scholarly journals Rotating cylinder and magnetic field on solid particles diffusion inside a porous cavity filled with a nanofluid

2021 ◽  
Vol 11 ◽  
pp. 184798042110342
Author(s):  
Abdelraheem M. Aly ◽  
Ehab Mahmoud Mohamed ◽  
Hakan F. Oztop ◽  
Noura Alsedais
Keyword(s):  
Magnetic Field ◽  
Porous Media ◽  
Rayleigh Number ◽  
Circular Cylinder ◽  
Solid Phase ◽  
Rotational Frequency ◽  
Solid Particles ◽  
Flow Mode ◽  
Porous Layers ◽  
Darcy Parameter

This study deals with the roles of a magnetic field and circular rotation of a circular cylinder on the dissemination of solid phase within a nanofluid-filled square cavity. Two wavy layers of the non-Darcy porous media are situated on the vertical sides of a cavity. An incompressible smoothed particle hydrodynamics (ISPH) method was endorsed to carry out the blending process concerning solid phase into nanofluid and porous media layers. Initially, the solid phase is stationed in a circular cylinder containing two open gates. Implications of a buoyancy ratio ( N = −2: 2), Hartmann number ( Ha = 0: 100), rotational frequency [Formula: see text], Darcy parameter [Formula: see text], Rayleigh number [Formula: see text], nanoparticles parameter [Formula: see text], and amplitude of wavy porous layers [Formula: see text] on the lineaments of heat/mass transport have been carried out. The results revealed that the diffusion of the solid phase is permanently moving toward upward except at opposing flow mode [Formula: see text] toward downward. The lower Rayleigh number reduces the solid-phase diffusions. A reduction in a Darcy parameter lessens the nanofluid speed and solid-phase diffusions in the porous layers. A reduction in [Formula: see text] from [Formula: see text] to [Formula: see text] diminishes the maximum of streamlines [Formula: see text] by 13.19% at [Formula: see text], by 46.75% at [Formula: see text], and by 74.75% at [Formula: see text].

scholarly journals NATURAL CONVECTIVE HEAT TRANSFER IN A POROUS MEDIUM WITHIN A TWO DIMENSIONAL ENCLOSURE

2017 ◽  
Vol 18 (2) ◽  
pp. 196-211 ◽  
Author(s):  
Mehdi Ahmadi
Keyword(s):  
Heat Transfer ◽  
Porous Media ◽  
Nusselt Number ◽  
Natural Convection ◽  
Rayleigh Number ◽  
Solid Phase ◽  
Fluid Motion ◽  
Darcy Number ◽  
Large Share ◽  
Porous Media Model

In this paper, to achievement the effect of increase number of heating components arrangement on the rate of heat transfer of natural convection, that others have been less noticed. Therefore, in each stage increase the number of heating components so much the space occupied by them remains constant. Then by calculating the amount of heat transfer in different Rayleigh number became clear that minify and distributing heating solid phase in the enclosure increases the total Nusselt number and heat transfer, One reason could be high intensity of fluid motion in corners and near walls of the enclosure. In the next section with the solid phases on the enclosure can be made porous media model. As the results showed an increase in average Rayleigh number, Nusselt number has increased. Also be seen in the lower Darcy numbers, speed of increase in Nusselt number with increase in average Rayleigh number is higher. It can be said that in enclosure by any number of solid pieces with certain Darcy number, with an increase in average Rayleigh number, circular flow inside the enclosure becomes more intense and isothermal lines near walls with constant temperature are so dense, that represents an increase in rate of heat transfer. Also by increasing the Darcy number, rate of heat transfer from the porous media has decreased, as regards that a large share of heat transfer in porous media is done by conduction, although increasing Darcy number increases heat transfer of natural convection but decrease a heat transfer of conduction, therefore decrease total of heat transfer.

Natural Convection in Horizontal Porous Layers: Effects of Darcy and Prandtl Numbers

1989 ◽  
Vol 111 (4) ◽  
pp. 926-935 ◽  
Author(s):  
N. Kladias ◽  
V. Prasad
Keyword(s):  
Porous Medium ◽  
Natural Convection ◽  
Rayleigh Number ◽  
Prandtl Number ◽  
Numerical Solutions ◽  
Fluid Layer ◽  
Darcy Number ◽  
Solid Particles ◽  
Convection Regime ◽  
Porous Layers

Natural convection in horizontal porous layers heated from below is studied by employing a formulation based on the Brinkman–Forchheimer–extended Darcy equation of motion. The numerical solutions show that the convective flow is initiated at lower fluid Rayleigh number Raf than that predicted by the linear stability analysis for the Darcy flow model. The effect is considerable, particularly at a Darcy number Da greater than 10−4. On the other hand, an increase in the thermal conductivity of solid particles has a stabilizing effect. Also, the Rayleigh number Raf required for the onset of convection increases as the fluid Prandtl number is decreased. In the stable convection regime, the heat transfer rate increases with the Rayleigh number, the Prandtl number, the Darcy number, and the ratio of the solid and fluid thermal conductivities. However, there exists an asymptotic convection regime where the porous media solutions are independent of the permeability of the porous matrix or Darcy number. In this regime, the temperature and flow fields are very similar to those obtained for a fluid layer heated from below. Indeed, the Nusselt numbers for a porous medium with kf = ks match with the fluid results. The effect of Prandtl number is observed to be significant for Prf < 10, and is strengthened with an increase in Raf, Da, and ks/kf. An interesting effect, that a porous medium can transport more energy than the saturating fluid alone, is also revealed.

Effects of a magnetic field on double-diffusive convection of a nanofluid in a cavity saturated by wavy layers of porous media: ISPH analysis

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Abdelraheem M. Aly ◽  
Noura Alsedais ◽  
Hakan F. Oztop
Keyword(s):  
Magnetic Field ◽  
Circular Cylinder ◽  
Hartmann Number ◽  
Maximum Flow ◽  
Flow Speed ◽  
Content Type ◽  
Porous Layers ◽  
Amplitude Parameter ◽  
Diffusive Convection ◽  
Double Diffusive

Purpose The purpose of this study is to use the incompressible smoothed particle hydrodynamics method to examine the influences of a magnetic field on the double-diffusive convection caused by a rotating circular cylinder with paddles within a square cavity filled by a nanofluid. Design/methodology/approach The cavity is saturated by two wavy layers of non-Darcy porous media with a variable amplitude parameter. The embedded circular cylinder with paddles carrying T_h and C_h is rotating around the cavity center by a uniform circular velocity. Findings The lineaments of nanofluid velocity and convective flow, as well as the mean of Nusselt and Sherwood numbers, are represented below the variations on the frequency parameter, amplitude parameter of the wavy porous layers, Darcy parameter, nanoparticles parameter, Hartmann number and Ryleigh number. The performed simulations showed the role of paddles mounted on circular cylinders for enhancing the transmission of heat and mass within a cavity. The wavy porous layers at the lower Darcy parameter are playing as a blockage for the nanofluid flow within the porous area. Increasing the concentration of the nanoparticles to 6% reduces the maximum flow speed by 8.97% and maximum streamlines |ψ|max by 10.76%. Increasing Hartmann number to 100 reduces the maximum flow speed by 65.83% and |ψ|max by 75.54%. Originality/value The novelty of this work is to examine the effects of an inclined magnetic field and rotating novel shape of a circular cylinder with paddles on the transmission of heat/mass in the interior of a nanofluid-filled cavity saturated by undulating porous medium layers.

Thermosolutal convection of a nanofluid in ∧-shaped cavity saturated by a porous medium

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Abdelraheem M. Aly ◽  
Zehba Raizah
Keyword(s):  
Porous Medium ◽  
Porous Media ◽  
Circular Cylinder ◽  
Volume Fraction ◽  
Heterogeneous Porous Media ◽  
Thermosolutal Convection ◽  
Content Type ◽  
Solutal Convection ◽  
Buoyancy Ratio ◽  
Darcy Parameter

Purpose The purpose of this study is to simulate the thermo-solutal convection resulting from a circular cylinder hanging in a rod inside a ∧-shaped cavity. Design/methodology/approach The two dimensional ∧-shaped cavity is filled by Al2O3-water nanofluid and saturated by three different levels of heterogeneous porous media. An incompressible smoothed particle hydrodynamics (ISPH) method is adopted to solve the governing equations of the present problem. The present simulations have been performed for the alteration of buoyancy ratio (−2≤N≤2), radius of a circular cylinder (0.05≤Rc≤0.3), a height of a rod (0.1≤Lh≤0.4), Darcy parameter (10−3≤Da≤10−5), Lewis number (1≤Le≤40), solid volume fraction (0≤ϕ≤0.06), porous levels (0≤η1=η2≤1.5)and various boundary-wall conditions. Findings The performed numerical simulations indicated the importance of embedded shapes on the distributions of temperature, concentration and velocity fields inside ∧-shaped cavity. Increasing buoyancy ratio parameter enhances thermo-solutal convection and nanofluid velocity. Adiabatic conditions of the vertical-walls of ∧-shaped cavity augment the distributions of the temperature and concentration. Regardless the Darcy parameter, a homogeneous porous medium gives the lowest values of a nanofluid velocity. Originality/value ISPH method is used to simulate thermo-solutal convection of a nanofluid inside a novel ∧-shaped cavity containing a novel embedded shape and heterogeneous porous media.

Comparative Study on Compositions of Oil-Water Transition Layer before and after ClO2-Treatment Process

2013 ◽  
Vol 652-654 ◽  
pp. 749-752
Author(s):  
Dan Dan Yuan ◽  
Hong Jun Wu ◽  
Hai Xia Sheng ◽  
Xin Sui ◽  
Bao Hui Wang
Keyword(s):  
Chemical Composition ◽  
Transition Layer ◽  
Solid Phase ◽  
Settling Tank ◽  
Physical Structure ◽  
Solid Particles ◽  
Viscosity Reduction ◽  
Insoluble Residue ◽  
Before And After ◽  
Oil Water

In order to meet the need of separating oil from water in the settling tank of the oilfield, ClO2 treatment for oil-water transition layer in settling tank is introduced. The field test displayed that the technique was achieved by a good performance. For understanding the oxidation and mechanism, compositions of oil-water transition layer were comparatively studied for before/after ClO2-treatment in this paper.The experimental results show that the compositions before and after ClO2-treatment, including physical structure and chemical composition, were varied in the great extension. The physical structure, consisting of water, oil and solid phase, was reduced to less than 5% of water and 0.5% of solid particle and increased to 95% of oil in layer compared with before-treatment, easily leading to clearly separating water from oil. The chemical composition of iron sulfide and acid insoluble substance in solid phase was decreased to more than 90% while the carbonate was reduced more than 70% . After the treatment, the viscosity reduction of the water phase in the layer was reached to 50% after oxidation demulsification with ClO2. The chemistry was discussed based on the principles and experiments. Due to ClO2 destroying (oxidizing) the rigid interface membrane structure which is supported by natural surfactant, polymer and solid particles with interface-active materials, the action accelerates the separating of water and oil and sedimentation of insoluble residue of acid in the layer. By demonstrating the experimental data and discussion, we can effectively control the oxidation performance of chlorine dioxide, which is very meaningful for oilfield on the aspect of stable production of petroleum.

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