order ordinary differential equations (ODEs) by using convenient conversions. The numerical solution of this transformed set of ODEs has been spearheaded by using the effectual bvp4c scheme.

The acquired results show that the heat transmission rate for the Casson tri-hybrid nanofluid is intensified by, respectively, 9.54% and 11.93% when compared to the Casson hybrid nanofluid and Casson nanofluid. Also, the mass transmission rate for the Casson tri-hybrid nanofluid is augmented by 1.09% and 2.14%, respectively, when compared to the Casson hybrid nanofluid and Casson nanofluid.

The current investigation presents an educative response on how the flow profiles vary with changes in the inevitable flow parameters. As per authors’ knowledge, no such scrutinization has been carried out previously; therefore, our results are novel and unique.

The purpose of the study is to explore the three-dimensional heat and mass transport dynamics of the magneto-hydrodynamic non-Newtonian (Casson fluid) hybrid nanofluid flow comprised of − as nanoparticles suspended in base liquid water as it passes through a flexible spinning disc. The influence of a magnetic field, rotation parameter, porosity, Darcy−Forchheimer, Arrhenius’s activation energy, chemical reaction, Schmidt number and nanoparticle shape effects are substantial physical features of the investigation. Furthermore, the influence of hybrid nanofluid on Brownian motion and thermophoresis features has been represented using the Buongiorno model. The novelty of the work is intended to contribute to a better understanding of Casson non-Newtonian fluid boundary layer flow.

The governing mathematical equations that explain the flow and heat and mass transport phenomena for fluid domains include the Navier−Stokes equation, the thermal energy equation and the solutal concentration equations. The governing equations are expressed as partial differential equations, which are then converted into a suitable set of non-linear ordinary differential equations by using the necessary similarity variables. The ordinary differential equations are computed by combining the shooting operation with the three-stage Lobatto BVP4c technique.

Graphs and tables are used in the process of analysing the characteristics of velocity distributions, temperature profiles and solutal curves at varying values of the parameters, along with friction drag, heat transfer rate and Sherwood number. It has been revealed that the radial and axial velocities decrease when the Casson parameter value increases and that the rate of heat transmission is higher in hybrid nanofluids with nanoparticles in the shape of a blade. The increase in Brownian motion and thermophoresis parameters causes a rise in the temperature profile. Also, an increase in the activation energy parameter improves the solutal curve. The use of nanoparticles was shown to improve extrusion properties, the rotary heat process and biofuel generation.

All results are presented graphically and all physical quantities are computed and tabulated. The current results are compared to previous investigations and found to agree significantly with them.

Hybrid nanofluids have remarkable characteristics for improving the process of heat transfer. The findings suggest hybrid nanofluids are beneficial heat transfer fluids for industrial uses. Therefore, this article aims to investigate the Darcy–Forchheimer flow of Zn-TiO_2/H2O hybrid nanofluids through a vertically porous shrinking cylinder.

The thermal transportation phenomenon of radiated hybrid nanomaterials is studied subject to linear thermal radiation and chemical species with the consequence of non-uniform heat source/sink influence. The controlling flow and energy equations in the form of governing hybrid nanofluids are developed and then converted into ODEs by operating appropriate resemblance variables. Using the impacts of controlling parameters, the behaviors of flow constraints are interpreted graphically.

The current study’s outcomes reveal that the water-based hybrid nanomaterials show a promising upsurge in heat transfer rate. Similarly, as the mass transfer rate grows, the drag coefficient and energy transfer rate boost, while due to curvature relations, it tends to diminish for drag friction. In an upper branch solution, the flow field is improved by greater porosity parameter values, whereas in a lower branch solution, it deteriorates. Furthermore, the velocity profile depicts the opposite trend for upper and lower branches due to a boost in the mixed convection parameter.

In light of already conducted studies, the relation of internal heat source varying regarding thermal and space in the rheology of hybrid TiO₂-Zn/H_2O nanofluid possesses intriguing utilization in energy production strategies due to the exhibition of extensive heat energy. The most typical examples of this phenomenon can be observed in nuclear and chemical-reactor power stations, solar power plants for heating and cooling systems, combustion analysis equipment and so on. The current study is devoted to predicting the effect of a varied heat source on the thermal energy characteristics of mixed convective hybrid TiO_2-Zn/H2O nanofluid flow through the vertical cylinder.

Surface properties (smooth or roughness) play a critical role in controlling the wettability, surface area and other physical and chemical properties like fluid flow behaviour over the rough and smooth surfaces. It is reported that rough surfaces are offering more significant insights as compared to smooth surfaces. The purpose of this study is to examine the effects of surface roughness in the diverging channel on physiological fluid flows.

A mathematical formulation based on the conservation of mass and momentum equations is developed to derive exact solutions for the physical quantities under the assumption of low Reynolds numbers and long wavelengths, which are appropriate for biological transport scenarios.

The results reveal that an increase in surface roughness reduces axial velocity and volumetric flow rate while increasing pressure distribution and turbulence in skin friction.

These findings offer valuable insights for biological flow analysis, highlighting the effects of surface roughness, non-uniformity of the channel and magnetic fields.

These findings are very much applicable for designing the pumping devices for transportation of the fluids in non-uniform channels.

This study examines the impact of surface roughness on the peristaltic pumping of viscoelastic (Jeffrey) fluids in diverging channels with transverse magnetic fields.

This study aims to explore the collective influence of several factors, namely, thermal radiation, Brownian motion, magnetic field and variable viscosity parameter, on the boundary layer flow, heat and mass transfer of an electrically steering nanofluid over a radially stretching exterior subjected to convective heating. In addition, the impacts of thermal and solutal buoyancy forces and activation energy are taken into account. The enlarging velocity is assumed to vary linearly with radial distance.

Through the similarity transformation technique, the governing highly nonlinear partial differential equations are transformed into a set of nonlinear ordinary differential equations, which are then numerically solved using the Runge–Kutta–Fehlberg method with a shooting technique.

Graphical depictions are provided to analyze the velocity, temperature and nanoparticle concentration fields under the influence of various pertinent parameters. Furthermore, local skin friction, local Nusselt and Sherwood numbers are quantitatively presented and discussed. A comparison with previous results demonstrates good agreement.

This study uniquely integrates multiple factors influencing boundary layer flow in electrically conducting nanofluids, offering a nuanced understanding of heat and mass transfer over radially stretching surfaces. By using advanced numerical methods, it provides valuable insights and quantitative data that can inform practical applications in engineering and materials science.