Fluid Velocity Distribution Research Articles

Heat and mass flux analysis of magneto-free-convection flow of Oldroyd-B fluid through porous layered inclined plate

The present work examines the analytical solutions of the double duffusive magneto free convective flow of Oldroyd-B fluid model of an inclined plate saturated in a porous media, either fixed or moving oscillated with existence of slanted externally magnetic field. The phenomenon has been expressed in terms of partial differential equations, then transformed the governing equations in non-dimensional form. On the fluid velocity, the influence of different angles that plate make with vertical is studied as well as slanted angles of the electro magnetic lines with the porous layered inclined plate are also discussed, associated with thermal conductivity and constant concentration. For seeking exact solutions in terms of special functions namely Mittag–Leffler functions, G-function etc., for Oldroyd-B fluid velocity, concentration and Oldroyd-B fluid temperature, Laplace integral transformation method is used to solve the non-dimensional model. The contribution of different velocity components are considered as thermal, mass and mechanical, and analyse the impacts of these components on the fluid dynamics. For several physical significance of various fluidic parameters on Oldroyd-B fluid velocity, concentration and Oldroyd-B fluid temperature distributions are demonstrated through various graphs. Furthermore, for being validated the acquired solutions, some limiting models such as Newtonian fluid in the absence of different fluidic parameters. Moreover, the graphical representations of the analytical solutions illustrated the main results of the present work and studied various cases regarding the movement of plate.

Numerical study on the effect of airflow on powder mixing in a container blender

Powder mixing is critical in many industries. Despite the wide variety of available mixers, the container blender is favored in industries due to easy manufacturing and convenient operation. As fine powders are frequently encountered in practical mixing, the presence of air during mixing may significantly impact the process. However, a scientific understanding of air–particle interactions in powder mixing has not been established so far. From a physical view, the air drag force on particles might be significant when the gas velocity is high and the particles are fine. Therefore, this novel study numerically investigates the effects of particle size and air presence on powder mixing under typical conditions, such that the relationship between particle–fluid dynamics and mixing performance is clarified for the first time. In the calculation, our advanced computational fluid dynamics–discrete element method, namely, the flexible Eulerian–Lagrangian method with an implicit algorithm, is utilized. To examine the effect of particle size on powder mixing, the coarse-grained discrete element method is employed for fine particle systems. Through the advanced numerical framework, the effect of airflow on powder mixing can be discussed in depth. The numerical results show that airflow accelerates the mixing of fine particles under the investigated rotation speeds. Based on the calculation results of the particle kinetics and fluid velocity distribution, it is clarified that the accelerated mixing results from the fine particle movement under air entrainment. How the movement of fine particles is developed is also elucidated by the continuously circulating gas flow and fluid drag force. Thus, this study provides a new understanding of the effects of airflow on powder mixing, which has not been scientifically clarified in previous studies.

ROLL-BOND HEAT EXCHANGER (RHE) DESIGN AND APPLICATION TO A CHOCOLATE COOLING TUNNEL - A NUMERICAL STUDY

The snack sector has a significant market today. It is expected that the snacks will look as promised on the packaging and that the product will have no deformations or defects. The entire area of liquid chocolate- covered snack products entering the chocolate cooling tunnel must be cooled homogeneously. If all surfaces of the chocolate are not sufficiently cooled, a problem of sticking to the conveyor belt can occur. This study investigates the performance of roll-bond heat exchangers under different operating conditions to solve the snack sector’s technical problems. For this purpose, a CAD model of a roll-bond heat exchanger is created. A steady-state heat transfer problem is established in the SolidWorks Flow Simulation environment, and the problem is solve numerically. The maximum, minimum, and average values of the fluid temperature, pressure difference, fluid velocity, and solid temperature distributions are calculated for different inlet velocities and temperatures. In addition, the standard deviations of the solid temperature values are calculated and evaluated. The results show that the roll-bond heat exchanger applies to the chocolate cooling tunnel and is much more efficient for heat transfer than the conventional design.

A Novel Method for Wet Gas Flow Measurements Based on an Over-Reading Principle

A novel method to measure the flow rate in a wet gas is presented. Due to the presence of liquid, there is a deviation in the measurement of the gas volume flow rate obtained with standard vortex flow-meters. The proposed method is based on a correction factor determined through the application of an over-reading approach to a bluff body in mist flow. The correction factor is obtained from the slip velocity ratio, i.e., the ratio of droplet velocity to gas velocity, based on the analysis of the fluid velocity distribution in the pipeline section. It also takes into account relevant theoretical arguments. It is shown that the predicted results fit the experimental results well.

Numerical investigation of seepage characteristics of propped fracture in coalbed methane reservoirs

The investigation of the pore structure characteristics and the effect on fluid seepage in propped fractures are important considerations for improving coalbed methane (CBM) production and optimizing CBM extraction systems. In this paper, a numerical model was established to study the pore structure characteristics and distribution of fluid pressure, velocity and pathline fields of propped fractures. The results showed that, with the increase of the closure stress, the porosity decreased linearly while the effective pore connectivity ratio first increased, then decreased. The best flow conductivity of the fracture was achieved at the closure stress of 12.67 MPa. In addition, there were disparities in the pore distribution of the different layers due to the uneven transfer of the closure stress from top to bottom. Compared to the top and bottom layers, the effective pore connectivity ratio and fluid pressure were significantly smaller in the middle layer, while the flow velocity and pathline length were larger. The top and bottom layers were the main fluid seepage channels. The results of this study can provide a theoretical basis for CBM production prediction and real-time quantitative optimization of CBM extraction systems.

Relationship between pore fluid velocity distribution and pore size distribution

AbstractThis study investigated the normalized velocity magnitude distribution and normalized pore volume distribution in different porous media with porosity between 13.5% and 85%, including sandstones, carbonates, synthetic silica, sphere packings and fiber scaffolds. It was found that both velocity magnitude and pore size follow the same distribution. These results allow the prediction of the velocity distribution in a porous medium when its pore structure is known or tuning the velocity by controlling the pore structure.

Analysis of Fluid Flow on the N95 Facepiece Filtration Layers

Due to the general confusion over the mask's efficiency against COVID-19 virus droplets, professionals and the public may find it difficult to stop the disease from spreading. This study intends to investigate the fluid flow across the N95 filtration layer based on the experimental data and create a simulation model based on the analysis. Therefore, the fluid flow across the filtration layer is simulated using ANSYS Fluent, part of Computational Fluid Dynamics (CFD) solver software. This study anticipates the fluid flow across the N95 by using the porous media approach, in which inertial resistance and viscous resistance are introduced in the simulation by obtaining the pressure drop coefficient of the actual 3M N95 filtration. The fluid passed through the filtration layer with some velocity range based on the MS 2323:2010 standard. The pressure and velocity distribution of fluid through the filtration layer are analyzed by simulation illustration of the contour and streamline of the fluid. For most conditions, as fluid flowed across the filter, the flow gradually began to retard and diverge around the filtration layer. Besides, different flow rates across the filtration layer also result in different pressure distributions on the N95 layer. To sum up, this study is beneficial in forecasting the fluid behavior across the filtration layer by applying the porous zone approach in the ANSYS simulation.

Electroosmotic slip flow of Eyring fluid under high Zeta potential in a circular microchannel

• Under the combined action of applied electric field force and pressure, the electroosmotic flow of Eyring fluid with Navier slip boundary condition at high Zeta potential. • Apply the Chebyshev spectral method to solve the electric potential distribution, and then apply the numerical method (compound trapezoidal formula) to solve the fluid velocity distribution. • The influences of relevant physical parameters on the velocity are analyzed for the Eyring fluid. In this paper, the electroosmotic flow of Eyring fluid with Navier slip boundary condition under high Zeta potential in a circular micropipe under the combined use of applied electric field force and pressure is studied. The finite difference method is traditionally used to solve the electric potential distribution and fluid velocity distribution under high Zeta potential. In this paper, we try to use the Chebyshev spectral method to solve the electric potential distribution and fluid velocity distribution, and the results are compared with the analytical approximate solution obtained by Debye-Hückel (D-H) linear approximation [1] and the numerical solution obtained by the classical finite difference method. The result not only confirms the validity of the Chebyshev spectral method, but also shows that it has the advantages of high precision and a small amount of calculation; In addition, the effects of various physical parameters on electroosmotic flow are discussed in detail, and it is obtained that the velocity distribution of the Eyring fluid increases with the increase of the electric potential under the high zeta potential.

A novel DEM-based pore-scale thermal-hydro-mechanical model for fractured non-saturated porous materials

For fracture propagation, a novel DEM-based pore-scale thermal-hydro-mechanical model of two-phase fluid flow with heat transfer in non-saturated porous materials with low porosity was developed. Numerical computations were performed for bonded granular specimens, using a DEM fully coupled with CFD (based on a fluid flow network) and heat transfer, which integrated discrete mechanics with fluid mechanics and heat transfer at the meso-scale. Both the fluid (diffusion and advection) and bonded particles (conduction) were involved in heat transfer. The numerical findings of the coupled thermal-hydraulic-mechanical (THM) model were first compared to the analytical solution of the classic 1D heat transport problem. The numerical and analytical outcomes were in perfect agreement. Advection's impacts on the cooling of a bonded particle assembly were next numerically demonstrated for low and high Peclet numbers. Finally, the THM model's utility was proved in a thermal contraction test employing a bonded particle assembly during cooling, which resulted in the creation of a macro-crack. The effects of a macro-crack on the distribution of fluid pressure, density, velocity, and temperature were studied.

Flow Analysis of Brinkman-Viscoelastic Fluid in Boundary Layer Region of Horizontal Circular Cylinder

This paper examines the flow of Brinkman-viscoelastic fluid in the boundary layer region. The flow over a Horizontal Circular Cylinder (HCC) is investigated theoretically. The proposed model’s governing equations, which are partial differential equations (PDEs), are transformed to their simplest form by using the appropriate non-dimensional variables and non-similarity transformation. The numerical computations for the obtained equations are then computed using the Keller-box method (KBM) which is programmed in MATLAB R2019a software. The velocity distribution results, together with the coefficient of skin friction are presented. A comparison study with previously published results is carried out to ensure that the current findings are accurate. It is discovered that the presence of the Brinkman and viscoelastic parameters influences the velocity behaviour of fluid, with a tendency to decrease the velocity distribution of fluid. Furthermore, both parameters have the potential to decrease the skin friction coefficient. The output can be used as a starting point for complex flow problems that occur frequently in engineering applications.

Magnetohydrodynamic chemically reactive viscoelastic fluid flow through an inclined porous layer

AbstractAnalysis of a time‐independent magnetohydrodynamic viscoelastic fluid flow in a deformable inclined porous layer with first‐order chemical reaction has been investigated. Walters' fluid model has been used to study viscoelastic fluid. The walls are suctioned/injected at a constant rate. The expression representing the solution for solid displacement, fluid velocity, temperature, and concentration distribution is obtained. The effect of applicable parameters on solid displacement, fluid velocity, temperature, and concentration are discussed graphically, while skin friction, heat transfer, and mass transfer are revealed in a tabular structure. It is noticed that solid displacement, fluid velocity, and temperature profiles decrease when the viscoelastic parameter increase. Solid displacement enhances and the velocity of the fluid reduces owing to the influence of increasing drag parameter, whereas the reverse effect is seen for the volume fraction parameter. Nusselt number at the walls shows the opposite behavior for the viscoelastic parameter and Eckert number. Sherwood number at the walls shows opposite behavior for Reynolds number, Schmidt number, and radiation parameter. Also, the entropy generation number rises as a result of the influence of viscoelasticity and Eckert number.

A simple portable magnetic resonance technique for characterizing circular couette flow of non-Newtonian fluids

In this work, we expand on past portable magnetic resonance flow methods and propose a novel method for characterizing circular (laminar) Couette flow of non-Newtonian fluids. Symmetry of the flow system combined with a constant magnetic field gradient leads to phase interference, affecting the signal magnitude, and net phase cancellation when averaging across the excited slice, preventing the use of phase-sensitive methods. Therefore, we utilize the dependence of signal magnitude at variable echo times and shear rates to characterize rheological properties. Theoretical equations governing the velocity distributions of fluids that obey a simple power-law model are used to obtain integral expressions for signal magnitude. Integral expressions can be simplified by approximating a thin excited slice or complete excitation of the Couette cell depending on experimental parameters. With simple data acquisition and analysis procedures employed, our measurements of the flow behavior indices of non-Newtonian xanthan gum dispersions are in close agreement with conventional rheological magnetic resonance measurements.

Thermo diffusion impacts on the flow of second grade fluid with application of (ABC), (CF) and (CPC) subject to exponential heating

The aim of this article is to investigate the exact solution by using a new approach for the thermal transport phenomena of second grade fluid flow under the impact of MHD along with exponential heating as well as Darcy’s law. The phenomenon has been expressed in terms of partial differential equations, then transformed the governing equations in non-dimentional form. For the sake of better rheology of second grade fluid, developed a fractional model by applying the new definition of Constant Proportional-Caputo hybrid derivative (CPC), Atangana Baleanu in Caputo sense (ABC) and Caputo Fabrizio (CF) fractional derivative operators that describe the generalized memory effects. For seeking exact solutions in terms of Mittag-Leffler and G-functions for velocity, temperature and concentration equations, Laplace integral transformation technique is applied. For physical significance of various system parameters on fluid velocity, concentration and temperature distributions are demonstrated through various graphs by using graphical software. Furthermore, for being validated the acquired solutions, accomplished a comparative analysis with some published work. It is also analyzed that for exponential heating and non-uniform velocity conditions, the CPC fractional operator is the finest fractional model to describe the memory effect of velocity, energy and concentration profile. Moreover, the graphical representations of the analytical solutions illustrated the main results of the present work. Also, in the literature, it is observed that to derived analytical results from fractional fluid models developed by the various fractional operators, is difficult and this article contributing to answer the open problem of obtaining analytical solutions the fractionalized fluid models.

Transient three-dimensional magnetohydrodynamic flow of heat and mass transfer of a Casson nanofluid past a stretching sheet with non-uniform heat source/sink, thermal radiation and chemical reaction

This study considered the effect of chemical reaction on transient magnetohydrodynamic flow of heat and mass transfer of a Casson nanofluid past a stretching sheet with non-uniform Heat Source/Sink. The highly nonlinear partial differential equations governing the fluid flow alongside its boundary conditions are formulated and suitable similarity variables are introduced to transform the nonlinear partial differential equations into a set of coupled ordinary differential equations. The results revealed that as the Casson fluid parameter increases, the yield stress reduces thereby reducing the velocity, temperature, and concentration profiles. Magnetic parameter, chemical reaction parameter, stretching ratio parameter and unsteadiness parameter can be used to adjust the fluid velocity, temperature and concentration distributions. The effects of local skin friction coefficients, local Nusselt and Sherwood numbers are also shown and considered using tables. The results revealed that the unsteadiness parameter, Casson fluid parameter and magnetic parameter reduces the momentum boundary layer thickness along x and y direction. The work provides physical insight into the thermo-fluidic flow phenomena of Casson nanofluid under the impacts of magnetic field, internal heat generation and chemical reaction.

Numerical investigations on fluid characteristics around the bottom-fixed aquacultural farm

Offshore aquacultural farms are world widely booming in recent years. The bottom-fixed aquacultural farm gains more and more attention because of the large volume and great strength. This study numerically investigates the fluid velocity distribution characteristic around the bottom-fixed aquacultural farm, which is of great importance for fish welfare and pollutant diffusion. The numerical model is developed based on the porous media model for the nets and the rigid walls for the fixed frame. The k-omega turbulence model and the finite volume method are employed to solve the Navier-Stokes equations. The flow velocity distributions around and inside the farm in the varied current velocity are analyzed. The vertical and horizontal flow velocity distributions in various current directions with different net solidities are investigated in detail. Results demonstrated that the configurations of trusses, vertical and horizontal columns of the farm and the interaction with the nets result in complex velocity distributions inside and around the farm. The velocity attenuations at different depths are quite different in uniform and non-uniform currents. The velocity distributions in different attack angles of the flow provide valuable suggestions on the arrangement and layout of the multiple farms.

Application of coarse-graining for large scale simulation of fluid and particle motion in spiral jet mill by CFD-DEM

Spiral jet milling is commonly used for size reduction of high value particulate solids, such as pharmaceutical ingredients, for which low contamination is critical. The mill utilises high-pressure gas nozzles to form an internal vortex and induce particle breakage through inter-particle collisions. Due to the centrifugal flow field, the particles can move radially inwards towards the mill centre and escape the mill only when their size is sufficiently reduced for the fluid drag to exceed the centrifugal force. Large particles move radially towards the outer wall and form a dense particle bed. The bed itself circulates in the milling chamber due to the induced effect of the inclined gas jets. In this study, we analyse the implementation of a coarse-graining (CG) approach on a coupled Computational Fluid Dynamic-Discrete Element Method simulation. Along with the actual particle size, four CG scale cases are compared (CG-2, CG-4, CG-8 and CG-10). To analyse the success of the approach in predicting the dynamics of fluid and particle motion, the characteristic features of the particle bed and fluid field, i.e. the fluid and particle velocity distributions and dissipated energy through particle collisions are analysed. There is good agreement between the original particle size and the two smallest scaled cases (CG-2, CG-4) for the above characteristics. However, modelling the lean phase is less successful, as there are fewer particles that reside there at any given time. There is also good agreement between these three cases in terms of dissipated energy through particle collisions. An average value for dissipated energy of 0.6 mJ is recorded for each of the three lowest cases. This proves beneficial for simulation time required, as the particle number is reduced 2-fold and 4-fold, respectively, and interparticle collision rate is reduced 60% each time. Application of the Coarse Grain method in a spiral jet mill using coupled Computational Fluid Dynamics and Discrete Element Method Modelling. Top: Original particle size system and four scaled systems. Bottom: Resulting temporal average dissipated energy through interparticle collisions and particle wall collisions. • Coarse graining method is applied in the spiral jet mill using a CFD-DEM framework. • Particle and fluid motion is similar in the bed at smaller scales. • Insufficient particles were present in the lean phase to model the original system. • Temporal dissipated energy remained constant for low coarse grain numbers.

Unsteady oblique stagnation-point flow and heat transfer of fractional Maxwell fluid with convective derivative under modified pressure field

Unsteady oblique stagnation-point flow and heat transfer of fractional Maxwell fluid with convective derivative towards an oscillating tensile plate are discussed in this paper. The fractional operator is introduced to material derivative for the first time to obtain a newly defined constitutive equation of Maxwell fluid. The Fourier's law is modified accordingly. The pressure gradient is innovatively obtained by solving the differential equation, which bases on the momentum equation away from the plate. Furthermore, the numerical solutions are acquired by virtue of the finite difference method combined with L1-algorithm. It turns out to be convergent through constructing numerical example. The influence of related parameters on the velocity and temperature are performed graphically in detail. Results show that the fluid velocity and temperature distributions tend to periodic oscillation near the plate. Both the velocity and the temperature reduce with the augment of fractional derivative parameters, which indicates the velocity and the temperature boundary layer become thinner. The smaller velocity relaxation time parameter leads to enhanced velocity, meaning that the pressure promotes the fluid velocity. It is evident that all the temperature curves have a tendency to increase first and then decrease with the diverse parameters due to the thermal relaxation characteristic.

SIMULATION STUDY OF HYDRODYNAMIC CAVITATION IN THE ORIFICE FLOW

Hydrodynamic cavitation is a phenomenon that can be used in the water treatment process. For this purpose, venturis or orifices varying in geometry are used. Studying this phenomenon under experimental conditions is challenging due to its high dynamics and difficulties in measuring and observing the phase transition of the liquid. For this reason, the CFD method was used to study the phenomenon of hydrodynamic cavitation occurring in water flow through the orifice and then analyze flow parameters for different boundary conditions. The research was performed for four different orifice geometries and two defined fluid pressure values at the inlet, based on a computational 2D model of the research object created in Ansys Fluent software. As a result of the numerical simulation, the distribution of fluid velocity and pressure and volume fraction of the gas phase were obtained. A qualitative and quantitative analysis of the phenomenon of hydrodynamic cavitation under the considered flow conditions was conducted for the defined orifice geometries. The largest cavitation zone and thus the largest volume fraction of the gas phase was obtained for the orifice diameter of 2 mm with a sharp increase in diameter. However, the geometry with a linear change in diameter provided the largest volume fraction of the gas phase per power unit.

Two-Phase Flow of Eyring–Powell Fluid with Temperature Dependent Viscosity over a Vertical Stretching Sheet

In this work, the mixed convection flow of non-Newtonian Eyring–Powell fluid with the effects of temperature dependent viscosity (TDV) were studied together with the interaction of dust particles under the influence of Newtonian Heating (NH) boundary condition, which assume to move over a vertical stretching sheet. Alternatively, the dusty fluid model was categorized as a two-phase flow that consists of phases of fluid and dust. Through the use of similarity transformations, governing equations of fluid and dust phases are reduced into ordinary differential equations (ODE), then solved by efficient numerical Keller–box method. Numerical solution and asymptotic results for limiting cases will be presented to investigate how the flow develops at the leading edge and its end behaviour. Comparison with the published outputs in literature evidence verified the precision of the present results. Graphical diagrams presenting velocity and temperature profiles (fluid and dust) were conversed for different influential parameters. The effects of skin friction and heat transfer rate were also evaluated. The discovery indicates that the presence of the dust particles have an effect on the fluid motion, which led to a deceleration in the fluid transference. The present flow model can match to the single phase fluid cases if the fluid particle interaction parameter is ignored. The fluid velocity and temperature distributions are always higher than dust particles, besides, the opposite trend between both phases is noticed with β. Meanwhile, both phases share the similar trend in conjunction with the rest factors. Almost all of the temperature profiles are not showing a significant change, since the viscosity of fluid is high, which can be perceived in the figures. Furthermore, the present study extends some theoretical knowledge of two-phase flow.

Electrical, Diffusional, Hydraulic, and Geometrical Tortuosity Anisotropy Quantification Using 3D Computed Tomography Scan Image Data

Summary Sedimentary rocks display complex spatial distribution of both pore space and solid components, impacting the directional dependence of physical phenomena such as electrical conduction, fluid flow, heat transfer, and molecular diffusion. The complexity of the pore space is often quantified by the concept of tortuosity, which measures the sinuosity of the connecting paths in the pore space. Tortuosity is an important quantity in formation evaluation as it impacts petrophysical properties such as permeability and formation factor. However, the existence of various techniques can lead to nonuniqueness in assessment of tortuosity. Furthermore, spatial variation of the solid components of the rocks occurring at the core-scale domain reflected in the connectivity and distribution of the minerals is typically not quantified. The objectives of this paper are (a) to quantify tortuosity and tortuosity anisotropy of porous media through estimation of electrical, diffusional, hydraulic, and geometrical tortuosity at the pore scale and core scale and (b) to compare electrical, diffusional, hydraulic, and geometrical tortuosity. We estimate tortuosity in the pore space of microcomputed tomography (micro-CT) scan images and in the most connected and abundant solid phase of whole-core CT scan images. We conduct numerical simulations of electric potential distribution, diffusion, and fluid flow and velocity distribution to estimate electrical, diffusional, and hydraulic tortuosity, respectively. To calculate geometrical tortuosity, we use the segmented pore space from micro-CT scan images to extract a pore network model and compute the shortest path of all opposing pores of the samples. Finally, tortuosity values obtained with each technique are used to assess the anisotropy of the samples. We applied the documented workflow to core- and pore-scale images. The CT scan images in the core-scale domain belong to a siliciclastic formation. Micro-CT scan images in the pore-scale domain were obtained from Berea Sandstone, Austin Chalk, and Estaillades limestone formations. We observed differences in estimates of direction-dependent electrical, diffusional, hydraulic, and geometrical tortuosity for both types of images. The highest numerical differences were observed when comparing streamline electrical and hydraulic tortuosity with diffusional tortuosity. The observed differences were significant in anisotropic samples. Differences in tortuosity estimates can impact the outcomes of rock physics models for which tortuosity is an input. The documented comparison provides insight in the selection of techniques for tortuosity estimation. Use of core-scale image data provides semicontinuous estimates of tortuosity and tortuosity anisotropy, which are typically not attainable using pore-scale images. Additionally, the semicontinuous tortuosity anisotropy estimates from whole-core CT scan images provide a tool for selection of best locations to take core plugs.