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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: 1 August 2016

Hsien-Hung Ting and Shuhn-Shyurng Hou

The purpose of this paper is to numerically investigate the convective heat transfer of water-based CuO nanofluids flowing through a square cross-section duct under…

Abstract

Purpose

The purpose of this paper is to numerically investigate the convective heat transfer of water-based CuO nanofluids flowing through a square cross-section duct under constant heat flux in the turbulent flow regime.

Design/methodology/approach

The numerical simulation is carried out at various Peclet numbers and particle concentrations (0.1, 0.2, 0.5, and 0.8 vol%). The finite volume formulation is used with the semi-implicit method for pressure-linked equations algorithm to solve the discretized equations derived from the partial nonlinear differential equations of the mathematical model.

Findings

The heat transfer coefficients and Nusselt numbers of CuO-water nanofluids increase with increases in the Peclet number as well as particle volume concentration. Also, enhancement of the heat transfer coefficient is much greater than that of the effective thermal conductivity at the same nanoparticle concentration.

Research limitations/implications

Simulation of nanofluids turbulent forced convection at very high Reynolds number is worth for further study.

Practical implications

The heat transfer rates through non-circular ducts are smaller than the circular tubes. Nevertheless, the pressure drop of the non-circular duct is less than that of the circular tube. This study clearly presents that the nanoparticles suspended in water enhance the convective heat transfer coefficient, despite low volume fraction between 0.1 and 0.8 percent. Adding nanoparticles to conventional fluids may enhance heat transfer performance through the non-circular ducts, leading to extensive practical applications in industries for the non-circular ducts.

Originality/value

Few papers have numerically studied convective heat transfer properties of nanofluids through non-circular ducts. The present numerical results show a good agreement with the published experimental data.

Details

Engineering Computations, vol. 33 no. 6
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 1 May 2001

A.K. Satapathy and R.K. Sahoo

A numerical study has been made to investigate the effect of internal heating and precursory cooling during quenching of an infinite tube. The finite difference solution…

Abstract

A numerical study has been made to investigate the effect of internal heating and precursory cooling during quenching of an infinite tube. The finite difference solution gives the quench front temperature as a function of various model parameters such as Peclet number, Biot number and dimensionless heat flux. The parametric dependence of the rewetting rate is obtained by the condition that the surface can only be wetted when its temperature is below the quench front temperature. Also, the critical heat flux is obtained by setting Peclet number equal to zero, which gives the minimum heat flux required to prevent the hot surface being rewetted. The numerical model is validated by comparing the results with known closed form solutions.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 11 no. 3
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 2 March 2015

Noreen Sher Akbar

– The purpose of this paper is to discuss free convection peristaltic flow in an asymmetric channel with nanofluid containing gyrotactic microorganism.

Abstract

Purpose

The purpose of this paper is to discuss free convection peristaltic flow in an asymmetric channel with nanofluid containing gyrotactic microorganism.

Design/methodology/approach

The governing equations for proposed model are simplified using “long wavelength and low Reynolds number approximation.” Numerical solutions have been presented for “velocity, pressure gradient, the solid volume fraction nanoparticles, temperature profile and density of motile microorganisms.” The effects of various flow parameters, i.e Hartmann number, the solid volume fraction of the nanoparticles amplitude ratio, Prandtl number, bioconvection Péclet number, bioconvection constant, bioconvection Rayleigh number are presented.

Findings

The author finds that the pressure rise increases with an increase in Hartmann number, Grashof number bioconvection, Rayleigh number and buoyancy ratio in the peristaltic pumping section.

Originality/value

The peristaltic flow nanofluid containing gyrotactic microorganism is explored in the literature for the first time.

Details

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

Keywords

Article
Publication date: 16 September 2013

Anirban Bhattacharya and Pradip Dutta

In the present work, a numerical method, based on the well established enthalpy technique, is developed to simulate the growth of binary alloy equiaxed dendrites in…

Abstract

Purpose

In the present work, a numerical method, based on the well established enthalpy technique, is developed to simulate the growth of binary alloy equiaxed dendrites in presence of melt convection. The paper aims to discuss these issues.

Design/methodology/approach

The principle of volume-averaging is used to formulate the governing equations (mass, momentum, energy and species conservation) which are solved using a coupled explicit-implicit method. The velocity and pressure fields are obtained using a fully implicit finite volume approach whereas the energy and species conservation equations are solved explicitly to obtain the enthalpy and solute concentration fields. As a model problem, simulation of the growth of a single crystal in a two-dimensional cavity filled with an undercooled melt is performed.

Findings

Comparison of the simulation results with available solutions obtained using level set method and the phase field method shows good agreement. The effects of melt flow on dendrite growth rate and solute distribution along the solid-liquid interface are studied. A faster growth rate of the upstream dendrite arm in case of binary alloys is observed, which can be attributed to the enhanced heat transfer due to convection as well as lower solute pile-up at the solid-liquid interface. Subsequently, the influence of thermal and solutal Peclet number and undercooling on the dendrite tip velocity is investigated.

Originality/value

As the present enthalpy based microscopic solidification model with melt convection is based on a framework similar to popularly used enthalpy models at the macroscopic scale, it lays the foundation to develop effective multiscale solidification.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 23 no. 7
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 15 February 2021

Nirmalendu Biswas, Nirmal K. Manna, Dipak Kumar Mandal and Rama Subba Reddy Gorla

The purpose of this study is to address magnetohydrodynamic (MHD) bioconvection caused by the swimming of oxytactic microorganisms in a linearly heated square cavity…

Abstract

Purpose

The purpose of this study is to address magnetohydrodynamic (MHD) bioconvection caused by the swimming of oxytactic microorganisms in a linearly heated square cavity filled with porous media and Cu–water nanofluid. The effects of different multiphysical aspects are demonstrated using local distributions as well as global quantities for fluid flow, temperature, oxygen concentration and microorganisms population.

Design/methodology/approach

The coupled transport equations are converted into the nondimensional partial differential equations, which are solved numerically using a finite volume-based computing code. The flow of Cu–water nanofluid through the pores of porous media is formulated following the Brinkman–Forchheimer–Darcy model. The swimming of oxytactic microorganisms is handled following a continuum model.

Findings

The analysis of transport phenomena of bioconvection is performed in a linearly heated porous enclosure containing Cu–water nanofluid and oxytactic microorganisms under the influence of magnetic fields. The application of such a system could have potential impacts in diverse fields of engineering and science. The results show that the flow and temperature distribution along with the isoconcentrations of oxygen and microorganisms is markedly affected by the involved governing parameters.

Research limitations/implications

Similar study of bioconvection could be extended further considering thermal radiation, chemical attraction, gravity and light.

Practical implications

The outcomes of this investigation could be used in diverse fields of multiphysical applications, such as in food industries, chemical processing equipment, fuel cell technology and enhanced oil recovery.

Originality/value

The insight of the linear heating profile reveals a special attribute of simultaneous heating and cooling zones along the heated side. With such an interesting feature, the MHD bioconvection of oxytactic microorganisms in nanofluid-filled porous substance is not reported so far.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 31 no. 11
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 30 April 2019

Ali Belhocine and Wan Zaidi Wan Omar

This study aims to investigate numerically a two-dimensional fully developed mean turbulent fluid flow, and heat transfer in a circular duct is numerically investigated…

Abstract

Purpose

This study aims to investigate numerically a two-dimensional fully developed mean turbulent fluid flow, and heat transfer in a circular duct is numerically investigated using FORTRAN 95 code that applies the finite difference method to solve the thermal problem for the two thermal boundary conditions, constant surface temperature, constant heat and steady, axisymmetric flow. Several important results have been drawn and discussed from thermal analysis. Finally, the numerical results of the model developed in the document have been validated in good accuracy by comparing them with some correlation results available in the specialized literature.

Design/methodology/approach

The methodology of solving the thermal problem is based on the equation of energy for a fluid of constant properties while taking into consideration the hypothesis of the axisymmetric and fully developed pipe flow in steady state. The global equation and the initial and boundary conditions acting on the problem have been configured here in dimensionless form to predict the turbulent behavior of the fluid inside the tube. Thus, using Thomas' algorithm, a program in FORTRAN version 95 was developed to numerically solve the discretized form of the system of equations describing the problem.

Findings

The profiles of the solutions are provided from which the authors infer that the numerical and literature correlation agreed very well. Another result that they obtained from this study is the number of Nusselt in the thermal entrance region to which a parametric study based on Reynolds and Peclet numbers, and the longitudinal coordinate, was carried out and discussed well for the impact of the scientific contribution.

Originality/value

The novelty of the work is the application of the finite difference method programed on the FORTRAN code, as a sequential numerical method of an ODEs system, to determine the number of Nusselt in both uniform wall temperature and wall heat flux uniform.

Details

World Journal of Engineering, vol. 16 no. 2
Type: Research Article
ISSN: 1708-5284

Keywords

Article
Publication date: 2 January 2018

Dawid Taler

The purpose of this paper is to develop new semi-empirical heat transfer correlations for turbulent flow of liquid metals in the tubes, and then to compare these…

Abstract

Purpose

The purpose of this paper is to develop new semi-empirical heat transfer correlations for turbulent flow of liquid metals in the tubes, and then to compare these correlations with the experimental data. The Prandtl and Reynolds numbers can vary in the ranges: 0.0001 ≤ Pr ≤ 0.1 and 3000 ≤ Re ≤ 106.

Design/methodology/approach

The energy conservation equation averaged by Reynolds was integrated using the universal velocity profile determined experimentally by Reichardt for the turbulent tube flow and four different models for the turbulent Prandtl number. Turbulent heat transfer in the circular tube was analyzed for a constant heat flux at the inner surface. Some constants in different models for the turbulent Prandtl number were adjusted to obtain good agreement between calculated and experimentally obtained Nusselt numbers. Subsequently, new correlations for the Nusselt number as a function of a Peclet number was proposed for different models of the turbulent Prandtl number.

Findings

The inclusion of turbulent Prandtl number greater than one and the experimentally determined velocity profile of the fluid in the tube while solving the energy conservation equation improved the compatibility of calculated Nusselt numbers, with Nusselt numbers determined experimentally. The correlations proposed in the paper have a sound theoretical basis and give Nusselt number values that are in good agreement with the experimental data.

Research limitations/implications

Heat transfer correlations proposed in this paper were derived assuming a constant heat flux at the inner surface of the tube. However, they can also be used for a constant wall temperature, as for the turbulent flow (Re > 3,000), the relative difference between the Nusselt number for uniform wall heat flux and uniform wall temperature is very low.

Originality/value

Unified, systematic approach to derive correlations for the Nusselt number for liquid metals was proposed in the paper. The Nusselt number was obtained from the solution of the energy conservation equation using the universal velocity profile and eddy diffusivity determined experimentally, and various models for the turbulent Prandtl number. Four different relationships for the Nusselt number proposed in the paper were compared with the experimental data.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 28 no. 1
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 25 June 2019

Atul Kumar Ray, Vasu B., O. Anwar Beg, R.S.R. Gorla and P.V.S.N. Murthy

This paper aims to numerically investigate the two-dimensional unsteady laminar magnetohydrodynamic bioconvection flow and heat transfer of an electrically conducting…

Abstract

Purpose

This paper aims to numerically investigate the two-dimensional unsteady laminar magnetohydrodynamic bioconvection flow and heat transfer of an electrically conducting non-Newtonian Casson thin film with uniform thickness over a horizontal elastic sheet emerging from a slit in the presence of viscous dissipation. The composite effects of variable heat, mass, nanoparticle volume fraction and gyrotactic micro-organism flux are considered as is hydrodynamic (wall) slip. The Buongiorno nanoscale model is deployed which features Brownian motion and thermophoresis effects. The model studies the manufacturing fluid dynamics of smart magnetic bio-nano-polymer coatings.

Design/methodology/approach

The coupled non-linear partial differential boundary-layer equations governing the flow, heat and nano-particle and micro-organism mass transfer are reduced to a set of coupled non-dimensional equations using the appropriate transformations and then solved as an nonlinear boundary value problem with the semi-numerical Liao homotopy analysis method (HAM).Validation with a generalized differential quadrature (GDQ) numerical technique is included.

Findings

An increase in velocity slip results in a significant decrement in skin friction coefficient and Sherwood number, whereas it generates a substantial enhancement in Nusselt number and motile micro-organism number density. The computations reveal that the bioconvection Schmidt number decreases the micro-organism concentration and boundary-layer thickness which is attributable to a rise in viscous diffusion rate. Increasing bioconvection Péclet number substantially elevates the temperatures in the regime, thermal boundary layer thickness, nanoparticle concentration values and nano-particle species boundary layer thickness. The computations demonstrate the excellent versatility of HAM and GDQ in solving nonlinear multi-physical nano-bioconvection flows in thermal sciences and furthermore are relevant to application in the synthesis of smart biopolymers, microbial fuel cell coatings, etc.

Research limitations/implications

The numerical study is valid for two-dimensional, unsteady, laminar Casson film flow with nanoparticles over an elastic sheet in presence of variable heat, mass and nanoparticle volume fraction flux. The film has uniform thickness and flow is transpiring from slit which is fixed at origin.

Social implications

The study has significant applications in the manufacturing dynamics of nano-bio-polymers and the magnetic field control of materials processing systems. Furthermore, it is relevant to application in the synthesis of smart biopolymers, microbial fuel cell coatings, etc.

Originality/value

The originality of the study is to address the simultaneous effects of unsteady and variable surface fluxes on Casson nanofluid transport of gyrotactic bio-convection thin film over a stretching sheet in the presence of a transverse magnetic field. Validation of HAM with a GDQ numerical technique is included. The present numerical approaches (HAM and GDQ) offer excellent promise in simulating such multi-physical problems of interest in thermal thin film rheological fluid dynamics.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 29 no. 11
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 30 August 2022

G.K. Ramesh, J.K. Madhukesh, Emad H. Aly and Ioan Pop

The purpose of this paper is to study the steady biomagnetic hybrid nanofluid (HNF) of oxytactic microorganisms taking place over a thin needle with a magnetic field using…

Abstract

Purpose

The purpose of this paper is to study the steady biomagnetic hybrid nanofluid (HNF) of oxytactic microorganisms taking place over a thin needle with a magnetic field using the modified Buongiorno’s nanoliquid model.

Design/methodology/approach

On applying the appropriate similarity transformations, the governing partial differential equations were transformed into a set of ordinary differential equations. These equations have been then solved numerically using Runge–Kutta–Fehlberg method of fourth–fifth order programming in MAPLE software. Features of the velocity profiles, temperature distribution, reduced skin friction coefficient, reduced Nusselt number and microorganisms’ flux, for different values of the governing parameters were analyzed and discussed.

Findings

It was observed that as the needle thickness and solid volume fraction increase, the temperature rises, but the velocity field decreases. For a higher Peclet number, the motile microorganism curve increases, and for a higher Schmidt number, the concentration curve rises.

Originality/value

On applying the modified Buongiorno’s model, the present results are original and new for the study of HNF flow and heat transfer past a permeable thin needle.

Details

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

Keywords

1 – 10 of 285