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Article
Publication date: 20 June 2019

Shiyu Feng, Chaoyue Li, Xiaotian Peng, Lei Shao and Weihua Liu

The purpose of this study is to measure the mass diffusion coefficient of nitrogen in jet fuel using digital holography interferometry for cost-effective designing and…

Abstract

Purpose

The purpose of this study is to measure the mass diffusion coefficient of nitrogen in jet fuel using digital holography interferometry for cost-effective designing and modeling of the aircraft tank inerting system.

Design/methodology/approach

The mass diffusion coefficients of N2 in RP-3 and RP-5 jet fuels were measured by digital holography interferometry at temperatures ranging from 278.15 to 343.15 K. The Arrhenius equation is used to adequately describe the relationship between mass diffusion coefficients and temperature. The viscosities of RP-3 and RP-5 jet fuels were also measured to examine the accuracy of the Stokes–Einstein model in calculating mass diffusion coefficients.

Findings

As temperature increases from 278.15 to 343.15 K, the mass diffusion coefficients increase 4.23-fold for N2 in RP-3 jet fuel and 5.13-fold for N2 in RP-5 jet fuel. The value of Dµ/T is not constant as the Stokes–Einstein equation expressed, but is a weak linear function of temperature.

Practical implications

A more accurate diffusion model is proposed by fitting the measured Dµ/T with the temperature and calculating the mass diffusion coefficients of N2 in RP-3 and RP-5 jet fuels within 10 per cent relative deviation.

Originality/value

A measurement system for mass diffusion coefficients of N2 in RP-3 and RP-5 jet fuels was constructed based on the digital holography interferometry. The mass diffusion coefficient can be expressed by a uniform polynomial function of temperature and viscosity.

Details

Aircraft Engineering and Aerospace Technology, vol. 91 no. 8
Type: Research Article
ISSN: 1748-8842

Keywords

Content available
Article
Publication date: 27 August 2019

Mair Khan, T. Salahuddin, Muhammad Malik Yousaf, Farzana Khan and Arif Hussain

The purpose of the current flow configurations is to bring to attention the thermophysical aspects of magnetohydrodynamics (MHD) Williamson nanofluid flow under the…

Abstract

Purpose

The purpose of the current flow configurations is to bring to attention the thermophysical aspects of magnetohydrodynamics (MHD) Williamson nanofluid flow under the effects of Joule heating, nonlinear thermal radiation, variable thermal coefficient and activation energy past a rotating stretchable surface.

Design/methodology/approach

A mathematical model is examined to study the heat and mass transport analysis of steady MHD Williamson fluid flow past a rotating stretchable surface. Impact of activation energy with newly introduced variable diffusion coefficient at the mass equation is considered. The transport phenomenon is modeled by using highly nonlinear PDEs which are then reduced into dimensionless form by using similarity transformation. The resulting equations are then solved with the aid of fifth-order Fehlberg method.

Findings

The rotating fluid, heat and mass transport effects are analyzed for different values of parameters on velocity, energy and diffusion distributions. Parameters like the rotation parameter, Hartmann number and Weissenberg number control the flow field. In addition, the solar radiation, Joule heating, Prandtl number, thermal conductivity, concentration diffusion coefficient and activation energy control the temperature and concentration profiles inside the stretching surface. It can be analyzed that for higher values of thermal conductivity, Eckret number and solar radiation parameter the temperature profile increases, whereas opposite behavior is noticed for Prandtl number. Moreover, for increasing values of temperature difference parameter and thermal diffusion coefficient, the concentration profile shows reducing behavior.

Originality/value

This paper is useful for researchers working in mathematical and theoretical physics. Moreover, numerical results are very useful in industry and daily-use processes.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 30 no. 5
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 6 March 2017

Zbigniew Bulinski and Helcio R.B. Orlande

This paper aims to present development and application of the Bayesian inverse approach for retrieving parameters of non-linear diffusion coefficient based on the integral…

Abstract

Purpose

This paper aims to present development and application of the Bayesian inverse approach for retrieving parameters of non-linear diffusion coefficient based on the integral information.

Design/methodology/approach

The Bayes formula was used to construct posterior distribution of the unknown parameters of non-linear diffusion coefficient. The resulting aposteriori distribution of sought parameters was integrated using Markov Chain Monte Carlo method to obtain expected values of estimated diffusivity parameters as well as their confidence intervals. Unsteady non-linear diffusion equation was discretised with the Global Radial Basis Function Collocation method and solved in time using Crank–Nicholson technique.

Findings

A number of manufactured analytical solutions of the non-linear diffusion problem was used to verify accuracy of the developed inverse approach. Reasonably good agreement, even for highly correlated parameters, was obtained. Therefore, the technique was used to compute concentration dependent diffusion coefficient of water in paper.

Originality/value

An original inverse technique, which couples efficiently meshless solution of the diffusion problem with the Bayesian inverse methodology, is presented in the paper. This methodology was extensively verified and applied to the real-life problem.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 27 no. 3
Type: Research Article
ISSN: 0961-5539

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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

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Article
Publication date: 1 May 2000

Vítor Geraldes, Viriato Semião and Maria Norberta Pinho

A mathematical model to predict the concentration polarisation in nanofiltration/reverse osmosis is described. It incorporates physical modelling for mass transfer…

Abstract

A mathematical model to predict the concentration polarisation in nanofiltration/reverse osmosis is described. It incorporates physical modelling for mass transfer, laminar hydrodynamics and the membrane rejection coefficient. The SIMPLE algorithm solves the discretised equations derived from the governing differential equations. The convection and diffusive terms of those equations are discretised by the upwind, the hybrid and the exponential schemes for comparison purposes. The hybrid scheme appears as the most suitable one for the type of flows studied herein. The model is first applied to predict the concentration polarisation in a slit, for which mathematical solutions for velocities and concentrations exist. Different grids are used within the hybrid scheme to evaluate the model sensitivity to the grid refinement. The 55×25 grid results agree excellently for engineering purposes with the known solutions. The model, incorporating a variation law for the membrane intrinsic rejection coefficient, was also applied to the predictions of a laboratory slit where experiments are performed and reported, yielding excellent results when compared with the experiments.

Details

Engineering Computations, vol. 17 no. 3
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 30 July 2019

Basant Kumar Jha and Muhammad Nasir Sarki

The purpose of this paper is to conduct a theoretical study on steady fully developed non-linear natural convection and mass transfer flow past an infinite vertical moving…

Abstract

Purpose

The purpose of this paper is to conduct a theoretical study on steady fully developed non-linear natural convection and mass transfer flow past an infinite vertical moving porous plate with chemical reaction and thermal diffusion effect. Closed-form expressions for dimensionless velocity, concentration, Sherwood number and skin-friction are obtained by solving the present mathematical model.

Design/methodology/approach

The fully developed steady non-linear natural convection and mass transfer flow near a vertical moving porous plate with chemical reaction and thermal diffusion effect is investigated. The non-linear density variation and Soret effect were taken into consideration. The dimensionless velocity, temperature and concentration profiles were obtained in terms of exponential functions, and were used to compute the governing parameters, skin-friction and Sherwood number.

Findings

The effect of coefficient of the non-linear density variation with the temperature (NDT) and concentration (NDC) parameter, chemical reaction parameter, thermal diffusion parameter are discussed with the aid of line graphs and tables. The analysis of the result shows that the velocity as well as skin-friction having higher values in the case of non-linear variation of density with temperature and concentration in comparison to linear variation of density with temperature and concentration. It is observed that the velocity and skin-friction increase with an increase in the Soret parameter.

Originality/value

The aim of this paper is to extend the work of Muthucumaraswamy (2002) by incorporating the thermal diffusion (Soret) effect and non-linear density variation with temperature (NDT) and concentration (NDC), on which, to the best knowledge of the authors, no studies have been carried out.

Details

Multidiscipline Modeling in Materials and Structures, vol. 15 no. 5
Type: Research Article
ISSN: 1573-6105

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Article
Publication date: 1 March 1997

S. Sundarraj and V.R. Voller

Explains that segregation processes during the solidification of a binary alloy occur at two distinct length scales: on the microscopic length scale of the crystal…

Abstract

Explains that segregation processes during the solidification of a binary alloy occur at two distinct length scales: on the microscopic length scale of the crystal interface, in the two‐phase mushy zone, segregation is controlled by solid state mass diffusion; and, on the macroscopic scale of the process, segregation is controlled by the convective transport of the molten metal. Concludes that developing models that can capture both these scales is a challenge. Introduces a bi‐level grid, and uses a macro grid on the scale of the process for the solution of equations describing macroscopic heat and mass transport. Details how each node point in the macro grid is associated with a micro grid on which equations describing the microscopic phenomena in the mushy region are solved. In this way, develops a dual‐scale model of segregation during the solidification of a binary alloy. On investigating the unidirectional solidification of a binary alloy, demonstrates that this dual‐scale model is able to capture both the macro and micro‐scales in a single numerical treatment.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 7 no. 2/3
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 15 May 2009

Dipankar Chatterjee and Suman Chakraborty

The purpose of this paper is to carry out a systematic energy analysis for predicting the first and second law efficiencies and the entropy generation during a laser…

Abstract

Purpose

The purpose of this paper is to carry out a systematic energy analysis for predicting the first and second law efficiencies and the entropy generation during a laser surface alloying (LSA) process.

Design/methodology/approach

A three‐dimensional transient macroscopic numerical model is developed to describe the turbulent transport phenomena during a typical LSA process and subsequently, the energy analysis is carried out to predict the entropy generation as well as the first and second law efficiencies. A modified k–ε model is used to address turbulent molten metal‐pool convection. The phase change aspects are addressed using a modified enthalpy‐porosity technique. A kinetic theory approach is adopted for modelling evaporation from the top surface of the molten pool.

Findings

It is found that the heat transfer due to the strong temperature gradient is mainly responsible for the irreversible degradation of energy in the form of entropy production and the flow and mass transfer effects are less important for this type of phase change problem. The first and second law efficiencies are found to increase with effective heat input and remain independent of the powder feed rate. With the scanning speed, the first law efficiency increases whereas the second law efficiency decreases.

Research limitations/implications

The top surface undulations are not taken care of in this model which is a reasonable approximation.

Practical implications

The results obtained will eventually lead to an optimized estimation of laser parameters (such as laser power, scanning speed, etc.), which in turn improves the process control and reduces the cost substantially.

Originality/value

This paper provides essential information for modelling solid–liquid phase transition as well as a systematic analysis for entropy generation prediction.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 19 no. 3/4
Type: Research Article
ISSN: 0961-5539

Keywords

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Article
Publication date: 5 May 2021

Shahin Akbari, Nima Hasanvand, Sadegh Sadeghi, Mehdi Bidabadi and Qingang Xiong

The widespread usage of magnetic nanoparticles (MNPs) requires their efficient synthesis during combustion process. This study aims to present a mathematical model for the…

Abstract

Purpose

The widespread usage of magnetic nanoparticles (MNPs) requires their efficient synthesis during combustion process. This study aims to present a mathematical model for the oxidation of MNPs in a counter-flow non-premixed combustion system to produce MNPs, where the key sub-processes during the oxidation reaction are involved.

Design/methodology/approach

To accurately describe structure of flame and determine distributions of temperature and mass fractions of both reactants and products, equations of energy and mass conservations were solved based on the prevailing assumptions that three regions, i.e. preheating, reaction and oxidizer zones exist.

Findings

The numerical simulation was first validated against experimental data and characteristics of the combustion process are discussed. Eventually, the influences of crucial parameters such as reactant Lewis numbers, strain rate ratio, particle size, inert gas and thermophoretic force on structure of flame and combustion behavior were examined. The results show that maximum flame temperature can achieve 2,205 K. Replacing nitrogen with argon and helium as carrier gases can increase flame temperature by about 27% and 34%, respectively. Additionally, maximum absolute thermophoretic force was found at approximately 9.6 × 10–8 N.

Originality/value

To the best of authors’ knowledge, this is the first time to numerically model the preparation of MNPs in a counter-flow non-premixed combustion configuration, which can guide large-scale experimental work in a more effective way.

Details

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

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Article
Publication date: 6 November 2017

Guanhui Wang, Lin Xiao, Tiantian Nan, Jin Jia, Haiying Xiao and Dongxing Zhang

This study aimed to investigate the collective effects of bending load and hygrothermal aging on glass fibre-reinforced plastics (GFRP) due to the fact that stress and…

Abstract

Purpose

This study aimed to investigate the collective effects of bending load and hygrothermal aging on glass fibre-reinforced plastics (GFRP) due to the fact that stress and water absorption is inevitable during GFRP applications.

Design/methodology/approach

The water boiling method was used to study the moisture absorption, desorption behaviour and evaluate the performance of GFRP laminates under loading in this article. The moisture diffusion of laminates is characterized in three aging conditions (25°C, 45°C and 65°C water), along with three levels of bending load coefficients (0, 0.3 and 0.6). The moisture diffusion coefficients are determined through the curve fitting method of the experimental data of the initial process, based on the Fickian diffusion model. Moreover, the laminates’ performance is further discussed after adequate environmental aging and loading.

Findings

It was found that moisture absorption is promoted by the presence of bending load and boiling during this study. The absorption diffusion coefficient and moisture equilibrium content of the specimens increased with an increasing loading ratio and temperature. The bending strength of the laminate varied according to a contrary trend. Furthermore, the desorbed moisture content is found to be much higher after higher levels of bending load because it is harder to desorb the moisture in the interfaces and micro cracks.

Research limitations/implications

Collective effects of bending load and hygrothermal aging promote the absorption and result in accelerating property degradation of GFRP. It is significant to focus on these effects on the failure of GFRP.

Originality/value

A novel unit was designed to simulate the various loading acted on containers in this work.

Details

Pigment & Resin Technology, vol. 46 no. 6
Type: Research Article
ISSN: 0369-9420

Keywords

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