Mohammad Yousefi, Saeed Dinarvand, Mohammad Eftekhari Yazdi and Ioan Pop
The purpose of this paper is to investigate analytically the steady general three-dimensional stagnation-point flow of an aqueous titania-copper hybrid nanofluid past a circular…
Abstract
Purpose
The purpose of this paper is to investigate analytically the steady general three-dimensional stagnation-point flow of an aqueous titania-copper hybrid nanofluid past a circular cylinder that has a sinusoidal radius variation.
Design/methodology/approach
First, the analytic modeling of hybrid nanofluid is presented, and using appropriate similarity variables, the governing equations are transformed into nonlinear ordinary differential equations in the dimensionless stream function, which is solved by the well-known function bvp4c from MATLAB.
Findings
The current solution demonstrates good agreement with those of the previously published studies in the special cases of regular fluid and nanofluids. Graphical results are presented to investigate the influences of the titania and copper nanoparticle volume fractions and also the nodal/saddle indicative parameter on flow and heat transfer characteristics. Here, the thermal characteristics of hybrid nanofluid are found to be higher in comparison to the base fluid and fluid containing single nanoparticles. An important point to note is that the developed model can be used with great confidence to study the flow and heat transfer of hybrid nanofluids.
Originality/value
Analytic modeling of hybrid nanofluid is the important originality of present study. Hybrid nanofluids are potential fluids that offer better heat transfer performance and thermophysical properties than convectional heat transfer fluids (oil, water and ethylene glycol) and nanofluids with single nanoparticles. In this investigation, titania (TiO2, 50 nm), copper (Cu, 20 nm) and the hybrid of these two are separately dispersed into the water as the base fluid and analyzed.
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Faraz Hoseininejad, Saeed Dinarvand and Mohammad Eftekhari Yazdi
This study aims to investigate numerically the problem of conjugate conduction and mixed convection heat transfer of a nanofluid in a rotational/stationary circular enclosure…
Abstract
Purpose
This study aims to investigate numerically the problem of conjugate conduction and mixed convection heat transfer of a nanofluid in a rotational/stationary circular enclosure using a two-phase mixture model.
Design/methodology/approach
Hot and cold surfaces on the wall or inside the enclosure (heater and cooler) are maintained at constant temperature of Th and Tc, respectively, whereas other parts are thermally insulated. To examine the effects of various parameters such as Richardson number (0.01 = Ri =100), thermal conductivity ratio of solid to base fluid (1 = Kr = 100), volume fraction of nanoparticle (0 = φ = 0.05), insertion of conductive covers (C.Cs) around the heater in a different shape (triangular, circular or square), segmentation and arrangement of the conductive blocks (C.Bs) and rotation direction of the enclosure on the flow structure and heat transfer rate, two-dimensional equations of mass, momentum and energy conservation, as well as volume fraction, are solved using finite volume method and Semi-Implicit Method for Pressure Linked Equations (SIMPLE) algorithm.
Findings
The results show that inserting C.C around heater can increase or decrease heat transfer rate, and it depends on thermal conductivity ratio of solid to pure fluid. Also, it is found that by the division of C.B and location of its portions in a horizontal configuration, heat transfer rate reduces. Moreover, it is observed that external heating and cooling of the enclosure causes enhancement of heat transfer relative to that of internal heating and cooling. Finally, results illustrate that under the condition that cylinders rotate in the same direction, the heat transfer rate increases as compared to those that rotate in the opposite direction. Hence rotation direction of cylinders can be used as a desired parameter for controlling heat transfer rate.
Originality/value
A comprehensive report of results for the problem of conjugate conduction and mixed convection heat transfer in a circular cylinder containing different shapes of C.C, conducting obstacle and heater and cooler has been presented. An efficient numerical technique has been developed to solve this problem. The achievements of this paper are purely original, and the numerical results were never published by any researcher.
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Fatemeh Pazooki and Fahimeh Saboori
One of the largest floods in Iran happened in Nowruz in 2019, during which torrents of rain, flooding of rivers, landslides and the destruction of dams caused floods and led to…
Abstract
Purpose
One of the largest floods in Iran happened in Nowruz in 2019, during which torrents of rain, flooding of rivers, landslides and the destruction of dams caused floods and led to financial losses and loss of life in 25 provinces of Iran. During and after the flood, 39 public libraries were closed, three libraries were evacuated and one was completely destroyed.
Design/methodology/approach
Despite the damage that occurred in the libraries, the preventive measures had been taken by many of them to reduce the whole damage. In addition, after the flood, responsible organizations including Iran Public Libraries Institution, the Institute for the Intellectual Development of Children and Young Adults and the Cultural and Art Organization of Municipality and the Mosques and Cultural Center, as well as other relief and social teams, and even people performed activities to reduce the negative impacts caused by the flood.
Findings
This article reviews these activities and their effectiveness. In the end, “the development of a plan for public libraries in natural and social crises” is proposed and the reasons for its necessity are discussed.
Originality/value
This article reviews these activities and their effectiveness. In the end, “the development of a plan for public libraries in natural and social crises” is proposed and the reasons for its necessity are discussed.
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Ioan Pop, Mohammadreza Nademi Rostami and Saeed Dinarvand
The purpose of this article is to study the steady laminar magnetohydrodynamics mixed convection stagnation-point flow of an alumina-graphene/water hybrid nanofluid with spherical…
Abstract
Purpose
The purpose of this article is to study the steady laminar magnetohydrodynamics mixed convection stagnation-point flow of an alumina-graphene/water hybrid nanofluid with spherical nanoparticles over a vertical permeable plate with focus on dual similarity solutions.
Design/methodology/approach
The single-phase hybrid nanofluid modeling is based on nanoparticles and base fluid masses instead of volume fraction of first and second nanoparticles as inputs. After substituting pertinent similarity variables into the basic partial differential equations governing on the problem, the authors obtain a complicated system of nondimensional ordinary differential equations, which has non-unique solution in a certain range of the buoyancy parameter. It is worth mentioning that, the stability analysis of the solutions is also presented and it is shown that always the first solutions are stable and physically realizable.
Findings
It is proved that the magnetic parameter and the wall permeability parameter widen the range of the buoyancy parameter for which the solution exists; however, the opposite trend is valid for second nanoparticle mass. Besides, mass suction at the surface of the plate as well as magnetic parameter leads to reduce both hydrodynamic and thermal boundary layer thicknesses. Moreover, the assisting flow regime always has higher values of similarity skin friction and Nusselt number relative to opposing flow regime.
Originality/value
A novel mass-based model of the hybridity in nanofluids has been used to study the foregoing problem with focus on dual similarity solutions. The results of this paper are completely original and, to the best of the authors’ knowledge, the numerical results of the present paper were never published by any researcher.
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Saeed Dinarvand, Seyed Mehdi Mousavi, Mohammad Yousefi and Mohammadreza Nademi Rostami
The purpose of this paper is to study the steady laminar magnetohydrodynamics (MHD) flow of a magnesium oxide-silver/water hybrid nanofluid along a horizontal slim needle with…
Abstract
Purpose
The purpose of this paper is to study the steady laminar magnetohydrodynamics (MHD) flow of a magnesium oxide-silver/water hybrid nanofluid along a horizontal slim needle with thermal radiation by considering dual solutions.
Design/methodology/approach
It is assumed that the needle can move in the same or opposite direction of the free stream. Also the solid phase and fluid phase are in thermal equilibrium. The basic partial differential equations become dimensionless using a similarity transformation method. Moreover, problem coding is accomplished using the finite difference method. The emerging parameters are nanoparticles mass (0–40 gr), base fluid mass (100 gr), needle’s size (0.001–0.2), magnetic field parameter, velocity ratio parameter, radiation parameter and Prandtl number (6.2).
Findings
With help of the stability analysis, it is shown that always the first solutions are physically stable. Results indicate that the magnetic parameter and the second nanoparticle’s mass limit the range of the velocity ratio parameter for which the solution exists. Besides, the magnetic parameter leads to decrease of quantities of engineering interest, i.e. skin friction coefficient and local Nusselt number.
Originality/value
To the best of the authors’ knowledge, no one has ever attempted to study the present problem through a mass-based model for hybrid nanofluid. Moreover, the dual solutions for the problem are new. Indeed, the results of this paper are purely original and the numerical achievements were never published up to now. Finally, the authors expect that the present investigation would be useful in hot-wire anemometer or shielded thermocouple for measuring the velocity of the wind, etc.
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Saeed Dinarvand, Mohammadreza Nademi Rostami, Rassoul Dinarvand and Ioan Pop
This paper aims to simulate the steady laminar mixed convection incompressible viscous and electrically conducting hybrid nanofluid (CuO-Cu/blood) flow near the plane…
Abstract
Purpose
This paper aims to simulate the steady laminar mixed convection incompressible viscous and electrically conducting hybrid nanofluid (CuO-Cu/blood) flow near the plane stagnation-point over a horizontal porous stretching sheet along with an external magnetic field and induced magnetic field effects that can be applicable in the biomedical fields like the flow dynamics of the micro-circulatory system and especially in drug delivery.
Design/methodology/approach
The basic partial differential equations (PDEs) are altered to a set of dimensionless ordinary differential equations (ODEs) with the help of suitable similarity variables which are then solved numerically using bvp4c scheme from MATLAB. Inasmuch as validation results have shown a good agreement with previous reports, the present novel mass-based algorithm can be used in this problem with great confidence. Governing parameters are both nanoparticle masses, base fluid mass, empirical shape factor of both nanoparticles, suction/injection parameter, magnetic parameter, reciprocal magnetic Prandtl number, Prandtl number, heat source parameter, mixed convection parameter, permeability parameter and frequency ratio. The effect of these parameters on the flow and heat transfer characteristics of the problem is discussed in detail.
Findings
It is shown that the use of CuO and Cu hybrid nanoparticles can reduce the hemodynamics effect of the capillary relative to pure blood case. Moreover, as the imposed magnetic field enhances, the velocity of the blood decreases. Besides, when the blade shapes for both nanoparticles are taken into account, the local heat transfer rate is maximum that is also compatible with experimental observations.
Originality/value
An innovative mass-based model of CuO-Cu/blood hybrid nanofluid has been applied. The novel attitude to one-phase hybrid nanofluid model corresponds to considering nanoparticles mass as well as base fluid mass to computing the solid equivalent volume fraction, the solid equivalent density and also solid equivalent specific heat.