bluuebunny/crossref_metadata_2025_split huggingface dataset:
Application of adjustment calculus to the Trefftz method for calculating temperature field of the boiling liquid flowing in a minichannel
Authors: Hożejowska Sylwia , Kaniowski Robert , E. Poniewski Mieczysùaw 
Published: April 2014

Purpose
– The purpose of this paper is to focus on the application of the Trefftz method to the calculation of the two-dimensional (2D) temperature field in the boiling refrigerant flow through an asymmetrically heated vertical minichannel with a rectangular cross-section. The considerations were limited to determining the temperature of the continuous phase – liquid for bubbly and bubbly-slug flow. The numerical solution found with the Trefftz methods was compared with the simplified solution. For nucleate boiling, heat transfer coefficient at the heating foil – liquid contact was determined.

Design/methodology/approach
– The Trefftz method was used to determine 2D temperature distributions for the glass pane, the heating foil and the boiling liquid. The temperature fields were approximated by the sum of the particular solution and the linear combination of suitable Trefftz functions. Coefficients of linear combination were computed using experimental data, including heating foil temperature measurements obtained with the liquid-crystal method and experimentally determined void fraction. The computations were based on the Trefftz method supplemented with the adjustment calculus.

Findings
– The way of solving direct and inverse problems of heat conduction in solid bodies (isolating glass, heating foil) and in liquids (boiling refrigerant flowing through the minichannel) was presented. For the first time, both 2D temperature fields for the heating foil and the boiling liquid were calculated while simultaneously using the Trefftz method. The known temperature values of the foil and liquid allowed the calculation of the heat transfer coefficient and the heat flux at the heating foil-liquid contact. Adjustment calculus implemented into the Trefftz method was used to smooth the measurement data and to reduce their errors.

Practical implications
– The approach proposed in the paper can be applied to determining 2D temperature field, heat flux and heat transfer coefficient in direct and inverse problems concerning two-phase flowing miniature compact heat exchangers.

Originality/value
– The paper presents a novel implementation of the Trefftz method to simultaneous solving an inverse problem in the heating foil and the contacting flowing liquid.
Large eddy simulation of a fully developed non-isothermal turbulent channel flow
Authors: Jaszczur Marek 
Published: April 2014

Purpose– The purpose of this paper is to numerically study heated channel flow using direct numerical simulation (DNS) and large eddy simulation (LES) method. Using different domain size and different grid resolution it is show that filtering procedure is influenced and may results in very different solutions.Design/methodology/approach– Turbulent non-isothermal fully developed channel flow has been investigated using LES. The filtered Navier-stokes and energy equations were numerically solved with dynamic subgrid scale (SGS) model, standard Smagorinsky model or without additional model for the turbulent SGS stress and heat flux required to close the governing equations.Findings– The numerical LES results in comparison with the DNS data demonstrate that the LES computations may not always offers a reliable prediction of non-isothermal turbulent flow in open channel. It has been found that, even though the models reproduces accurately results for the flow field the thermal field computed using LES do not necessary match the DNS results. Introducing SGS model for scalar do not always show large improvement. One of the reason is thickness of hydrodynamic and thermal boundary layer. In the cases when boundary layers are very different it is not easy optimally set up control volumes in the domain.Originality/value– This is one of the first instance in which a results of numerical computations for different grid resolution, different stretching, SGS model is employed for non-isothermal turbulent channel flow. It shows that in the cases when boundary layers hydrodynamic and thermal are very different it is hardly find optimal grid resolution or stretching
Numerical modeling of multiple length scales in thermal transport processes
Authors: Jaluria Yogesh 
Published: April 2014

Purpose
– Multiple length and time scales arise in a wide variety of practical and fundamental problems. It is important to obtain accurate and validated numerical simulation results, considering the different scales that exist, in order to predict, design and optimize the behavior of practical thermal processes and systems. The purpose of this paper is to present modeling at the different length scales and then addresses the question of coupling the different models to obtain the overall model for the system or process.

Design/methodology/approach
– Both numerical and experimental methods to obtain results at the different length scales, particularly at micro and nanoscales, are considered. Even though the paper focusses on length scales, multiple time scales lead to similar concerns and are also considered. The two circumstances considered in detail are multiple length scales in different domains and those in the same domain. These two cases have to be modeled quite differently in order to obtain a model for the overall process or system. The basic considerations involved in such a modeling are discussed. A wide range of thermal processes are considered and the methods that may be used are presented. The models employed must be validated and the accuracy of the simulation results established if the simulation results are to be used for prediction, control and design.

Findings
– Of particular interest are concerns like verification and validation, imposition of appropriate boundary conditions, and modeling of complex, multimode transport phenomena in multiple scales. Additional effects such as viscous dissipation, surface tension, buoyancy and rarefaction that could arise and complicate the modeling are discussed. Uncertainties that arise in material properties and in boundary conditions are also important in design and optimization. Large variations in the geometry and coupled multiple regions are also discussed.

Research limitations/implications
– The paper is largely focussed on multiple-scale considerations in thermal processes. Both numerical modeling/simulation and experimentation are considered, with the latter being used for validation and physical insight.

Practical implications
– Several examples from materials processing, environmental flows and electronic systems, including data centers, are given to present the different techniques that may be used to achieve the desired level of accuracy and predictability.

Originality/value
– Present state of the art and future needs in this interesting and challenging area are discussed, providing the impetus for further work. Different methods for treating multiscale problems are presented.
Numerical modeling of bubble-induced flow patterns in champagne glasses
Authors: Beaumont Fabien , Popa Catalin , Liger Belair Gérard , Polidori Guillaume 
Published: April 2014

Purpose
– Very recently, driven by glassmakers and champagne houses, attention has been paid to the way to control effervescence and bubble nucleation. It was demonstrated that ascending bubbles act like many swirling motion generators in champagne glasses. It is the reason why a numerical modeling of flow dynamics induced by the effervescence in a glass of champagne has been carried out for the first time using the finite volume method by Computational Fluid Dynamics (CFD). The paper aims to discuss these issues.

Design/methodology/approach
– In order to define source terms for flow regime and to reproduce accurately the nucleation process at the origin of effervescence, specific subroutines for the gaseous phase have been added to the main numerical model. These subroutines allow the modeling of bubbles behavior based on semi-empirical formulas relating to bubble diameter and velocity or mass transfer evolutions.

Findings
– Details and development of the steps of modeling are presented in this paper, showing a good agreement between the results obtained by CFD simulations in a reference case of those from laser tomography and Particle Image Velocimetry experiments, validating the present model.

Originality/value
– A numerical modeling of flow dynamics induced by the effervescence in a glass of champagne has been carried out for the first time using the finite volume method by CFD.
Effects of rear spoilers on ground vehicle aerodynamic drag
Authors: Sadettin Hamut Halil , El-Emam Rami S. , Aydin Murat , Dincer Ibrahim 
Published: April 2014

Purpose
– The purpose of this paper is to examine the aerodynamic effects of rear spoiler geometry on a sports car. Today, due to economical, safety and even environmental concerns, vehicle aerodynamics play a much more significant role in design considerations and rear spoilers play a major role in this area.

Design/methodology/approach
– A 2-D vehicle geometry of a race car is created and solved using the computational fluid dynamics (CFD) solver FLUENT version 6.3. The aerodynamic effects are analyzed under various vehicle speeds with and without a rear spoiler. The main results are compared to a wind tunnel experiment conducted with 1/18 replica of a Nascar.

Findings
– By the CFD analysis, the drag coefficient without the spoiler is calculated to be 0.31. When the spoiler is added to the geometry, the drag coefficient increases to 0.36. The computational results with the spoiler are compared with the experimental data, and a good agreement is obtained within a 5.8 percent error band. The uncertainty associated with the experimental results of the drag coefficient is calculated to be 6.1 percent for the wind tunnel testing. The sources of discrepancies between the experimental and numerical results are identified and potential improvements on the model and experiments are provided in the paper. Furthermore, in the CFD model, it is found that the addition of the spoiler caused a decrease in the lift coefficient from 0.26 to 0.05.

Originality/value
– This paper examines the effects of rear spoiler geometry on vehicle aerodynamic drag by comparing the CFD analysis with wind tunnel experimentation and conducting an uncertainty analysis to assess the reliability of the obtained results.
Boundary layer flow near stagnation-points on a vertical surface with slip in the presence of transverse magnetic field
Authors: Yakubu Seini Ibrahim , Oluwole Makinde Daniel 
Published: April 2014

Purpose
– The purpose of this paper is to investigate the MHD boundary layer flow of viscous, incompressible and electrically conducting fluid near a stagnation-point on a vertical surface with slip.

Design/methodology/approach
– In the study, the temperature of the surface and the velocity of the external flow are assumed to vary linearly with the distance from the stagnation-point. The governing differential equations are transformed into systems of ordinary differential equations and solved numerically by a shooting method.

Findings
– The effects of various parameters on the heat transfer characteristics are discussed. Graphical results are presented for the velocity and temperature profiles whilst the skin-friction coefficient and the rate of heat transfers near the surface are presented. It is observed that the presence of the magnetic field increases the skin-friction coefficient and the rate of heat transfer near the surface towards the stagnation-point.

Originality/value
– The presence of magnetic field increases the skin-friction coefficient and the rate of heat transfer near the surface towards the stagnation-point.
Inverse thermal analysis of the neonatal brain cooling process
Authors: Łaszczyk Joanna , Maczko Anna , Walas Wojciech , J. Nowak Andrzej 
Published: April 2014

Purpose
– This paper aims to test the inverse analysis, based on the standard least-square method, which will finally lead to find the appropriate parameters of modelling of the brain cooling process.

Design/methodology/approach
– To test the presented in this paper method of inverse analysis the numerical simulations of the bioheat transfer process in the neonatal body were performed. To model the bioheat transfer the Pennes bioheat equation and the modified Fiala model were applied.

Findings
– The performed tests of the inverse analysis proved that it is possible to estimate the proper parameters of the process using this tool, but always with the small mistake.

Research limitations/implications
– The presented method still requires a lot of tests. The test with the data from real measurements can be very valuable.

Practical implications
– The determination of the proper parameters of the bioheat transfer in the neonatal body can finally be used to perform the numerical simulations of the brain cooling process.

Social implications
– The performance of the numerical simulations of the brain cooling process in the proper way can finally helps protect newborns’ health and life.

Originality/value
– In the paper the attempt of the inverse analysis in order to determine the parameters of bioheat transfer in the newborn's body is made.
Mixed convection boundary layer flow along vertical thin needles in nanofluids
Authors: Trimbitas Radu , Grosan Teodor , Pop Ioan 
Published: April 2014

Purpose
– The purpose of this paper is to theoretically study the problem of mixed convection boundary layer flow and heat transfer past a vertical needle with variable wall temperature using nanofluids. The similarity equations are solved numerically for copper nanoparticles in the based fluid of water to investigate the effect of the solid volume fraction parameter of the fluid and heat transfer characteristics. The skin friction coefficient, Nusselt number, and the velocity and temperature profiles and are graphically presented and discussed.

Design/methodology/approach
– The transformed system of ordinary differential equations was solved using the function bvp4c from Matlab. The relative tolerance was set to 1e-10. For the study of the stability the authors also used the bvp4c function in combination with chebfun package from Matlab.

Findings
– It is found that the solid volume fraction affects the fluid flow and heat transfer characteristics. The numerical results for a regular fluid and forced convection flow are compared with the corresponding results reported by Chen and Smith. The solutions exists up to a critical value of λ, beyond which the boundary layer separates from the surface and the solution based upon the boundary-layer approximations is not possible

Originality/value
– The paper describes how multiple (dual) solutions for the flow reversals are obtained. A stability analysis for this flow reversal has been also done showing that the lower solution branches are unstable, while the upper solution branches are stable.
The effect of thermal radiation on the heat transfer characteristics of lid-driven cavity with a moving surface
Authors: Antar M.A. , Ben-Mansour Rached , Ahmed Al-Dini Salem 
Published: April 2014

Purpose
– 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.

Design/methodology/approach
– 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.

Findings
– 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.

Research limitations/implications
– The study is limited to laminar flow case.

Practical implications
– 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.

Originality/value
– 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
Three weighted residual methods based on Jeffery-Hamel flow
Authors: Ganji D.D. , Hatami Mohammad 
Published: April 2014

Purpose
– The purpose of this paper is to demonstrate the eligibility of the weighted residual methods (WRMs) applied to Jeffery-Hamel Flow. Selecting the most appropriate method among the WRMs and discussing about Jeffery-Hamel flow's treatment in divergent and convergent channels are the other important purposes of the present research.

Design/methodology/approach
– Three analytical methods (collocation, Galerkin and least square method) have been applied to solve the governing equations. The reliability of the methods is also approved by a comparison made between the forth order Runge-Kutta numerical method.

Findings
– The obtained solutions revealed that WRMs can be simple, powerful and efficient techniques for finding analytical solutions in science and engineering non-linear differential equations.

Originality/value
– It could be considered as a first endeavor to use the solution of the Jeffery-Hamel flow using these kind of analytical methods along with the numerical approach.
The antecedents of satisfaction and revisit intentions for full-service restaurants
Authors: Marinkovic Veljko , Senic Vladimir , Ivkov Danijela , Dimitrovski Darko , Bjelic Marija 
Published: April 2014

Purpose– The purpose of this paper is to identify the antecedents of satisfaction and revisit intentions for full-service restaurants. The economic crisis is known to have had a deep impact on consumer behavior with regards to restaurants and this study is primarily focussed on exploring the effects on the traditional antecedents of satisfaction and revisit intentions as full-time restaurants attempt to reposition their offer.Design/methodology/approach– The study involved 218 respondents who were guests of full-service restaurants. In terms of statistical analyses, confirmative factor analysis was used to test the suitability of the proposed model for measuring satisfaction and revisit intentions, while structural equation modeling was employed to analyze the relationship among variables of the conceptualized model.Findings– The results confirmed the significant impact of atmosphere and quality of interaction on guest satisfaction. It was interesting to notice that perceived price has no statistically significant impact on guest satisfaction. In addition, satisfaction, along with atmosphere and perceived price emerged as a significant trigger of revisit intentions. While measuring impact of atmosphere and perceived price on revisit intentions, both direct and indirect effects were measured.Originality/value– This study emphasizes in particular, the significance of revisit intention as an important behavioral reaction and reveals its antecedents. In a limited number of studies, models for understanding triggers of revisit intention were developed as separate variables, rather than as components of behavioral reactions. In that context, the tested model identifies causal relationships between latent variables. Restaurants involved in the survey are full-service restaurants dealing with the changing behavior of guests who are heavily impacted by the economic crisis. Guests show a tendency to reduce their visits to restaurants in these circumstances, forcing restaurants to reformulate their service offering in order to align with changing customers’ needs.
Brand strategies in social media
Authors: Tsimonis Georgios , Dimitriadis Sergios 
Published: April 2014

Purpose
– The purpose of this paper is to: first, examine why companies create brand pages in social media, how they use them, what policies and strategies they follow, and what outcomes do they expect; and second – from firms’ point of view – how users are benefited from such pages.

Design/methodology/approach
– A qualitative study approach was employed for this study. Data were collected from personal interviews with 14 marketing managers responsible for the social media activity of their company, providing preliminary evidence about the actions firms take, the motivations that led them to getting involved, and the derived outcomes.

Findings
– The main actions of the firm are making prize competitions, announcing new products/services, interacting with fans, providing advice and useful information, and handling customer service issues. The basic motivations are the increasing popularity of social media, competitors’ presence, headquarters’ strategy, and cost reduction pressure. Interact with customers, create/enhance relationships with customers, brand awareness, customer engagement, promote products/increase of sales, and the more targeted acquisition of new customers, were referred to as the main expected outcomes for companies.

Research limitations/implications
– Given the qualitative nature of the study and the emerging field of research about social media, findings should be considered as preliminary and exploratory. Interviews with companies from more sectors and also with social media users will provide a more comprehensive view of the topic.

Practical implications
– The paper identifies several opportunities for company managers, suggesting practices for effective social media handling.

Originality/value
– Considering the rapid development of social media and their penetration in business marketing actions, this paper is an exploratory step toward the ways firms utilize social media channels.
Store personality and consumer store choice behaviour: an empirical examination
Authors: Das Gopal 
Published: April 2014

Purpose– The purpose of this paper is to explore the influences of store attributes on store personality dimensions across different consumer segments. Subsequently, the study examines impact of store personality dimensions on consumer store choice behaviour.Design/methodology/approach– A mall-intercept survey was undertaken using a systematic sampling of department store shoppers of age 18 years and above in Kolkata, a metropolitan city of India. Questionnaire was used to collect data from busy shopping malls or centres located in different places of Kolkata. Multiple regression analysis is used to examine the objectives of this study.Findings– Results revealed that different sets of store attributes positively affect the various store personality dimensions differently across the segments. The study also found the positive impacts of store personality dimensions on consumer store choice behaviour.Originality/value– Arguably, this study is the first to explore the link between store attributes and store personality across the consumer segments, and the impacts of store personality dimensions on consumer store choice behaviour.