Search results

1 – 10 of 295
Article
Publication date: 10 December 2018

Taher Armaghani, A.M. Rashad, Omid Vahidifar, S.R. Mishra and A.J. Chamkha

This paper aims to concentrate on the impacts of a discrete heat source location on heat transfer and entropy generation for a Ag-water nanofluid in an open inclined…

Abstract

Purpose

This paper aims to concentrate on the impacts of a discrete heat source location on heat transfer and entropy generation for a Ag-water nanofluid in an open inclined L-shaped cavity.

Design/methodology/approach

The governing partial differential equations for this study are computed by the finite volume method.

Findings

The results show that increasing the inclination angle leads to a rise in heat transfer. It is clear with the increase in the nanoparticles volume fraction that the thermal performance reduces, and it increases when the inclination angle increases.

Originality/value

Because of the continuous literature survey, the authors have not found a study that concentrates on the entropy generation in a wide variety of irregular ducts. Thus, in this paper, they present the analysis of entropy generation in an L-shaped duct experiencing a mixed convective flow with a nanofluid. The authors deal with this geometry because it is very useful in cooling systems of nuclear and chemical reactors and electronic components.

Details

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

Keywords

Article
Publication date: 27 November 2018

Chandra Shekar Balla, C. Haritha, Kishan Naikoti and A.M. Rashad

The purpose of this paper is to investigate the bioconvection flow in a porous square cavity saturated with both oxytactic microorganism and nanofluids.

Abstract

Purpose

The purpose of this paper is to investigate the bioconvection flow in a porous square cavity saturated with both oxytactic microorganism and nanofluids.

Design/methodology/approach

The impacts of the effective parameters such as Rayleigh number, bioconvection number, Peclet number and thermophoretic force, Brownan motion and Lewis number reduces the flow strength in the cavity on the flow strength, oxygen density distribution, motile isoconcentrations and heat transfer performance are investigated using a finite volume approach.

Findings

The results obtained showed that the average Nusselt number is increased with Peclet number, Lewis number, Brownian motion and thermophoretic force. Also, the average Sherwood number increased with Brownian motion and Peclet number and decreased with thermophoretic force. It is concluded that the flow strength is pronounced with Rayleigh number, bioconvection number, Peclet number and thermophoretic force. Brownan motion and Lewis number reduce the flow strength in the cavity.

Originality/value

There is no published study in the literature about sensitivity analysis of Brownian motion and thermophoresis force effects on the bioconvection heat transfer in a square cavity filled by both nanofluid and oxytactic microorganisms.

Details

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

Keywords

Article
Publication date: 20 September 2011

A.J. Chamkha, S.M.M. EL‐Kabeir and A.M. Rashad

The purpose of this paper is to consider heat and mass transfer by natural convection from a vertical cylinder in porous media for a temperature‐dependent fluid viscosity…

Abstract

Purpose

The purpose of this paper is to consider heat and mass transfer by natural convection from a vertical cylinder in porous media for a temperature‐dependent fluid viscosity in the presence of radiation and chemical reaction effects.

Design/methodology/approach

The governing equations are transformed into non‐similar differential equations and then solved numerically by an efficient finite‐difference method.

Findings

It is found that there are significant effects on the heat and mass transfer characteristics of the problem due to the variation of viscosity and radiation and chemical reaction effects.

Originality/value

The paper combines the effects of radiation, chemical reaction, non‐Darcy porous media effects along with the variation of viscosity with temperature.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 21 no. 7
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 2 March 2015

A Chamkha, S Abbasbandy and A.M. Rashad

The purpose of this paper is to investigate the effect of uniform lateral mass flux on non-Darcy natural convection of non-Newtonian fluid along a vertical cone embedded…

Abstract

Purpose

The purpose of this paper is to investigate the effect of uniform lateral mass flux on non-Darcy natural convection of non-Newtonian fluid along a vertical cone embedded in a porous medium filled with a nanofluid.

Design/methodology/approach

The resulting governing equations are non-dimensionalized and transformed into a non-similar form and then solved numerically by Keller box finite-difference method.

Findings

A comparison with previously published works is performed and excellent agreement is obtained.

Research limitations/implications

The model used for the nanofluid incorporates the effects of Brownian motion and thermophoresis. It is assumed that the cone surface is preamble for possible nanofluid wall suction/injection, under the condition of uniform heat and nanoparticles volume fraction fluxes.

Originality/value

The effects of nanofluid parameters, Ergun number, surface mass flux and viscosity index are investigated on the velocity, temperature, and volume fraction profiles as well as the local Nusselt and Sherwood numbers.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 25 no. 2
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 2 January 2020

A. Roja and B.J. Gireesha

Microfluidics is one of the extensive elaborated technologies in thermal and engineering fields due to its wide range of applications, such as micro heat exchangers, micro…

Abstract

Purpose

Microfluidics is one of the extensive elaborated technologies in thermal and engineering fields due to its wide range of applications, such as micro heat exchangers, micro mixture and microchannel heat sinks, which is used to develop a large number of microscopic devices and systems. Enhancement of thermal energy using verity of nanoliquids is one of the challenges in these applications of microfluidics. Therefore, using single wall carbon nanotubes for enhancement of thermal energy in microchannel is the main purpose of this study. Hall effect of natural convection flow in a vertical channel with slip and temperature jump condition is considered. The impacts of radiative heat flux, uniform heat source/sink, viscous dissipation and joule heating are also taken into account.

Design/methodology/approach

Suitable non-dimension variables are applied to the governing equations to reduce the system into ordinary differential equations. The reduced nonlinear system is then solved numerically using Runge–Kutta–Fehlberg fourth–fifth-order method along with shooting technique. The impact of different pertinent parameters on numerical solutions of primary velocity, secondary velocity, temperature, entropy generation and Bejan number is comprehensively discussed in detail. Also, the obtained numerical results are compared with existing one which perfectly found to be in good agreement.

Findings

It is established that, with the aspects of Joule heating, viscous dissipation, radiative heat flux and uniform heat source/sink, the production in the entropy can be improved. Further, it is found that the increasing ratio of wall ambient temperature difference and nanoparticle volume fraction leads to enhance the entropy generation. The same effect reverses with increasing values of fluid wall interaction parameter (FWIP) and rare faction. The irreversibility ratio enhances with larger values of nanoparticle volume fraction and decelerates with increment values of FWIP.

Originality/value

The impact of single wall carbon nanoliquid in a vertical channel flow by using radiative heat flux, heat source/sink, joule heating and viscous dissipation is first time investigated. Further, the influence of Hall current is explored in detail.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 30 no. 10
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 14 February 2018

Sreedevi Gandluru, Prasada Rao D.R.V. and O.D. Makinde

The purpose of this paper is to investigate the impact of thermal radiation interaction with Hall current, buoyancy force, and oscillatory surface temperature on…

Abstract

Purpose

The purpose of this paper is to investigate the impact of thermal radiation interaction with Hall current, buoyancy force, and oscillatory surface temperature on hydromagnetic-mixed convective heat exchange stream of an electrically conducting nanofluid past a moving permeable plate in a porous medium within a rotating system.

Design/methodology/approach

Analytical closed-form solutions are obtained for both the momentum and the energy equations using the perturbation method.

Findings

The effects of various important parameters on velocity and temperature fields within the boundary layer are discussed for three different water-based nanofluids containing copper (Cu), aluminum oxide (Al2O3), and titanium dioxide (TiO2) as nanoparticles. Local skin friction and Nusselt number are illustrated graphically and discussed quantitatively. The results show that Hall current significantly affects the flow system. Results for some special cases of the present analysis are in good agreement with the existing literature.

Originality/value

The problem is relatively original to study the hydromagnetic-oscillatory flow of a nanofluid with Hall effect and thermal radiation past a vertical plate in a rotating porous medium.

Details

Multidiscipline Modeling in Materials and Structures, vol. 14 no. 2
Type: Research Article
ISSN: 1573-6105

Keywords

Article
Publication date: 6 November 2018

Aurang Zaib, Rizwan Ul Haq, Ali J. Chamkha and Mohammad Mehdi Rashidi

The purpose of this paper is to present an inclusive study of the mixed convective flow involving micropolar fluid holding kerosene/water-based TiO2 nanoparticle towards a

Abstract

Purpose

The purpose of this paper is to present an inclusive study of the mixed convective flow involving micropolar fluid holding kerosene/water-based TiO2 nanoparticle towards a vertical Riga surface with partial slip. The outcomes are confined for opposing and assisting flows.

Design/methodology/approach

Similarity equations are acquired and then worked out numerically by the Keller box technique.

Findings

Impacts of significant parameters on microrotation velocity, temperature distribution, velocity profile together with the Nusselt number and the skin friction are argued with the help of graphs. Two solutions are achieved in opposing flow, while the solution is unique in assisting flow. It is also monitored that the separation of boundary layer delays because of micropolar parameter and accelerates because of volume fraction.

Originality/value

The authors trust that all these results are new and significant for researchers.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 29 no. 5
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 1 April 2014

A. Rashad and A. Chamkha

The purpose of this paper is to study the effects of chemical reaction, thermal radiation and Soret and Dufour effects of heat and mass transfer by natural convection flow…

Abstract

Purpose

The purpose of this paper is to study the effects of chemical reaction, thermal radiation and Soret and Dufour effects of heat and mass transfer by natural convection flow about a truncated cone in porous media.

Design/methodology/approach

The problem is formulated and solved numerically by an accurate implicit finite-difference method.

Findings

It is found that the Soret and Dufour effects as well as the thermal radiation and chemical reaction cause significant effects on the heat and mass transfer charateristics.

Originality/value

The problem is relatively original as it considers Soret and Dufour as well as chemical reaction and porous media effects on this type of problem.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 24 no. 3
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 29 August 2019

Abdelraheem M. Aly

This paper aims to adopt incompressible smoothed particle hydrodynamics (ISPH) method to simulate MHD double-diffusive natural convection in a cavity containing an

117

Abstract

Purpose

This paper aims to adopt incompressible smoothed particle hydrodynamics (ISPH) method to simulate MHD double-diffusive natural convection in a cavity containing an oscillating pipe and filled with nanofluid.

Design/methodology/approach

The Lagrangian description of the governing partial differential equations are solved numerically using improved ISPH method. The inner oscillating pipe is divided into two different pipes as an open and a closed pipe. The sidewalls of the cavity are cooled with a lower concentration C_c and the horizontal walls are adiabatic. The inner pipe is heated with higher concentration C_h. The analysis has been conducted for the two different cases of inner oscillating pipes under the effects of wide range of governing parameters.

Findings

It is found that a suitable oscillating pipe makes a well convective transport inside a cavity. Presence of the oscillating pipe has effects on the heat and mass transfer and fluid intensity inside a cavity. Hartman parameter suppresses the velocity and weakens the maximum values of the stream function. An increase on Hartman, Lewis and solid volume fraction parameters leads to an increase on average Nusselt number on an oscillating pipe and left cavity wall. Average Sherwood number on an oscillating pipe and left cavity wall decreases as Hartman parameter increases.

Originality/value

The main objective of this work is to study the MHD double-diffusive natural convection of a nanofluid in a square cavity containing an oscillating pipe using improved ISPH method.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 30 no. 2
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 15 October 2018

Aydin Zehforoosh, Siamak Hossainpour and Mohammad Mehdi Rashidi

The purpose of this study is to indicate the effect of mounting heat generating porous matrix in a close cavity on the Brownian term of CuO-water nanofluid and its impact…

Abstract

Purpose

The purpose of this study is to indicate the effect of mounting heat generating porous matrix in a close cavity on the Brownian term of CuO-water nanofluid and its impact on improving the Nusselt number.

Design/methodology/approach

Because of the presence of heat source in porous matrix, couple of energy equations is solved for porous matrix and nanofluid separately. Thermal conductivity and viscosity of nanofluid were assumed to be consisting of a static component and a Brownian component that were functions of volume fraction of the nanofluid and temperature. To explain the effect of the Brownian term on the flow and heat fields, different parameters such as heat conduction ratio, interstitial heat transfer coefficient, Rayleigh number, concentration of nanoparticles and porous material porosity were investigated and compared to those of the non-Brownian solution.

Findings

The Brownian term caused the cooling of porous matrix because of rising thermal conductivity. Mounting the porous material into cavity changes the temperature distribution and increases Brownian term effect and heat transfer functionality of the nanofluid. Besides, the effect of the Brownian term was seen to be greatest at low Rayleigh number, low-porosity and small thermal conductivity of the porous matrix. It is noteworthy that because of decrement of thermal conduction in high porosities, the impact of Brownian term drops severely making it possible to obtain reliable results even in the case of neglecting Brownian term in these porosities.

Originality/value

The effect of mounting the porous matrix with internal heat generation was investigated on the improvement of variable properties of nanofluid.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 29 no. 5
Type: Research Article
ISSN: 0961-5539

Keywords

1 – 10 of 295