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This paper aims to measure the sensitivity of the structure’s deformation numerical model (NM) related to the various types of the design parameters, which is a suitable method for parameter selection to increase the time of model-updating.

In this research, a variance-based sensitivity analysis (VBSA) approach is proposed to measure the sensitivity of NM of structures. In this way, the contribution of measurements of the structure (such as design parameter values and geometry) on the output of NM is studied using first-order and total-order sensitivity indices developed by Sobol’. In this way the generated data set of parameters by considering different distributions such as Gaussian or uniform distribution and different order as input along with, the resulted deformation variables of NM as output has been submitted to the Sobol’ indices estimation procedure. To the verification of VBSA results, a gradient-based sensitivity analysis (SA), which is developed as a global SA method has been developed to measure the global sensitivity of NM then implemented over the NM’s results of a tunnel.

Regarding the estimated indices, it has been concluded that the derived deformation functions from the tunnel’s NM usually are non-additive. Also, some parameters have been determined as most effective on the deformation functions, which can be selected for model-updating to avoid a time-consuming process, so those may better to be considered in the group of updating parameters. In this procedure for SA of the model, also some interactions between the selected parameters with other parameters, which are beneficial to be considered in the model-updating procedure, have been detected. In this study, some parameters approximately (27 per cent of the total) with no effect over the all objective functions have been determined to be excluded from the parameter candidates for model-updating. Also, the resulted indices of implemented VBSA were approved during validation by the gradient-based indices.

The introduced method has been implemented for a circular lined tunnel’s NM, which has been created by Fast Lagrangian Analysis of Continua software.

This paper plans to apply a statistical method, which is global on the results of the NM of a soil structure by a complex system for parameter selection to avoid the time-consuming model-updating process.

Although many studies have been conducted on the nanofluid flow in microtubes, this paper, for the first time, aims to investigate the effects of nanoparticle diameter and concentration on the velocity and temperature fields of turbulent non-Newtonian Carboxymethylcellulose (CMC)/copper oxide (CuO) nanofluid in a three-dimensional microtube. Modeling has been done using low- and high-Reynolds turbulent models. CMC/CuO was modeled using power law non-Newtonian model. The authors obtained interesting results, which can be helpful for engineers and researchers that work on cooling of electronic devices such as LED, VLSI circuits and MEMS, as well as similar devices.

Present numerical simulation was performed with finite volume method. For obtaining higher accuracy in the numerical solving procedure, second-order upwind discretization and SIMPLEC algorithm were used. For all Reynolds numbers and volume fractions, a maximum residual of 10⁻⁶ is considered for saving computer memory usage and the time for the numerical solving procedure.

In constant Reynolds number and by decreasing the diameter of nanoparticles, the convection heat transfer coefficient increases. In Reynolds numbers of 2,500, 4,500 and 6,000, using nanoparticles with the diameter of 25 nm compared with 50 nm causes 0.34 per cent enhancement of convection heat transfer coefficient and Nusselt number. Also, in Reynolds number of 2,500, by increasing the concentration of nanoparticles with the diameter of 25 nm from 0.5 to 1 per cent, the average Nusselt number increases by almost 0.1 per cent. Similarly, In Reynolds numbers of 4,500 and 6,000, the average Nusselt number increases by 1.8 per cent.

The numerical simulation was carried out for three nanoparticle diameters of 25, 50 and 100 nm with three Reynolds numbers of 2,500, 4,500 and 6,000. Constant heat flux is on the channel, and the inlet fluid becomes heated and exists from it.

The authors obtained interesting results, which can be helpful for engineers and researchers that work on cooling of electronic devices such as LED, VLSI circuits and MEMS, as well as similar devices.

This manuscript is an original work, has not been published and is not under consideration for publication elsewhere. About the competing interests, the authors declare that they have no competing interests.

In the present study, laminar steady flow of nanofluid through a trapezoidal channel is studied by using of finite volume method. The main aim of this paper is to study the effect of changes in geometric parameters, including internal and external dimensions on the behavior of heat transfer and fluid flow. For each parameter, an optimum ratio will be presented.

The results showed that in a channel cell, changing any geometric parameter may affect the temperature and flow field, even though the volume of the channel is kept constant. For a relatively small hydraulic diameter, microchannels with different angles have a similar dimensionless heat flux, while channels with bigger dimensions show various values of dimensionless heat flux. By increasing the angles of trapezoidal microchannels, dimensionless heat flux per unit of volume increases. As a result, the maximum and minimum heat transfer rate occurs in a trapezoidal microchannel with 75° and 30 internal’s, respectively. In the study of dimensionless heat flux rate with hydraulic diameter variations, an optimum hydraulic diameter (Dh) was observed in which the heat transfer rate per unit volume attains maximum value.

This optimum state is predicted to happen at a side angle of 75° and hydraulic diameter of 290 µm. In addition, in trapezoidal microchannel with higher aspect ratio, dimensionless heat flux rate is lower. Changing side angles of the channels and pressure drop have the same effect on pressure drop. For a constant pressure drop, if changing the side angles causes an increase in the rectangular area of the channel cross-section and the effect of the sides are not felt by the fluid, then the dimensionless heat flux will increase. By increasing the internal aspect ratio (t_2/t_3), the amount of t_3 decreases, and consequently, the conduction resistance of the hot surface decreases.

The effects of geometry of the microchannel, including internal and external dimensions on the behavior of heat transfer and fluid flow for pressure ranges between 2 and 8 kPa.

The purpose of this study is numerical simulation of magnetohydrodynamics (MHD) water–Al₂O₃ nanofluid mixed convection in a grooved channel with internal heat generation in solid cylinders. Simulations were carried out at Reynolds numbers 50 ≤ Re ≤ 100, Hartmann numbers 0 ≤ Ha ≤ 15, Grashof numbers 5,000 ≤ Gr ≤ 10⁻⁴ and volume fraction 0 ≤ φ ≤ 0.04. The effect of Reynolds number and the influence of magnetic field and pressure drop on convective heat transfer coefficient were studied in different volume fractions of nanoparticles at different Reynolds numbers.

The results show that average Nusselt number increases by increasing Reynolds and Hartman numbers. Also, when Hartman number increases, velocity profile becomes asymmetric. Pressure distribution shows that magnetic field applies Lorentz force at opposite direction of the flow, which causes asymmetric distribution of pressure. As a result, pressure in the upper half of the cylinder is higher than the lower half. Finally, velocity and temperature contours along the channel for different Hartmann numbers, volume fraction 3 per cent, Re = 50 and 100 and Gr = 10,000, are presented.

The effect of Reynolds number and the influence of magnetic field and pressure drop on convective heat transfer coefficient were studied in different volume fractions of nanoparticles at different Reynolds numbers.

Effect of MHD on the flow and heat transfer characteristics of Water–Al₂O₃ nanofluid in a grooved channel with internal heat generation in solid cylinders.

In this paper, the forced convection heat transfer of the nanofluid composed of water and AL2O3 nanoparticles is simulated in a two-dimensional horizontal microchannel by injecting the lower wall. The upper wall of the microchannel is 303 K at temperature TH. On the lower wall of the microchannel, there are three holes for flow injection. Other parts of the wall are insulated. In this paper, the effect of parameters such as Reynolds number, slip coefficient and volume fraction of nanoparticles is investigated.

The boundary condition of the slip velocity is considered on the upper and lower walls of the microchannel. In this work, the flow of nanofluid in the microchannel is considered to be slow, permanent and Newtonian. In the present study, the effect of injection through the microchannel wall on the slip velocity is examined for the first time.

The results are also presented as velocity profiles and Nusselt number diagrams. It was found that the Nusselt number increases with increasing the amount of slip coefficient of velocity and the weight percentage of solid nanoparticles. The rate of this increase is higher in the high values of the Reynolds number.

A novel paper concerned the simulation of cross-flow injection effects on the slip velocity and temperature domain of a nanofluid flow inside a microchannel.

With respect to two new subjects, i.e. nanofluids and microchannels, in heat transfer systems and modern techniques used for building them, this paper aims to study on effect of using aluminum oxide nanoparticles in non-Newtonian fluid of aqueous solution of carboxy-methyl cellulose in microtube and through application of different slip coefficients to achieve various qualities on surface of microtube.

Simultaneously, the effect of presence of nanoparticles and phenomenon of slip and temperature jump has been explored in non-Newtonian nanofluid in this essay. The assumption of homogeneity of nanofluid and fixed temperature of wall in microtube has been used in modeling processes.

The results have been presented as diagrams of velocity, temperature and Nusselt Number and the investigations have indicated that addition of nanoparticles to the base fluid and increase in microtube slip coefficient might improve rate of heat transfer in microtube.

The flow of non-Newtonian nanofluid of aqueous solution of carboxy methyl cellulose-aluminum oxide has been determined in a microtube for the first time.

Porous medium has always been introduced as an environment for increasing heat transfer in cooling systems. However, increase in heat transfer and resolving pressure drop in the fluid flow have been focused on by researchers.The purpose of this paper is to study the effects of creating porous micro-channels inside porous macro-blocks to optimize system performance in channels.

To simulate flow field, a developed numerical code that solves Navier–Stokes equations by finite volume method and semi-implicit method for pressure linked equations (SIMPLE) algorithm will be used together with bi-disperse porous medium (BDPM) method. Working fluid is air with Pr = 0.7 in laminar state. Influence of permeability changes by creation of micro-channels containing porous medium in vertical, horizontal and cross-shape patterns will be investigated.

By creating porous micro-channels inside macro-blocks, not only does the heat transfer increase significantly but the pressure also drops remarkably. Increase in performance evaluation criteria (PEC) is more evident in lower Reynolds numbers that can increase the PEC to 75 per cent by creating cross-shape micro-channels. By changing the permeability of micro-channels, PEC will increase by reducing the pressure drop but it has minor changes in Nu.

The current work is applicable to optimizing system performance by decreasing the pressure drop and increasing the heat transfer.

The developed patterns are useful in increasing the system performance including the increase in heat transfer and decrease in pressure drop in systems such as air coolers required in electrical circuits.

Development and optimization of system performance by new patterns using BDPM in comparison to the previous patterns.

This paper aims to identify and examine the internal and external factors that e-business communities in Iran grapple with within value proposition design.

Although the world and global economy have been vastly affected by the financial crisis and the competitive market, most businesses and trade lines are growing significantly by the power of online marketing and e-trades. However, this process is somehow different in the Iranian market. Using literature review and combining it with the casual-comparative method, this study first reviews the literature on the business model and value proposition design and then shows the main challenges Iranian entrepreneurs face in starting their e-business, especially at the time of severe economic, political sanction.

This paper attests to two categories of external and internal obstacles to entrepreneurs in the country. Some internal challenges point to obstacles and problems such as poor infrastructure in technology and network equipment, the security of personal data exchanges, improper infrastructure, including the speed of the internet and its bandwidth limit and lack of programming expertise. In the case of external barriers, this paper addresses the economic sanctions and restrictions that have been imposed on internet businesses.

In this study, the authors intend to identify the challenges of internet businesses in Iran and provide effective solutions for creating new value propositions resulting in rapid and sustainable economic growth.

The aim is to study the conjugate problem of developing laminar mixed convection flow and heat transfer of water‐Al₂O₃ nanofluid inside an inclined tube submitted to a uniform wall heat flux.

The set of non‐linear, coupled and fully elliptic governing equations has been solved using a “finite‐control‐volume” numerical method, the classical power‐law scheme for computing heat and momentum fluxes staggered and non uniform grids for spatial discretization of various regions of the tube.

Numerical results have shown that the presence of nanoparticles slightly intensifies the secondary flow due to buoyancy, in particular in the developing region. It also increases the average Nusselt number and decreases slightly the product ReC_f with respect to those of water. For the horizontal inclination, two new correlations have been proposed to calculate these two variables in the fully developed region, for Grashof number ranging from 10³ to 10⁵ and particle volume concentrations up to 7 per cent.

The results of this study can be employed for various practical heat transfer and thermal applications using nanofluids.

The present study constitutes an original contribution to the knowledge of nanofluid thermal behaviour.