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Article
Publication date: 1 October 2004

Jaw‐Ren Lin, Rong‐Fang Lu and Won‐Hsion Liao

The analysis of squeeze‐film performances between curved annular plates with an electrically conducting fluid in the presence of a transverse magnetic field is presented…

Abstract

The analysis of squeeze‐film performances between curved annular plates with an electrically conducting fluid in the presence of a transverse magnetic field is presented in this study. The magneto‐hydrodynamic (MHD) Reynolds‐type equation for squeezing‐film curved annular disks is derived using the continuity equation and the MHD motion equations. A closed‐form solution for the squeezing film pressure is obtained, and applied to predict the MHD squeeze‐film characteristics. According to the results obtained, the presence of applied magnetic fields signifies an increase in the MHD squeeze‐film pressure. Compared with the classical non‐conducting‐lubricant case, the magnetic‐field effect characterized by the Hartmann number provides an enhancement to the MHD load‐carrying capacity and the response time, especially for larger values of the curved shape parameter or smaller values of inner‐outer radius ratio of the curved annular disks.

Details

Industrial Lubrication and Tribology, vol. 56 no. 5
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 27 June 2019

Ereny Gobrial

Children and young people with comorbid intellectual disabilities (ID) and autism spectrum disorders (ASD) are more likely to exhibit comorbid mental health disorders (MHD

Abstract

Purpose

Children and young people with comorbid intellectual disabilities (ID) and autism spectrum disorders (ASD) are more likely to exhibit comorbid mental health disorders (MHD) and other significant behaviours (SB) in addition to the core symptoms of ASD. The purpose of this paper is to identify the prevalence of comorbid MHD and behaviours in children and young people with ID and ASD in Egypt.

Design/methodology/approach

The Reiss scale for children’s dual diagnosis was administered by parents and teachers of 222 Egyptian children and young people with mild/moderate ID and ASD to screen for MHD and SB. The mean age of children and young people was 12.3 years (SD = 3.64), with 75.6 per cent male.

Findings

The results revealed that 62.2 per cent of children and young people with ID and ASD had high rates of comorbid MHD and behaviour disorders were shown in 64.4 per cent of the participated children and young people. The results identified anger, anxiety and psychosis being the most frequently diagnosed disorders while crying spells and pica were the most SB. No differences were found between the male and female with ID and ASD in the current study.

Research limitations/implications

Mental health assessment of children and young people with ID and ASD will help to highlight the needs of these vulnerable children and develop the appropriate services.

Originality/value

The findings highlight the prevalence of MHD in children and young people with ID and ASD in Egypt. This has implications on the assessment of comorbid disorders and services needed for children with ID and ASD in Egypt.

Details

Advances in Mental Health and Intellectual Disabilities, vol. 13 no. 5
Type: Research Article
ISSN: 2044-1282

Keywords

Article
Publication date: 2 June 2022

Mohammed Kardoudi, Mohamed Nabhani and Mohamed El Khlifi

This paper aims to present a numerical model to examine the finite magneto-hydrodynamic (MHD) journal bearings performances including both non-Newtonian couple stress and…

Abstract

Purpose

This paper aims to present a numerical model to examine the finite magneto-hydrodynamic (MHD) journal bearings performances including both non-Newtonian couple stress and bearing deformation impacts.

Design/methodology/approach

Based upon the MHD and Stokes theories, a novel expression of modified Reynolds equation including bearing deformation is obtained. The bearing elastic deformation impact is predicted by means of the Winkler model. Using the numerical differentiation approach, the film pressure is iteratively solved. Different bearing characteristics are then numerically calculated. The validity of the proposed model was verified by comparing with some particular cases from literature.

Findings

From the numerical presented results, it is demonstrated that the conducting couple stress lubricant with an applied radial magnetic field results in an induced electric current density and thus significantly improves the performances of elastic journal bearings. Particularly, the load-carrying capacity is increased, whereas a reduction in friction factor is observed.

Originality/value

This numerical model is original, which combines both non-Newtonian couple stress and bearing deformation impacts on finite MHD journal bearings performances. It provides useful information in designing MHD journal bearings, given the lack of experimental studies.

Details

Industrial Lubrication and Tribology, vol. 74 no. 6
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 19 September 2016

Yue Ji, Xingfei Li, Tengfei Wu, Cheng Chen and Ying Yang

The evaluations of the magnetohydrodynamics angular rate sensor (MHD ARS) in its applications necessitate further improvements in the sensor’s dynamic measurement ability…

Abstract

Purpose

The evaluations of the magnetohydrodynamics angular rate sensor (MHD ARS) in its applications necessitate further improvements in the sensor’s dynamic measurement ability. The magnetic field of the MHD ARS is a key factor in the sensor’s modeling and error analysis. The aim of this study is to illustrate the influence of a non-uniform magnetic field on the sensor.

Design/methodology/approach

Numerical simulation is made using ANSYS FLUNET with the magnetic field calculated by 3D-Magnetostatic. The comparison of the simulation results between uniform and non-uniform magnetic fields is made to reveal and explain the effects of magnetic field inhomogeneity (MFI) on the flow and electric field in detail. Two different structures with different MFIs are designed to confirm the MFI effect on the sensor’s output in simulation and experiment. A cross-correlation experiment and an adaptive filter are carried out to extract the signal to identify the error of the sensor output caused by MFI.

Findings

The MFI effect on the flow field in MHD ARS is found to be insignificant, while its effect on the electric potential is considerable. The comparisons between two kinds of MHD ARS in numerical simulation and experiment show that the MFI effect on the sensor error can be identified by fitting the sensor output. The deviation is mainly generated at the peaks and valleys of an angular vibration.

Originality/value

The study of the MHD ARS under the influence of a non-uniform magnetic field can offer an understanding of the MFI effect on the sensor and an evaluation method of the sensor error caused by the MFI effect.

Details

Sensor Review, vol. 36 no. 4
Type: Research Article
ISSN: 0260-2288

Keywords

Article
Publication date: 1 January 2013

GholamReza Kefayati, Mofid Gorji, Hasan Sajjadi and Davood Domiri Ganji

Magneto hydrodynamic (MHD) flows in fluids is known to have an important effect on heat transfer and fluid flow in various substances while the quality of the substances…

Abstract

Purpose

Magneto hydrodynamic (MHD) flows in fluids is known to have an important effect on heat transfer and fluid flow in various substances while the quality of the substances and the considered shapes can influence the amount of changes. Thus, MHD flows in a different form and widespread alterations in the kind of the material and the power of MHD flow were carried out by lattice Boltzmann method (LBM) in this investigation. The aim of this paper is to identify the ability of LBM for solving MHD flows as the effect of different substances in the presence of the magnetic field changes.

Design/methodology/approach

This method was utilized for solving MHD natural convection in an open cavity while Hartmann number varies from 0 to 150 and Rayleigh number is considered at values of Ra=103, 104 and 105, with the Prandtl number altering in a wide range of Pr=0.025, 0.71 and 6.2. An appropriate validation with previous numerical investigations demonstrated that this attitude is a suitable method for MHD problems.

Findings

Results show the alterations of Prandtl numbers influence the isotherms and the streamlines widely at different Rayleigh and Hartmann numbers simultaneously. Moreover, heat transfer declines with the increment of Hartmann number, while this reduction is marginal for Ra=103 by comparison with other Rayleigh numbers. The effect of the magnetic field on the average Nusselt number at Liquid Gallium (Pr=0.025) is the least among considered materials.

Originality/value

In this method, just the force term at LBM changes in the presence of MHD flow as the added term rises from the classic equations of fluids mechanic. Moreover, all parameters of the added term and the method of their computing are exhibited.

Details

Engineering Computations, vol. 30 no. 1
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 8 April 2014

Neminath Bhujappa Naduvinamani and Mareppa Rajashekar

The purpose of this article is to analyse the effects of surface roughness on the magneto-hydrodynamic (MHD) squeeze-film characteristics between a sphere and a porous…

Abstract

Purpose

The purpose of this article is to analyse the effects of surface roughness on the magneto-hydrodynamic (MHD) squeeze-film characteristics between a sphere and a porous plane surface, which have not been studied so far.

Design/methodology/approach

The analytical model takes into account the effect of porosity by assuming that the flow in the porous matrix obeys modified Darcy's law. The stochastic MHD Reynold's type equation is derived by using the Christensen's stochastic method developed for hydrodynamic lubrication of rough surfaces. Two types of one-dimensional surface roughness (radial and azimuthal) patterns are considered.

Findings

The expressions for the mean MHD squeeze-film pressure and mean load-carrying capacity are obtained numerically. The results are shown graphically for selected representative parametric values. It is found that the response time increases significantly for the MHD case as compared to the corresponding non-conducting lubricants. The effect of roughness parameter is to increase/decrease the load-carrying capacity and the response time for azimuthal/radial roughness patterns as compared to the smooth case. Also, the effect of porous parameter is to decrease the load-carrying capacity and response time as compared to the solid case.

Originality/value

In this paper, an attempt has been made to analyse the combined effects of surface roughness and permeability on the MHD squeeze-film characteristics between a sphere and a plane surface.

Details

Industrial Lubrication and Tribology, vol. 66 no. 3
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 20 February 2017

Kellie Buckley-Walker, Trevor P. Crowe and Peter Caputi

Caring for a person with a substance use disorder (SUD) and/or mental health disorder (MHD) represents a significant burden for family members. The features of…

Abstract

Purpose

Caring for a person with a substance use disorder (SUD) and/or mental health disorder (MHD) represents a significant burden for family members. The features of “carers/family members” experiences reflect trauma signatures. Consequently, working through this trauma for carers corresponds with psychological recovery, empowerment processes and intrapersonal/interpersonal needs. The purpose of this paper is to outline a framework called the “personal and relational empowerment (PRE)” framework which enables family support practitioners to help family members to be able to take control of their own lives, develop meaningful relationships and live purposeful and fulfilling lives, regardless of whether the person with the SUD and/or MHD is in recovery or not.

Design/methodology/approach

This paper critically reviews existing frameworks for carer recovery, through a systematic literature search, and proposes a “PRE” alternative to redress the shortfalls in these existing frameworks.

Findings

The PRE framework takes a multi-level needs-based approach to understand carer recovery. This framework links the concepts – psychological recovery, empowerment processes and intrapersonal/interpersonal needs.

Practical implications

The PRE framework recognises the importance of recovery support practitioners being able to balance the immediate carer crisis intervention needs responses with personal growth and well-being supporting interventions.

Originality/value

The PRE framework of family recovery attempts to answer the need to broaden the focus on the family journey to better reflect the principles and practices of contemporary SUD and/or MHD recovery-based support.

Details

Advances in Dual Diagnosis, vol. 10 no. 1
Type: Research Article
ISSN: 1757-0972

Keywords

Article
Publication date: 9 October 2019

Bidemi Olumide Falodun and Adeola John Omowaye

This paper aims to address the problem of double-diffusive magnetohydrodynamics (MHD) non-Darcy convective flow of heat and mass transfer over a stretching sheet embedded…

Abstract

Purpose

This paper aims to address the problem of double-diffusive magnetohydrodynamics (MHD) non-Darcy convective flow of heat and mass transfer over a stretching sheet embedded in a thermally-stratified porous medium. The controlling parameters such as chemical reaction parameter, permeability parameter, etc., are extensively discussed and illustrated in this paper.

Design/methodology/approach

With the help of appropriate similarity variables, the governing partial differential equations are converted into ordinary differential equations. The transformed equations are solved using the spectral homotopy analysis method (SHAM). SHAM is a numerical method, which uses Chebyshev pseudospectral and homotopy analysis method in solving science and engineering problems.

Findings

The effects of all controlling parameters are presented using graphical representations. The results revealed that the applied magnetic field in the transverse direction to the flow gives rise to a resistive force called Lorentz. This force tends to reduce the flow of an electrically conducting fluid in the problem of heat and mass transfer. As a result, the fluid velocity reduces in the boundary layer. Also, the suction increases the velocity, temperature, and concentration of the fluid, respectively. The present results can be used in complex problems dealing with double-diffusive MHD non-Darcy convective flow of heat and mass transfer.

Originality/value

The uniqueness of this paper is the examination of double-diffusive MHD non-Darcy convective flow of heat and mass transfer. It is considered over a stretching sheet embedded in a thermally-stratified porous medium. To the best of the knowledge, a problem of this type has not been considered in the past. A novel method called SHAM is used to solve this modelled problem. The novelty of this method is its accuracy and fastness in computation.

Details

World Journal of Engineering, vol. 16 no. 6
Type: Research Article
ISSN: 1708-5284

Keywords

Article
Publication date: 1 September 2002

Michele Ciofalo and Fabrizio Cricchio

The buoyancy‐driven magnetohydrodynamic flow in a cubic enclosure was investigated by three‐dimensional numerical simulation. The enclosure was volumetrically heated by a…

Abstract

The buoyancy‐driven magnetohydrodynamic flow in a cubic enclosure was investigated by three‐dimensional numerical simulation. The enclosure was volumetrically heated by a uniform power density and cooled along two opposite vertical walls, all remaining walls being adiabatic. A uniform magnetic field was applied orthogonally to the gravity vector and to the temperature gradient. The Prandtl number was 0.0321 (characteristic of Pb–17Li at 300°C), the Rayleigh number was 104, and the Hartmann number was made to vary between 0 and 2×103. The steady‐state Navier–Stokes equations, in conjunction with a scalar transport equation for the fluid's enthalpy and with the Poisson equation for the electrical potential, were solved by a finite volume method using a purposely modified CFD code and a computational grid with 643 nodes in the fluid. Emphasis was laid on the effects of increasing the Hartmann number on the complex three‐dimensional flow and current pattern.

Details

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

Keywords

Article
Publication date: 5 September 2016

J. Rajakumar, P. Saikrishnan and A. Chamkha

The purpose of this paper is to consider axisymmetric mixed convection flow of water over a sphere with variable viscosity and Prandtl number and an applied magnetic field.

Abstract

Purpose

The purpose of this paper is to consider axisymmetric mixed convection flow of water over a sphere with variable viscosity and Prandtl number and an applied magnetic field.

Design/methodology/approach

The non-similar solutions have been obtained from the origin of the streamwise co-ordinate to the point of zero skin friction using quasilinearization technique with an implicit finite-difference scheme.

Findings

The effect of M is not notable on the temperature and heat transfer coefficient when λ is large. The skin friction coefficient and velocity profile are enhance with the increase of MHD parameter M when λ is small. Viscous dissipation has no significant on the skin friction coefficient under MHD effect. For M=1, the movement of the slot or slot suction or slot injection do not cause any effect on flow separation. The slot suction and the movement of the slot in downstream direction delay the point of zero skin friction for M=0.

Originality/value

The present results are original and new for water boundary-layer flow over sphere in mixed convection flow with MHD effect and non-uniform mass transfer. So this study would be useful in analysing the skin friction and heat transfer coefficient on sphere of mixed convection flow of water boundary layer with MHD effect.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 26 no. 7
Type: Research Article
ISSN: 0961-5539

Keywords

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