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Article
Publication date: 7 June 2019

Reza Dadsetani, Ghanbar Ali Sheikhzadeh, Mohammad Reza Hajmohammadi and Mohammad Reza Safaei

Electronic components’ efficiency is the cornerstone of technology progress. The cooling process used for electronic components plays a main role in their performance…

Abstract

Purpose

Electronic components’ efficiency is the cornerstone of technology progress. The cooling process used for electronic components plays a main role in their performance. Embedded high-conductivity material and provided microchannel heat sink are two common cooling methods. The former is expensive to implement while the latter needs micro-pump, which consumes energy to circulate the flow. The aim of this study is providing a new configuration and method for improving the performance of electronic components.

Design/methodology/approach

To manage these challenges and improve the cooling efficiency, a novel method named Hybrid is presented here. Each method's performance has been investigated, and the results are widely compared with others. Considering the micro-pump power, the supply of the microchannel flow and the thermal conductivity ratio (thermal conductivity ratio is defined as the ratio of thermal conductivity of high thermal conductivity material to the thermal conductivity of base solid), the maximum disk temperature of each method was evaluated and compared to others.

Findings

The results indicated that the Hybrid method can reduce the maximum disk temperature up to 90 per cent compared to the embedded high thermal conductivity at the same thermal conductivity ratio. Moreover, the Hybrid method further reduces the maximum disk temperature up to 75 per cent compared to the microchannel, at equivalent power consumption.

Originality/value

The information in this research is presented in such a way that designers can choose the desired composition, the limited amount of consumed energy and the high temperature of the component. According to the study of radial-hybrid configuration, the different ratio of microchannel and materials with a high thermal conductivity coefficient in the constant cooling volume was investigated. The goal of the investigation was to decrease the maximum temperature of a plate on constant energy consumption. This aim has been obtained in the radial-hybrid configuration.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 30 no. 6
Type: Research Article
ISSN: 0961-5539

Keywords

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Abstract

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 30 no. 1
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 19 July 2019

Hamid Reza Goshayeshi and Mohammad Reza Safaei

Solar-driven water desalination technologies are rapidly developing with various links to other renewable sources. However, the efficiency of such systems severely depends…

Abstract

Purpose

Solar-driven water desalination technologies are rapidly developing with various links to other renewable sources. However, the efficiency of such systems severely depends on the design parameters. This paper presents results from an investigation on the effect of the glass cover inclination angle on the performance of two stepped solar still geometries (flat and convex) and the amount of produced distilled water.

Design Methodology Approach

Studied inclination angles of 25°, 27.5°, 30°, 32.5° and 35° were chosen, while other design parameters were fixed.

Findings

The investigation showed that the unit with the convex absorber plate had higher average water daily production rate, compared to the output of the flat absorber plate unit. The results also depicted that the inclination angle of the still has a noticeable effect on the performance of solar stills. The value of the critical angle is 32.5°, and the higher inclination angle results in less heat transfer coefficient. This value can be used for design purposes and erases the typical assumption to use lower angles to optimize the productivity of the still.

Practical Implications

Finally, obtained data were used to correlate the Nusselt number for the flat and convex surfaces with different inclination angles of the glass cover.

Originality Value

The outcome of this investigation may find applications to develop highly efficient solar stills to secure more drinkable water in warm, dry lands.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 30 no. 6
Type: Research Article
ISSN: 0961-5539

Keywords

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Article
Publication date: 22 March 2021

Iman Mazinani, Mohammad Mohsen Sarafraz, Zubaidah Ismail, Ahmad Mustafa Hashim, Mohammad Reza Safaei and Somchai Wongwises

Two disastrous Tsunamis, one on the west coast of Sumatra Island, Indonesia, in 2004 and another in North East Japan in 2011, had seriously destroyed a large number of…

Abstract

Purpose

Two disastrous Tsunamis, one on the west coast of Sumatra Island, Indonesia, in 2004 and another in North East Japan in 2011, had seriously destroyed a large number of bridges. Thus, experimental tests in a wave flume and a fluid structure interaction (FSI) analysis were constructed to gain insight into tsunami bore force on coastal bridges.

Design/methodology/approach

Various wave heights and shallow water were used in the experiments and computational process. A 1:40 scaled concrete bridge model was placed in mild beach profile similar to a 24 × 1.5 × 2 m wave flume for the experimental investigation. An Arbitrary Lagrange Euler formulation for the propagation of tsunami solitary and bore waves by an FSI package of LS-DYNA on high-performance computing system was used to evaluate the experimental results.

Findings

The excellent agreement between experiments and computational simulation is shown in results. The results showed that the fully coupled FSI models could capture the tsunami wave force accurately for all ranges of wave heights and shallow depths. The effects of the overturning moment, horizontal, uplift and impact forces on a pier and deck of the bridge were evaluated in this research.

Originality/value

Photos and videos captured during the Indian Ocean tsunami in 2004 and the 2011 Japan tsunami showed solitary tsunami waves breaking offshore, along with an extremely turbulent tsunami-induced bore propagating toward shore with significantly higher velocity. Consequently, the outcomes of this current experimental and numerical study are highly relevant to the evaluation of tsunami bore forces on the coastal, over sea or river bridges. These experiments assessed tsunami wave forces on deck pier showing the complete response of the coastal bridge over water.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 31 no. 5
Type: Research Article
ISSN: 0961-5539

Keywords

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Article
Publication date: 25 June 2019

Marjan Goodarzi, Iskander Tlili, Zhe Tian and Mohammad Reza Safaei

This study aims to model the nanofluid flow in microchannel heat sinks having the same length and hydraulic diameter but different cross-sections (circular, trapezoidal…

Abstract

Purpose

This study aims to model the nanofluid flow in microchannel heat sinks having the same length and hydraulic diameter but different cross-sections (circular, trapezoidal and square).

Design/methodology/approach

The nanofluid is graphene nanoplatelets-silver/water, and the heat transfer in laminar flow was investigated. The range of coolant Reynolds number in this investigation was 200 ≤ Re ≤ 1000, and the concentrations of nano-sheets were from 0 to 0.1 vol. %.

Findings

Results show that higher temperature leads to smaller Nusselt number, pressure drop and pumping power, and increasing solid nano-sheet volume fraction results in an expected increase in heat transfer. However, the influence of temperature on the friction factor is insignificant. In addition, by increasing the Reynolds number, the values of pressure drop, pumping power and Nusselt number augments, but friction factor diminishes.

Research limitations/implications

Data extracted from a recent experimental work were used to obtain thermo-physical properties of nanofluids.

Originality/value

The effects of temperature, microchannel cross-section shape, the volume concentration of nanoparticles and Reynolds number on thermal and hydraulics behavior of the nanofluid were investigated. Results are presented in terms of velocity, Nusselt number, pressure drop, friction loss and pumping power in various conditions. Validation of the model against previous papers showed satisfactory agreement.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 30 no. 1
Type: Research Article
ISSN: 0961-5539

Keywords

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Article
Publication date: 7 June 2019

Kamel Hooman, Mohammad Reza Safaei, Hussein Togun and Mahidzal Dahari

In this study, closed-form solutions are presented to investigate thermohydraulics of liquid films in a rotating heat pipe. The film thickness is expressed as a function…

Abstract

Purpose

In this study, closed-form solutions are presented to investigate thermohydraulics of liquid films in a rotating heat pipe. The film thickness is expressed as a function of flow rate.

Design/methodology/approach

Further, sensitivity of both film thickness and flow rate to the length of the rotating heat pipe can now be investigated using the explicit expressions presented here.

Findings

To make it easier for practical application, an approximate solution is presented on top of the exact solution.

Originality/value

Both approximate and exact solutions are then applied to note that results are in good agreement when compared to those available in the literature.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 30 no. 6
Type: Research Article
ISSN: 0961-5539

Keywords

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Article
Publication date: 9 June 2021

Nur Husnina Saadun, Nurul Aini Jaafar, Md Faisal Md Basir, Ali Anqi and Mohammad Reza Safaei

The purpose of this study is to solve convective diffusion equation analytically by considering appropriate boundary conditions and using the Taylor-Aris method to…

Abstract

Purpose

The purpose of this study is to solve convective diffusion equation analytically by considering appropriate boundary conditions and using the Taylor-Aris method to determine the solute concentration, the effective and relative axial diffusivities.

Design/methodology/approach

>An analysis has been conducted on how body acceleration affects the dispersion of a solute in blood flow, which is known as a Bingham fluid, within an artery. To solve the system of differential equations analytically while validating the target boundary conditions, the blood velocity is obtained.

Findings

The blood velocity is impacted by the presence of body acceleration, as well as the yield stress associated with Casson fluid and as such, the process of dispersing the solute is distracted. It graphically illustrates how the blood velocity and the process of solute dispersion are affected by various factors, including the amplitude and lead angle of body acceleration, the yield stress, the gradient of pressure and the Peclet number.

Originality/value

It is witnessed that the blood velocity, the solute concentration and also the effective and relative axial diffusivities experience a drop when either of the amplitude, lead angle or the yield stress rises.

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

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Article
Publication date: 7 June 2019

Masoud Mozaffari, Annunziata D’Orazio, Arash Karimipour, Ali Abdollahi and Mohammad Reza Safaei

The purpose of this paper is to improve the lattice Boltzmann method’s ability to simulate a microflow under constant heat flux.

Abstract

Purpose

The purpose of this paper is to improve the lattice Boltzmann method’s ability to simulate a microflow under constant heat flux.

Design/methodology/approach

Develop the thermal lattice Boltzmann method based on double population of hydrodynamic and thermal distribution functions.

Findings

The buoyancy forces, caused by gravity, can change the hydrodynamic properties of the flow. As a result, the gravity term was included in the Boltzmann equation as an external force, and the equations were rewritten under new conditions.

Originality/value

To the best of the authors’ knowledge, the current study is the first attempt to investigate mixed-convection heat transfer in an inclined microchannel in a slip flow regime.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 30 no. 6
Type: Research Article
ISSN: 0961-5539

Keywords

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Article
Publication date: 13 June 2019

Zhe Tian, Seyed Amin Bagherzadeh, Kamal Ghani, Arash Karimipour, Ali Abdollahi, Mehrdad Bahrami and Mohammad Reza Safaei

This paper aims to propose a new nonlinear function estimation fuzzy system as a novel statistical approach to estimate nanofluids’ thermal conductivity.

Abstract

Purpose

This paper aims to propose a new nonlinear function estimation fuzzy system as a novel statistical approach to estimate nanofluids’ thermal conductivity.

Design/methodology/approach

A fuzzy system having a product inference engine, a singleton fuzzifier, a center average defuzzifier and Gaussian membership functions is proposed for this purpose.

Findings

Results indicate that the proposed fuzzy system can predict the thermal conductivity of Al2O3/paraffin nanofluid with appropriate precision and generalization and it also outperforms the classic interpolation methods.

Originality/value

A new nonlinear function estimation fuzzy system was introduced as a novel statistical approach to estimate nanofluids’ thermal conductivity for the first time.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 30 no. 6
Type: Research Article
ISSN: 0961-5539

Keywords

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Article
Publication date: 24 February 2020

Rahmat Ellahi, Ahmad Zeeshan, Farooq Hussain and Mohammad Reza Safaei

The purpose of this study is to investigate the monodisperse cavitation of bubbly mixture flow for water and hydrogen mixture flows through a nozzle having a stenosis on the wall.

Abstract

Purpose

The purpose of this study is to investigate the monodisperse cavitation of bubbly mixture flow for water and hydrogen mixture flows through a nozzle having a stenosis on the wall.

Design/methodology/approach

Two flow regions, namely, quasi-statically stable and quasi-statically unstable increase in the bubble radius, are considered. Different oscillating periods of bubbles in downstream corresponding to various values of Reynolds number are taken into account. The Range–Kutta method is used to tackle nonlinear coupled system of governing equations.

Findings

It is observed that for the larger values of Reynolds number, the void fraction at the upstream section, even at small values, yields instabilities at the downstream. Consequently, owing to sudden increase in the velocity, the bubbles strike the wall with high speed that eventually remove the existing stenosis. This process can be considered as an effective cardiac surgery for arteries with semi-blockage.

Originality/value

Original research work and to the best of author’s knowledge, this model is reported for the first time.

Details

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

Keywords

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