scholarly journals Study on filtration performance of elliptical fiber with different arrangements

2020 ◽  
Vol 15 ◽  
pp. 155892501989388
Author(s):  
JiaWei Zhou ◽  
Liang Zhang ◽  
Bo Zhang ◽  
Wei Gong
Keyword(s):  
Quality Factor ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Particle Diameter ◽  
Dense Layer ◽  
Fibrous Media ◽  
Bimodal Structure ◽  
Filtration Performance ◽  
Particle Penetration ◽  
Circular Fiber

The fibrous media composed of elliptical fibers is widely used owing to the high filtration efficiency. However, there are few studies on the arrangement of non-circular fibers, although the single non-circular fiber has been clearly investigated. In this article, two-dimensional numerical geometries of fibrous media with different elliptical fiber arrangements, namely, random distribution structure, dense–sparse structure, and bimodal structure, are developed for studying filtration performance. The results show that the large aspect ratio and solid volume fraction represent low particle penetration. When the particle diameter ( Dp) is small, the quality factor of bimodal structure is higher than the dense–sparse structure, especially at Dp = 50 nm. For the large Dp, the opposite is true. Meanwhile, reducing fiber diameter ( Df) is more significant than increasing solid volume fraction in terms of improving penetration. As for dense–sparse structure, replacing the elliptical fibers in sparse layers with circular fibers can comprehensively improve the quality factor of fibrous media. However, if the replacement between elliptical fiber and circular fiber occurs in dense layer, it will result in high quality factor at Dp ⩽ 500 nm, while low quality factor at Dp > 500 nm.

An Efficient Immersed Boundary Method Based on Penalized Direct Forcing for Simulating Flows Through Real Porous Media

2012 ◽  
Author(s):  
Wim-Paul Breugem ◽  
Vincent van Dijk ◽  
René Delfos
Keyword(s):  
Porous Medium ◽  
Ct Scan ◽  
Immersed Boundary Method ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Particle Diameter ◽  
Immersed Boundary ◽  
Average Particle ◽  
Boundary Method ◽  
Direct Forcing

A computationally efficient Immersed Boundary Method (IBM) based on penalized direct forcing was employed to determine the permeability of a real porous medium. The porous medium was composed of about 9000 glass beads with an average particle diameter of 1.93 mm and a porosity of 0.367. The forcing of the IBM depends on the local solid volume fraction within a computational grid cell. The latter could be obtained from a high-resolution X-ray Computed Tomography (CT) scan of the packing. An experimental facility was built to determine the permeability of the packing experimentally. Numerical simulations were performed for the same packing based on the data from the CT scan. For a scan resolution of 0.1 mm the numerical value for the permeability was nearly 70% larger than the experimental value. An error analysis indicated that the scan resolution of 0.1 mm was too coarse for this packing.

scholarly journals Numerical investigation of solid-liquid slurry flow through an upward-facing step

2013 ◽  
Vol 61 (2) ◽  
pp. 126-133g ◽  
Author(s):  
Gianandrea Vittorio Messa ◽  
Stefano Malavasi
Keyword(s):  
Experimental Data ◽  
Volume Fraction ◽  
Particle Density ◽  
Solid Volume Fraction ◽  
Particle Diameter ◽  
Expansion Ratio ◽  
Water Mixture ◽  
Horizontal Pipe ◽  
Liquid Slurry ◽  
Solid Liquid

Abstract The flow of a solid-water mixture through an upward-facing step in a channel is numerically investigated. The effect of expansion ratio, mean solids volume fraction and particle diameter on the velocity field, pressure distribution and solid volume fraction field is studied. Expansion ratios of 0.50 and 0.67, particle diameter of 125 μm and 440 μm and mean solid volume fraction between 0.05 and 0.20 are considered. Particle density is 2465 kg m-3. An Eulerian twofluid model is used to simulate the flow. Due to the lack of experimental data, the model was validated by comparison to other numerical investigations and to experimental data about the horizontal pipe case. Afterwards, it is studied the effect of the above mentioned parameters upon the degree of coupling between the phases and the extension of the disturbance region in the pressure and solid volume fraction fields downstream the step. Parameters of engineering interest, such as the reattachment length and the pressure recovery downstream the enlargement, are investigated.

scholarly journals Numerical simulation and optimization of solid-liquid two-phase flow in a back-swept axial-flow pump

2017 ◽  
Vol 21 (4) ◽  
pp. 1751-1757 ◽  
Author(s):  
De-Sheng Zhang ◽  
Qiang Pan ◽  
Zhang Hu ◽  
Wei-Dong Shi ◽  
Rui-Jie Zhang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Sewage Treatment Plant ◽  
Particle Diameter ◽  
Axial Flow ◽  
Wear Property ◽  
Simulation And Optimization ◽  
Axial Flow Pump ◽  
Flow Pump

The simulation study is proposed to analyze the wear property of the axial flow pump using the sewage as medium. Different axial flow pumps are designed with different back-swept angles, of which are 40?, 65?, and 90?. Numerical simulation results showed the relationship between solid volume fraction and back-swept angle on the pressure/suction surface, as well as the particle diameter. To validate the correctness of numerical investigation, the result of the 65? backswept blade model was compared with a sludge axial flow pump in sewage treatment plant, which showed fair agreement with the simulated results.

Influence of fibre properties and its proportion on filtration behaviour of thermo-bonded multilayer nonwoven

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Gobi Nallathambi
Keyword(s):  
Particle Size ◽  
Pressure Drop ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Filtration Efficiency ◽  
Human Beings ◽  
Fibre Properties ◽  
Content Type ◽  
Filtration Performance ◽  
Different Diameters

Purpose The purpose of this paper is to study the influence of fibre properties on filtration behavior. Air pollution is a major threat to human beings due to industrialization and urbanization. Among various particles in the atmospheric air, PM 2.5 causes various respiratory problems to human beings and also causes premature engine wear. The primary importance for the filters is higher filtration efficiency with lower pressure drop. Design/methodology/approach In this research, nonwoven filters were developed with different diameters of polyester fibres such as 0.8d, 1.2d and 6d fibres and different proportions of fibres were used. The Kuwabara cell model was used to derive certain parameters and its effects were analysed. The effect of basis length, solid volume fraction and porosity on filtration behavior was discussed in detail. Findings The filtration efficiency is higher for particle size from 1–3 µm, when different layers of polyester fibres are used with coarser fibres as the top layer and finer as the bottom layer. The filtration performance is better for layered nonwoven than unimodal nonwoven. The higher proportion of micro-denier fibres results in higher filtration efficiency with higher pressure drop. Research limitations/implications The proposed research is more suitable for the particle size of more than 1 µm because of the fibre diameters and its achievable porosity. The filtration efficiency can be increased further by increasing the mass per unit area, which also increases the pressure and is not recommended. Originality/value The effect of triple-layers with different diameters of fibres on filtration was analysed. Due to the variation in diameters of fibres in different layers, the filtration performance varies.

scholarly journals Comprehensive Optimization of the Dispersion of Mixing Particles in an Inert-Particle Spouted-Bed Reactor (IPSBR) System

Processes ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 1921
Author(s):  
Ameera F. Mohammad ◽  
Aya A-H. I. Mourad ◽  
Ali H. Al-Marzouqi ◽  
Muftah H. El-Naas ◽  
Bart Van der Bruggen ◽  
...  
Keyword(s):  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Particle Diameter ◽  
Operating Conditions ◽  
Solid Particles ◽  
Orifice Diameter ◽  
Inert Particle ◽  
Gas Velocity ◽  
Spouted Bed ◽  
Gas Dispersion

Effective gas dispersion and liquid mixing are significant parameters in the design of an inert-particle spouted-bed reactor (IPSBR) system. Solid particles can be used to ensure good mixing and an efficient rate of mass and heat transfer between the gas and liquid. In this study, computational fluid dynamics (CFD) coupled with the discrete phase model (DPM) were developed to investigate the effect of the feed gas velocity (0.5–1.5 m/s), orifice diameter (0.001–0.005 m), gas head (0.15–0.35 m), particle diameter (0.009–0.0225 m), and mixing-particle-to-reactor-volume fraction (2.0–10.0 vol.%) on the solid mass concentration, average solid velocity, and average solid volume fraction in the upper, middle, and conical regions of the reactor. Statistical analysis was performed using a second-order response surface methodology (RSM) with central composite design (CCD) to obtain the optimal operating conditions. Selected parameters were optimized to maximize the responses in the middle and upper regions, and minimize them in the conical region. Such conditions produced a high interfacial area and fewer dead zones owing to good particle dispersion. The optimal process variables were feed gas velocity of 1.5 m/s, orifice diameter of 0.001 m, gas head of 0.2025 m, a particle diameter of 0.01 m, and a particle load of 0.02 kg. The minimum average air velocity and maximum air volume fraction were observed under the same operating conditions. This confirmed the novelty of the reactor, which could work at a high feed gas velocity while maintaining a high residence time and gas volume fraction.

scholarly journals Dense granular flow rheology in turbulent bedload transport

2016 ◽  
Vol 804 ◽  
pp. 490-512 ◽  
Author(s):  
Raphael Maurin ◽  
Julien Chauchat ◽  
Philippe Frey
Keyword(s):  
Granular Flow ◽  
Large Scale ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Particle Diameter ◽  
Bedload Transport ◽  
Spherical Particles ◽  
Granular Rheology ◽  
Wide Range ◽  
Dense Granular Flow

The local granular rheology is investigated numerically in turbulent bedload transport. Considering spherical particles, steady uniform configurations are simulated using a coupled fluid–discrete-element model. The stress tensor is computed as a function of the depth for a series of simulations varying the Shields number, the specific density and the particle diameter. The results are analysed in the framework of the $\unicode[STIX]{x1D707}(I)$ rheology and exhibit a collapse of both the shear to normal stress ratio and the solid volume fraction over a wide range of inertial numbers. Contrary to expectations, the effect of the interstitial fluid on the granular rheology is shown to be negligible, supporting recent work suggesting the absence of a clear transition between the free-fall and turbulent regimes. In addition, data collapse is observed up to unexpectedly high inertial numbers $I\sim 2$, challenging the existing conceptions and parametrisation of the $\unicode[STIX]{x1D707}(I)$ rheology. Focusing upon bedload transport modelling, the results are pragmatically analysed in the $\unicode[STIX]{x1D707}(I)$ framework in order to propose a granular rheology for bedload transport. The proposed rheology is tested using a 1D volume-averaged two-phase continuous model, and is shown to accurately reproduce the dense granular flow profiles and the sediment transport rate over a wide range of Shields numbers. The present contribution represents a step in the upscaling process from particle-scale simulations towards large-scale applications involving complex flow geometry.

Ciliary Flow of Casson Nanofluid with the Influence of MHD having Carbon Nanotubes

2020 ◽  
Vol 16 ◽  
Author(s):  
Adel Alblawi ◽  
Saba Keyani ◽  
S. Nadeem ◽  
Alibek Issakhov ◽  
Ibrahim M. Alarifi
Keyword(s):  
Carbon Nanotubes ◽  
Velocity Profile ◽  
Pressure Gradient ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Pressure Rise ◽  
Shear Stresses ◽  
Left Wall ◽  
Coupled Equations ◽  
The Right

Objective: In this paper, we consider a model that describes the ciliary beating in the form of metachronal waves along with the effects of Magnetohydrodynamic fluid over a curved channel with slip effects. This work aims at evaluating the effect of Magnetohydrodynamic (MHD) on the steady two dimensional (2-D) mixed convection flow induced in carbon nanotubes. The work is done for both the single wall nanotube and multiple wall nanotube. The right wall and the left wall possess a metachronal wave that is travelling along the outer boundary of the channel. Methods: The wavelength is considered as very large for cilia induced MHD flow. The governing linear coupled equations are simplified by considering the approximations of long wavelength and small Reynolds number. Exact solutions are obtained for temperature and velocity profile. The analytical expressions for the pressure gradient and wall shear stresses are obtained. Term for pressure rise is obtained by applying Numerical integration method. Results: Numerical results of velocity profile are mentioned in a table form, for various values of solid volume fraction, curvature, Hartmann number [M] and Casson fluid parameter [ζ]. Final section of this paper is devoted to discussing the graphical results of temperature, pressure gradient, pressure rise, shear stresses and stream functions. Conclusion: Velocity profile near the right wall of the channel decreases when we add nanoparticles into our base fluid, whereas an opposite behaviour is depicted near the left wall due to ciliated tips whereas the temperature is an increasing function of B and ߛ and decreasing function of ߶.

scholarly journals Quantification of shear viscosity and wall slip velocity of highly concentrated suspensions with non-Newtonian matrices in pressure driven flows

2021 ◽  
Author(s):  
Patrick Wilms ◽  
Jan Wieringa ◽  
Theo Blijdenstein ◽  
Kees van Malssen ◽  
Reinhard Kohlus
Keyword(s):  
Shear Stress ◽  
Liquid Phase ◽  
Shear Rate ◽  
Shear Viscosity ◽  
Slip Velocity ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Wall Slip ◽  
Flow Index ◽  
Concentrated Suspensions

AbstractThe rheological characterization of concentrated suspensions is complicated by the heterogeneous nature of their flow. In this contribution, the shear viscosity and wall slip velocity are quantified for highly concentrated suspensions (solid volume fractions of 0.55–0.60, D4,3 ~ 5 µm). The shear viscosity was determined using a high-pressure capillary rheometer equipped with a 3D-printed die that has a grooved surface of the internal flow channel. The wall slip velocity was then calculated from the difference between the apparent shear rates through a rough and smooth die, at identical wall shear stress. The influence of liquid phase rheology on the wall slip velocity was investigated by using different thickeners, resulting in different degrees of shear rate dependency, i.e. the flow indices varied between 0.20 and 1.00. The wall slip velocity scaled with the flow index of the liquid phase at a solid volume fraction of 0.60 and showed increasingly large deviations with decreasing solid volume fraction. It is hypothesized that these deviations are related to shear-induced migration of solids and macromolecules due to the large shear stress and shear rate gradients.

Effects of uniform or non-uniform heating at bottom wall on MHD mixed convection in a porous cavity saturated by nanofluid

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Subramanian Muthukumar ◽  
Selvaraj Sureshkumar ◽  
Arthanari Malleswaran ◽  
Murugan Muthtamilselvan ◽  
Eswari Prem
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Transfer Rate ◽  
Hartmann Number ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Darcy Number ◽  
Bottom Wall ◽  
Uniform Heating ◽  
The Magnetic Field

Abstract A numerical investigation on the effects of uniform and non-uniform heating of bottom wall on mixed convective heat transfer in a square porous chamber filled with nanofluid in the appearance of magnetic field is carried out. Uniform or sinusoidal heat source is fixed at the bottom wall. The top wall moves in either positive or negative direction with a constant cold temperature. The vertical sidewalls are thermally insulated. The finite volume approach based on SIMPLE algorithm is followed for solving the governing equations. The different parameters connected with this study are Richardson number (0.01 ≤ Ri ≤ 100), Darcy number (10−4 ≤ Da ≤ 10−1), Hartmann number (0 ≤ Ha ≤ 70), and the solid volume fraction (0.00 ≤ χ ≤ 0.06). The results are presented graphically in the form of isotherms, streamlines, mid-plane velocities, and Nusselt numbers for the various combinations of the considered parameters. It is observed that the overall heat transfer rate is low at Ri = 100 in the positive direction of lid movement, whereas it is low at Ri = 1 in the negative direction. The average Nusselt number is lowered on growing Hartmann number for all considered moving directions of top wall with non-uniform heating. The low permeability, Da = 10−4 keeps the flow pattern same dominating the magnetic field, whereas magnetic field strongly affects the flow pattern dominating the high Darcy number Da = 10−1. The heat transfer rate increases on enhancing the solid volume fraction regardless of the magnetic field.

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