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Article
Publication date: 1 March 2005

A. Campo, O. Manca and B. Morrone

To address the impact of adding insulated plate extensions at the entrance of an isoflux vertical parallel‐plate channel on the thermal performances of natural convection in air…

621

Abstract

Purpose

To address the impact of adding insulated plate extensions at the entrance of an isoflux vertical parallel‐plate channel on the thermal performances of natural convection in air for these systems.

Design/methodology/approach

The model relies on the full elliptic conservation equations which are solved numerically in a composite three‐part computational domain by means of the finite‐volume method.

Findings

Results are reported in terms of wall temperatures, induced mass flow rates, as well as velocity and temperature profiles of the air for various thermal and geometric parameters. The wall temperatures increase when the extensions are appended at the inlet of the channel. Wall temperature profiles strongly depend on the Rayleigh number and the dependence of the heated channel aspect ratio is weaker than the extension ratio. Velocity and temperature profiles modify inside the heated channel due to the thermal development. In addition, correlation equations for main engineering quantities, such as the induced mass flow rate, average Nusselt number and dimensionless maximum wall temperature in terms of the channel Rayleigh number, channel aspect ratio and extension ratio are presented.

Research limitations/implications

The investigation has been carried out in the following ranges: 103‐105 for the Rayleigh number, 5.0‐15.0 for the channel aspect ratio and 1.0‐5.0 for the extension ratio. The hypotheses on which the present analysis is based are: two‐dimensional, laminar and steady‐state flow, constant thermophysical properties with the Boussinesq approximation.

Practical implications

Thermal design of heating systems in manufacturing processes, evaluation of heat convective coefficients and maximum attained wall temperatures.

Originality/value

Evaluation of the thermal and velocity fields and correlation equations for the Nusselt number and maximum dimensionless temperatures in natural convection in air for vertical channels. The paper is useful to thermal designers.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 15 no. 2
Type: Research Article
ISSN: 0961-5539

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Publication date: 25 July 2014

Anastasia Morrone and Sue B. Workman

This chapter focuses on learning space design for students’ technology-rich lifestyles, in particular the evolution and future of learning spaces in the United States. JISC design…

Abstract

This chapter focuses on learning space design for students’ technology-rich lifestyles, in particular the evolution and future of learning spaces in the United States. JISC design principles – bold, supportive, future proof, creative, and enterprising – frame discussion in the chapter’s first section, “Planning for the learning spaces of tomorrow.” The section begins with pioneering work in the field and follows with recent learning spaces (both classrooms and informal learning environments) that seek new and innovative ways for students to collaborate. Examples clearly point to students’ need for continual access to flexible, tech-rich spaces that support their work and study habits.

The chapter’s second section, “The future of learning spaces: On-demand apps and Bring Your Own Technology (BYOT),” is a case study focused on software virtualization’s influence on learning space design at Indiana University. The section brings in examples from the University of South Florida and the University of Iowa, asserting that physical and virtual learning spaces must be designed to come together seamlessly, echoing students’ on-the-go lifestyles and constant connectedness. Ultimately, the section makes a bold contention about the evolution of learning spaces: Any space can become a tech-rich learning environment, if students have access to virtualized software.

Throughout, the chapter touches on compelling questions about meeting the learning needs of digital natives: How do we challenge traditional educational paradigms? Can we flip the classroom to further the potential of all learners? What is the role of collaboration in learning? Which models will energize and inspire learners and instructors of the future?

Details

The Future of Learning and Teaching in Next Generation Learning Spaces
Type: Book
ISBN: 978-1-78350-986-7

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Article
Publication date: 1 September 2002

Assunta Andreozzi, Oronzio Manca and Vincenzo Naso

Research on natural convection in open channels is very extensive due to its role in many engineering applications such as thermal control of electronic systems. In this paper, a…

491

Abstract

Research on natural convection in open channels is very extensive due to its role in many engineering applications such as thermal control of electronic systems. In this paper, a parametric analysis is carried out in order to add knowledge of heat transfer in air natural convection for a symmetrically heated vertical parallel plate channel with a central auxiliary heated or adiabatic plate. The two‐dimensional steady‐state problem is solved by means of the stream function–vorticity approach and the numerical solution is carried out by means of the control volume method. Results are obtained for both a heated and unheated auxiliary plate, for a Rayleigh number in the range 103–106, for a ratio of the auxiliary plate height to the channel plate height equal to 0, 0.5 and 1 and for a ratio of the channel length to the channel gap in the range 5–15. Correlations for maximum wall temperatures and average channel Nusselt numbers are proposed.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 12 no. 6
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 1 April 2006

Francisco Marcondes, Vinícius de Souza Melo and Jose Maurício Gurgel

To investigate the natural convection in open‐ended parallel, convergent, and divergent channels using a fully elliptic procedure without extending the domain outside the channel…

697

Abstract

Purpose

To investigate the natural convection in open‐ended parallel, convergent, and divergent channels using a fully elliptic procedure without extending the domain outside the channel for the application of the boundary conditions at the inlet and outlet of the channels.

Design/methodology/approach

The model is two‐dimensional and fully elliptic in x and y directions, and the equations are solved only inside the channel by the finite volume method using a co‐located arrangement with a segregated procedure and boundary fitted coordinates. The pressure‐velocity coupling is solved by the PRIME algorithm.

Findings

The results are shown in terms of velocity vectors, streamlines, isotherms, and the local and the average Nusselt number for all fluids and configurations investigated. For high values of the Rayleigh number, a recirculation region in the outlet of all investigated configurations and Prandtl numbers was observed. Based on the results, a single correlation is proposed to evaluate the average Nusselt number for all fluids and configurations analyzed.

Research limitations/implications

The shown results are based on the following hypothesis: steady‐state, two‐dimensional, laminar flow, and Boussinesq's aproximation. The results are presented in following range of parameters: 105<(Smax/L)RaSmax<108, where Smax denotes the maximum distance between the plates and Ra denotes the Rayleigh number; half angle of convergence or divergence (θ): 5° and 15°; and Prandtl numbers: 0.7, 5.0, and 88.

Originality/value

Local and average Nusselt numbers, for Prandtl numbers varying from 0.70 to 88, and a correlation for the average Nusselt number for all fluids and configurations are presented. The results presented in this paper are useful to engineers and researchers involved in thermal design and numerical methods.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 16 no. 3
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 20 April 2010

Antonio Campo, Richard Johnson, Mark D. Landon and Luben Cabezas‐Gómez

The purpose of this paper is to provide a suitable linkage between a computational fluid dynamics code and a shape optimization code for the analysis of heat/fluid flow in forced…

289

Abstract

Purpose

The purpose of this paper is to provide a suitable linkage between a computational fluid dynamics code and a shape optimization code for the analysis of heat/fluid flow in forced convection channels normally used in the cooling of electronic equipment.

Design/methodology/approach

A parallel‐plate channel with a discrete array of five heat sources embedded in one plate with the other plate insulated constitutes the starting model. Using water as the coolant medium, the objective is to optimize the shape of the channel employing a computerized design loop. The two‐part optimization problem is constrained to allow only the unheated plate to deform, while maintaining the same inlet shape and observing a maximum pressure drop constraint.

Findings

First, the results for the linearly deformed unheated plate show significant decrease in the plate temperatures of the heated plate, with the maximum plate temperature occurring slightly upstream of the outlet. Second, when the unheated plate is allowed to deform nonlinearly, a parabolic‐like shaped plate is achieved where the maximum plate temperature is further reduced, with a corresponding intensification in the local heat transfer coefficient. The effectiveness of the computerized design loop is demonstrated in complete detail.

Originality/value

This article offers a simple, harmonious technique for optimizing the shape of forced convection channels subjected to pre‐set design constraints.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 20 no. 3
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 21 September 2010

Assunta Andreozzi, Bernardo Buonomo and Oronzio Manca

The purpose of this paper is to evaluate the thermal and fluid dynamic behaviors of natural convection in a vertical channel‐chimney system heated symmetrically at uniform heat…

408

Abstract

Purpose

The purpose of this paper is to evaluate the thermal and fluid dynamic behaviors of natural convection in a vertical channel‐chimney system heated symmetrically at uniform heat flux in order to detect the different fluid motion structures inside the chimney, such as the cold inflow from the outlet section of the chimney and the reattachment due to the hot jet from the channel, for different extension and expansion ratios of the adiabatic extensions.

Design/methodology/approach

The model is constituted by two‐dimensional steady‐state fully elliptic conservation equations which are solved numerically in a composite three‐part computational domain by means of the finite‐volume method.

Findings

Stream function and temperature fields in the system are presented in order to detect the different fluid motion structures inside the chimney, for different extension and expansion ratios of the adiabatic extensions. The analysis allows to evaluate the effect of the channel aspect ratio on the thermal and fluid dynamic behaviors on a channel‐chimney system and thermal and geometrical conditions corresponding to a complete downflow. Guidelines to estimate critical conditions related to the beginning of flow separation and complete downflow are given in terms of order of magnitude of Rayleigh and Froude numbers.

Research limitations/implications

The hypotheses on which the present analysis is based are: two‐dimensional, laminar and steady‐state flow, constant thermophysical properties with the Boussinesq approximation. The investigation is carried out in the following ranges: from 100 to 100,000 for the Rayleigh number, from 5.0 to 20 for the aspect ratio, from 1.0 to 4.0 for the expansion ratio and from 1.5 to 4 for the extension ratio.

Practical implications

Thermal design of heating systems in different technical fields, such as in electronic cooling and in building ventilation and houses solar components, evaluation of heat convective coefficients and guidelines to estimate critical conditions related to the beginning of flow separation and complete downflow.

Originality/value

The paper is useful to thermal designers because of its evaluation of the thermal and velocity fields, correlation for the Nusselt number and guidelines criteria in terms of Rayleigh and Froude numbers to evaluate conditions of flow separation and complete downflow in natural convection in air for vertical channels‐chimney systems.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 20 no. 7
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 14 October 2019

Nagesh Babu Balam and Akhilesh Gupta

Modelling accurately the transient behaviour of natural convection flow in enclosures been a challenging task because of a variety of numerical errors which have limited achieving…

157

Abstract

Purpose

Modelling accurately the transient behaviour of natural convection flow in enclosures been a challenging task because of a variety of numerical errors which have limited achieving the higher order temporal accuracy. A fourth-order accurate finite difference method in both space and time is proposed to overcome these numerical errors and accurately model the transient behaviour of natural convection flow in enclosures using vorticity–streamfunction formulation.

Design/methodology/approach

Fourth-order wide stencil formula with appropriate one-sided difference extrapolation technique near the boundary is used for spatial discretisation, and classical fourth-order Runge–Kutta scheme is applied for transient term discretisation. The proposed method is applied on two transient case studies, i.e. convection–diffusion of a Gaussian Pulse and Taylor Vortex flow having analytical solution.

Findings

Error magnitude comparison and rate of convergence analysis of the proposed method with these analytical solutions establish fourth-order accuracy and prove the ability of the proposed method to truly capture the transient behaviour of incompressible flow. Also, to test the transient natural convection flow behaviour, the algorithm is tested on differentially heated square cavity at high Rayleigh number in the range of 103-108, followed by studying the transient periodic behaviour in a differentially heated vertical cavity of aspect ratio 8:1. An excellent comparison is obtained with standard benchmark results.

Research limitations/implications

The developed method is applied on 2D enclosures; however, the present methodology can be extended to 3D enclosures using velocity–vorticity formulations which shall be explored in future.

Originality/value

The proposed methodology to achieve fourth-order accurate transient simulation of natural convection flows is novel, to the best of the authors’ knowledge. Stable fourth-order vorticity boundary conditions are derived for boundary and external boundary regions. The selected case studies for comparison demonstrate not only the fourth-order accuracy but also the considerable reduction in error magnitude by increasing the temporal accuracy. Also, this study provides novel benchmark results at five different locations within the differentially heated vertical cavity of aspect ratio 8:1 for future comparison studies.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 30 no. 3
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 7 September 2012

M. Rashidzadeh, B. Faridnia and M.R. Ghasemi

The purpose of this paper is to study the effect of synthesis conditions on properties of TiO2 nanoparticles to be used for photocatalysis and also producing TiO2 using a low…

1381

Abstract

Purpose

The purpose of this paper is to study the effect of synthesis conditions on properties of TiO2 nanoparticles to be used for photocatalysis and also producing TiO2 using a low temperature method.

Design/methodology/approach

TiO2 nanoparticles were synthesised via a sol‐gel method at low temperature and the effect of parameters such as: synthesis temperature, HNO3 concentration, calcination temperature and synthesis time on properties of TiO2 were studied. The effects of the physico‐chemical properties of TiO2, its concentration and light intensity on photocatalytic properties of TiO2 nanoparticles were investigated also.

Findings

The results showed that TiO2 with Anatase phase were formed at 80‐100°C by using proper HNO3 concentration, synthesis time and calcinations temperature. Calcinations programme and temperature and also the synthesis time affect the formation of TiO2 crystalline phase (i.e. Rutile and Brookite), their surface area and crystallite size. To evaluate the photocatalytic properties of TiO2 nanoparticles, fluorescein was used as a model molecule. Results showed that degradation of fluorescein could be described by pseudo‐first order kinetics. The effect of TiO2 concentration and light intensity on photocatalytic activity showed that increasing concentration of TiO2 and the light intensity would increase the degradation of fluorescein.

Originality/value

The method used in this work to prepare TiO2 nanoparticles is an economic method for low temperature synthesis of TiO2 nanoparticles with high photocatalytic activity, which could find numerous applications in coating technology.

Details

Pigment & Resin Technology, vol. 41 no. 5
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 1 April 2024

Xiaoxian Yang, Zhifeng Wang, Qi Wang, Ke Wei, Kaiqi Zhang and Jiangang Shi

This study aims to adopt a systematic review approach to examine the existing literature on law and LLMs.It involves analyzing and synthesizing relevant research papers, reports…

561

Abstract

Purpose

This study aims to adopt a systematic review approach to examine the existing literature on law and LLMs.It involves analyzing and synthesizing relevant research papers, reports and scholarly articles that discuss the use of LLMs in the legal domain. The review encompasses various aspects, including an analysis of LLMs, legal natural language processing (NLP), model tuning techniques, data processing strategies and frameworks for addressing the challenges associated with legal question-and-answer (Q&A) systems. Additionally, the study explores potential applications and services that can benefit from the integration of LLMs in the field of intelligent justice.

Design/methodology/approach

This paper surveys the state-of-the-art research on law LLMs and their application in the field of intelligent justice. The study aims to identify the challenges associated with developing Q&A systems based on LLMs and explores potential directions for future research and development. The ultimate goal is to contribute to the advancement of intelligent justice by effectively leveraging LLMs.

Findings

To effectively apply a law LLM, systematic research on LLM, legal NLP and model adjustment technology is required.

Originality/value

This study contributes to the field of intelligent justice by providing a comprehensive review of the current state of research on law LLMs.

Details

International Journal of Web Information Systems, vol. 20 no. 4
Type: Research Article
ISSN: 1744-0084

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Article
Publication date: 26 August 2014

Antonio Campo, Abraham J. Salazar, Diego J. Celentano and Marcos Raydan

The purpose of this paper is to address a novel method for solving parabolic partial differential equations (PDEs) in general, wherein the heat conduction equation constitutes an…

229

Abstract

Purpose

The purpose of this paper is to address a novel method for solving parabolic partial differential equations (PDEs) in general, wherein the heat conduction equation constitutes an important particular case. The new method, appropriately named the Improved Transversal Method of Lines (ITMOL), is inspired in the Transversal Method of Lines (TMOL), with strong insight from the method of separation of variables.

Design/methodology/approach

The essence of ITMOL revolves around an exponential variation of the dependent variable in the parabolic PDE for the evaluation of the time derivative. As will be demonstrated later, this key step is responsible for improving the accuracy of ITMOL over its predecessor TMOL. Throughout the paper, the theoretical properties of ITMOL, such as consistency, stability, convergence and accuracy are analyzed in depth. In addition, ITMOL has proven to be unconditionally stable in the Fourier sense.

Findings

In a case study, the 1-D heat conduction equation for a large plate with symmetric Dirichlet boundary conditions is transformed into a nonlinear ordinary differential equation by means of ITMOL. The numerical solution of the resulting differential equation is straightforward and brings forth a nearly zero truncation error over the entire time domain, which is practically nonexistent.

Originality/value

Accurate levels of the analytical/numerical solution of the 1-D heat conduction equation by ITMOL are easily established in the entire time domain.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 24 no. 7
Type: Research Article
ISSN: 0961-5539

Keywords

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