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Article
Publication date: 9 April 2019

Mohsen Izadi, Nemat M. Maleki, Ioan Pop and S.A.M. Mehryan

This paper aims to numerically investigate the natural convection heat transfer of a hybrid nanofluid into a porous cavity exposed to a variable magnetic field.

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Abstract

Purpose

This paper aims to numerically investigate the natural convection heat transfer of a hybrid nanofluid into a porous cavity exposed to a variable magnetic field.

Design/methodology/approach

The non-linear elliptical governing equations have been solved numerically using control volume based finite element method. The effects of different governing parameters including Rayleigh number (Ra = 103 − 106), Hartman number (Ha = 0 − 50), volume fraction of nanoparticles (φ = 0 − 0.02), curvature of horizontal isolated wall (a = 0.85 − 1.15), porosity coefficient (ε = 0.1 − 0.9) and Darcy number (Da = 10−5 − 10−1) have been studied.

Findings

The results indicate that at low Darcy numbers close to 0, the average Nusselt number Nua enhances as porosity coefficient increases. For a = 1 and a = 1.15 in comparison with a = 0.85, the stretching of the isothermal lines is maintained from the left side to the right side and vice versa, which indicates increased natural convection heat transfer for this configuration of the top and bottom walls. In addition, at higher Rayleigh numbers, by increasing the Hartmann number, a significant decrease is observed in the Nusselt number, which can be attributed to the decreased power of the flow.

Originality/value

The authors believe that all the results, both numerical and asymptotic, are original and have not been published elsewhere.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 29 no. 4
Type: Research Article
ISSN: 0961-5539

Keywords

Available. Open Access. Open Access
Article
Publication date: 17 June 2020

Mohammed Aboramadan and Khalid Abed Dahleez

This study aims to investigate the effects of transformational and transactional leaders’ behaviors on employees’ affective commitment and organizational citizenship behavior in…

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Abstract

Purpose

This study aims to investigate the effects of transformational and transactional leaders’ behaviors on employees’ affective commitment and organizational citizenship behavior in the context of nonprofit organizations (NPOs). Additionally, this study attempts to examine the role of work engagement, as an intervening mechanism as work engagement in NPOs has been empirically neglected (Park et al., 2018).

Design/methodology/approach

Data were conducted from 400 employees working in Italian NPOs in the North of Italy. For verifying the hypotheses of this study, structural equation modeling techniques were implemented.

Findings

It was found that both transformational and transactional leaderships influenced positively affective commitment and organizational citizenship behavior, and work engagement was revealed to have significant positive mediating effects on the relationship between the variables examined in this study.

Practical implications

The results of this study may be beneficial to leaders and supervisors of NPOs, specifically regarding the influence of the leaders’ behaviors on the employees’ outcomes.

Originality/value

Due to the limited number of studies conducted on leadership in nonprofit organizations, this study theoretically and empirically contributes to the leadership literature as it is the first study to investigate the two styles of leadership on work-related outcomes via work engagement in the nonprofit sector.

Details

Journal of Management Development, vol. 39 no. 7/8
Type: Research Article
ISSN: 0262-1711

Keywords

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