Fluid Flow Analysis Research Articles

Design and research of bone repair scaffold based on two-way fluid-structure interaction

Background and objectivePorous bone repair scaffolds are an important method of repairing bone defects. Fluid flow in the scaffold plays a vital role in tissue differentiation and permeability and fluid shear stress (FSS) are two important factors. The differentiation of bone tissue depends on the osteogenic differentiation of cells, FSS affects cell proliferation and differentiation, and permeability affects the transportation of nutrients and metabolic waste. Therefore, it is necessary to better understand and analyze the FSS on the cell surface and the permeability of the scaffold to obtain better osteogenic performance. MethodsIn this study, computational fluid dynamics (CFD) was used to analyze fluid flow in the scaffold. Three structures and nine scaffold unit cell models were designed and the cell models were loaded onto the scaffold surface. Considering cell deformability, the two-way fluid-structure interaction (FSI) method was used to evaluate the FSS on the cell surface. ResultsThe simulation results showed that as the pore size of the scaffold increases, its permeability increases and the FSS decreases. The FSS received on the cell surface was much larger than scaffold surface. Moreover the FSS on the cell surface was distributed in steps. ConclusionsThe results showed the permeability of all models matches that of human bone tissue. Based on the cell surface FSS as the criterion, it was found that the spherical-560 scaffold exhibited the best osteogenic performance. This provided a strategy to design a better bone repair scaffold from biological aspects.

Perturbation Solution for One-Dimensional Flow to a Constant-Pressure Boundary in a Stress-Sensitive Reservoir

Most analyses of fluid flow in porous media are conducted under the assumption that the permeability is constant. In some “stress-sensitive” rock formations, however, the variation of permeability with pore fluid pressure is sufficiently large that it needs to be accounted for in the analysis. Accounting for the variation of permeability with pore pressure renders the pressure diffusion equation nonlinear and not amenable to exact analytical solutions. In this paper, the regular perturbation approach is used to develop an approximate solution to the problem of flow to a linear constant-pressure boundary, in a formation whose permeability varies exponentially with pore pressure. The perturbation parameter αD is defined to be the natural logarithm of the ratio of the initial permeability to the permeability at the outflow boundary. The zeroth-order and first-order perturbation solutions are computed, from which the flux at the outflow boundary is found. An effective permeability is then determined such that, when inserted into the analytical solution for the mathematically linear problem, it yields a flux that is exact to at least first order in αD. When compared to numerical solutions of the problem, the result has 5% accuracy out to values of αD of about 2—a much larger range of accuracy than is usually achieved in similar problems. Finally, an explanation is given of why the change of variables proposed by Kikani and Pedrosa, which leads to highly accurate zeroth-order perturbation solutions in radial flow problems, does not yield an accurate result for one-dimensional flow.Article HighlightsApproximate solution for flow to a constant-pressure boundary in a porous medium whose permeability varies exponentially with pressure.The predicted flowrate is accurate to within 5% for a wide range of permeabilityvariations.If permeability at boundary is 30% less than initial permeability, flowrate will be 10% less than predicted by constant-permeability model.

The numerical simulation and sensitivity analysis of a non-Newtonian fluid flow inside a square chamber exposed to a magnetic field using the FDLBM approach

This paper simulated the free convective heat transfer (CHT) and generation of entropy (GOE) of a non-Newtonian fluid (NNF) in a square chamber using the FDLBM approach. The NNF is modeled by the power-law method. A magnetic field (MF) is able to take different angles which has affected the chamber. A hot square barrier exists in the middle of the chamber. The side edges of the chamber have sinusoidal temperature profiles, and the top and bottom sides are insulated. The effective studied parameters include the Hartmann number (Ha), angle of MF, exponential function index, and the aspect ratio (AR) of the hot barrier. The results of simulation disclosed that shear-thinning NNF has the highest CHT and shear-thickening NNF has the lowest GOE. Increasing the AR of the hot barrier led to an increase in the Nusselt number (Nu) and GOE and a decrease in the Bejan number (Be). Increasing the angle of the MF at small ARs with Newtonian fluid increases the Nu. Increasing the Ha from 0 to 40 in shear-thinning NNF, shear-thickening NNF, and Newtonian fluid reduced CHT by 43%, 15%, and 43%, respectively. Increasing the Ha also reduces the GOE by 27% for Newtonian fluid and 763% and 4% shear-thinning NNF and shear-thickening NNF, respectively. Eventually, a relation is proposed for the mean Nu, GOE, and Be.

Heat and Fluid Flow Analysis and ANN-Based Prediction of A Novel Spring Corrugated Tape

A circular tube fitted with novel corrugated spring tape inserts has been investigated. Air was used as the working fluid. A thorough literature review has been done and this geometry has not been studied previously, neither experimentally nor theoretically. A novel experimental investigation of this enhanced geometry can, therefore, be treated as a new substantial contribution in the open literature. Three different spring ratio and depth ratio has been used in this study. Increase in thermal energy transport coefficient is noticed with increase in depth ratio. Corrugated spring tape shows promising results towards heat transfer enhancement. This geometry performs significantly better (60% to 75% increase in heat duty at constant pumping power and 20% to 31% reduction in pumping power at constant heat duty) than simple spring tape. This paper also presented a statistical analysis of the heat transfer and fluid flow by developing an artificial neural network (ANN)-based machine learning (ML) model. The model is evaluated to have an accuracy of 98.00% on unknown test data. These models will help the researchers working in heat transfer enhancement-based experiments to understand and predict the output. As a result, the time and cost of the experiments will reduce. The results of this investigation can be used in designing heat exchangers.

Fluid flow and permeability analysis of tight gas carbonate reservoir rocks using fractures and dynamic data

The porosity, permeability, rock material and fracture networks of the newly discovered tight carbonate reservoir rock, the Early Cretaceous Sarmord Formation in Zagros basin are examined. The methods used to investigate the formation are rock cores, micro-resistivity image logs, drill stem tests, drilling fluid data, petrophysical wireline data and drilled cutting samples.The analysed data show that the Sarmord Formation is characterized by extensive open and partially open macro-fractures formed by the local stress from fault and fold propagation. These fractures are sub-vertical with an average dip of 73°, fracture aperture of 0.44 mm and persistence (length) of 11.0 cm. The dominant strike of the fractures is NE-SW, parallel to the observed faults and perpendicular to the main Miran West structure.The vast majority of reservoir porosity was found to be in the rock matrix, with the fractures having very limited impact (average fracture porosity is 0.032%) on porosity. In contrast the fracture permeability averages 240 mD which is four orders of magnitude greater than the matrix permeability. As a result, the inter-connected fractures create effective fluid flow pathways and enhanced hydrocarbon migration perpendicular to the fold structure. Faulting associated with the field structure led to fault damaged zones which act as zones of inter-connected fractures with higher permeability and preferential fluid flow pathways. It is demonstrated that the fracture permeability is driven by the fracture aperture and spacing, whilst the fracture persistence has limited control on permeability.The findings of this study highlight that the importance of fractures and faults on reservoir's quality in tight gas bearing rocks. The network of inter-connected fractures, provide the fluid flow which control the permeability. In contrast the matrix controls the pore spaces and the hydrocarbon storage. This work emphasizes the importance of understanding the impact of structural geology in tight carbonate reservoirs.

Galerkin finite element modeling of thermohaline fluid in an inclined cavity

The knowledge of the behavior of thermo-solute in a confined space shall open up many application areas in control process. Flow analysis of a Thermohaline fluid inside a square cavity inclined at angle ‘φ0’ with X-axis under steady state conditions has been investigated has been investigated.. The equations are modified with respect to rotational symmetry of groups. The resulting partial differential equations are modelled using Finite Element Technique. Also we have established a set of shape functions applicable to fourth order partial differential equations. Shape functions and the corresponding surfaces are characterized with respect to its properties. Algorithm has been developed for the computation. This model can be extended to analysis of largescale double diffusive convection subjected to complex boundaries.

Numerical Analysis of Fluid Flow and Heat Transfer by Means of a Unified Model in a Direct Current Electric Arc Furnace

Herein, a unified 2D axially symmetric model coupling the plasma arc and molten bath in a direct current electric arc furnace is established, with the physical phenomena at the plasma arc/molten bath interface to be confronted by the “local thermodynamic equilibrium diffusion approximation” method. After ensuring model validation and grid independence test, the fluid flow and heat transfer processes are analyzed. The numerical investigation reveals that in terms of the relative importance of driving forces in the molten bath, an anticlockwise eddy is formed at the molten bath center driven by electromagnetic force, whereas a clockwise eddy is formed near the lateral part of the molten bath driven by buoyancy force. Regarding the distribution of heat flux, the convection–conduction and radiation heat govern the rate of heat transfer from the plasma arc to the molten bath. In addition, for larger arc current, higher arc power in the plasma arc region and higher heating rates in the molten bath are obtained when the arc length is held constant; for shorter arc length, lower arc power in the plasma arc region but higher heat transfer efficiency in the molten bath is attained when the arc current is held constant.

Analysis of Fluid Flow in the Sealing Gap of Radial Shaft Seals and Elastic Deformation of the Sealing Surface

Abstract The function of a radial shaft seal is based on interactions between the sealing edge and the shaft counterface. To better understand these mechanisms, a look inside the sealing contact was taken. The procedure and the testing facility are presented in this article. In addition, a research methodology was developed to systematically analyze the fluid flow and the distortion of the sealing surface of shaft seals. The results of the test procedure are documented in an evaluation matrix that allows the comparison of sealing systems with different worn sealing edges. For example, the tests show an influence of the rotation direction of the shaft during running-in on the formation of leakage channels or oil collecting chambers within the sealing contact.

Aspects Regarding the Dynamic Behavior of a Hydraulic Cylinder

Abstract This paper deals with hydraulic cylinders with and without end position cushioning. The reduction of the velocity at the end of the stroke is important in order to preserve the structural integrity and to avoid undesirable motion of the load. The mathematical model of such a hydraulic cylinder is shown, as well as the Matlab functional diagram for the system. It is also revealed the role of the working fluid, considering the actual recommendations regarding the biodegradable substances. It was considered both mineral base liquids and vegetable base liquids. The functional diagram offers the possibility to view for the hydraulic system the variation of the speed, flow rate, rate and stroke of the piston, in both cases: with and without end position cushioning. Is also shown a CFD analysis of fluid flow through the supply/outlet connections of the hydraulic cylinder.

An analysis of Bingham Fluid and Jeffrey Fluid Flow in a Horizontal Channel with Plug Flow and Heat Transfer

A mathematical model is constructed for MHD flow of Bingham fluid and Jeffrey fluid in a horizontal porous space with heat transfer effect. The dimensionless governing equations for this problem are solved analytically and expressions for velocity and temperature field are presented. Further, impacts of physical parameters on flow and heat transfer charcteristics has been studied and discussed graphically. It is found that increasing viscosity ratio enhances velocity and temperature field whereas thermal conductivity ratio gives the reverse effect. Increasing magnetic field parameter tends to suppress fluid velocity significantly whilst mixed behavior shown in temperature distribution. Velocity of the fluid increased considerably with increasing material parameter whereas the reverse trend can be noticed in temperature distribution. Further, it is observed that pressure gradient influenced significantly on velocity and temperature field. Increasing magnetic parameter reduces mass flow rate whereas it shows opposite trend in shearstress distribution.

Thermo-magnetic-fluid dynamics analysis of an ONAN distribution transformer cooled with mineral oil and biodegradable esters

This work introduces a coupled electromagnetic, thermal and fluid flow analysis of an oil-natural air-natural distribution transformer in order to study the changes in the heat dissipation performance when a biodegradable ester is used to cool the device instead of mineral oil. The transformer has a rated power of 315kVA and a voltage ratio of 13.2kV / 0.4kV. The heat losses in the magnetic core and the windings are computed with the ANSYS® Maxwell software and they are transferred as volume heat source terms to compute the heat conduction. The natural convection of the fluid flow is taken into account using a temperature-dependent density. The heat conduction through the solid walls and radiators panels are also considered. The thermo–hydraulic problem is solved with the software Code_Saturne. Data from experimental tests carried out with mineral oil are used to validate the numerical simulations. Equivalent and anisotropic thermal conductivities in the core and the windings are calculated both with a semi-analytic procedure and finite element simulations to simplify the heat conduction model in the active parts. It is found that, after reaching a steady state, the transformer cooled with the ester shows a temperature difference between specific locations at the top and the bottom higher than that cooled with mineral oil. The magnetic core and the windings also work hotter when ester is used. Finally, the analysis of the flow through the cooling ducts of the windings confirms that the oil velocity is, on average, 25% higher than the ester one.

Analytical studies on deposition and entrainment present in the Venturi nozzle two-phase flow

The syngas purification is a basic problem in the gas production process through the biomass gasification. This issue is important due to the use of the Venturi scrubbers in the syngas cleaning process. As it is commonly known, syngas is an alternative for the coal and using syngas instead of the coal leads to ‘clean energy’ generation. The paper concerns the analytical research studies on two-phase fluid flow pattern in Venturi’s throat. The uniform coverage of Venturi’s cross-section with small droplets plays a significant role in the dust particles collection and chemicals removal as Venturi’s cleaning efficiency mostly depends on this operation parameter. Therefore, the analysis of the two-phase fluid flow with respect to a droplet deposition and entrainment was carried out. Based on these research studies, it is possible to determine the variation of the liquid superficial velocity in the core of the flow and within the liquid wall film, the length at which the droplet entrainment starts to occur, the liquid fraction variation with Venturi’s throat length and diameter. The obtained analytical model, which is introduced in the paper, was validated with the use of the experimental data available in the literature.

Finite Element Analysis of Fluid Flow through the Screen Embedded between Parallel Plates with High Reynolds Numbers

This paper provides numerical estimation of Newtonian fluid flow past through rectangular channel fixed with screen movable from 10° to 45° by increasing the Reynolds number from 1000 to 10,000. The two-dimensional incompressible Navier Stokes equations are worked out making use of the popular software COMSOL MultiPhysics version 5.4 which implements the Galerkin’s least square scheme to discretize the governing set of equations into algebraic form. In addition, the screen boundary condition with resistance coefficient (2.2) along with resistance coefficient 0.78 is implemented along with slip boundary conditions applied on the wall. We engaged to find and observe the relationship between the optimum velocity, drag force applied by the screen, and pressure occurred in the channel with increasing Reynolds number. Because of the linear relationship between the optimum velocities and the Reynolds number, applying the linear regression method, we will estimate the linear equation so that future prediction and judgment can be done. The validity of results is doing with the asymptomatic solution for stream-wise velocity at the outlet of the channel with screens available in the literature. A nondimensional quantity, i.e., ratio from local to global Reynolds number Re x / Re , is introduced which found stable and varies from -0.5 to 0.5 for the whole problem. Thus, we are in the position to express the general pattern of the velocity of the particles as well as the pressure on the line passing through the middle of the channel and depart some final conclusion at the end.

Second law analysis of MHD third-grade fluid flow through the microchannel

The present study analyses the phenomena of entropy generation of magneto third-grade fluid flow through the microchannel. The significance of Joule heating, viscous heating and internal heat source is also scrutinised. The non-dimensional forms of the corresponding governing equations of the physical phenomenon with the associated boundary conditions for third-grade fluid flow and heat transfer has been solved using finite element method. The impact of various parameters on the flow and heat transfer behaviour, entropy generation and Bejan number is explained using graphs. The obtained results are examined through the plots. The results showed that an increase in the fluid parameter reduces the activity of the fluid flow and, as a result, the temperature is diminished. An enhancement in fluid motion and temperature is obtained by increasing the viscosity index. We noted that the effect of Hartmann number on the rate of local entropy generation and Bejan number is sinusoidal in nature.

An analytical study on fluid flow characteristics for flow within a microchannel of rectangular cross section

The present work considers fluid flow analysis within a microchannel of rectangular cross section with different exact and approximate analytical techniques. Thus, velocity slip at the solid wall of the channel is considered. The slip flow is transformed to a no-slip flow with some minor modifications by applying an average slip velocity. The flow is represented by the Navier-Stokes equation exposed to slip boundary conditions. The governing equation is solved considering separation of variables method (SOV) as an exact method and, Integral and Variational methods as approximate methods. The Poiseuille number and slip coefficient are also determined for each method. The present prediction agrees well with available literature. To predict accuracy level of all the techniques, the results are presented in a comparative scale along with numerical prediction. It is observed that the accuracy level for the velocity profile obtained in each technique depends on the aspect ratio where as for the prediction of Poiseuille number and slip coefficient, all the technique show less dependency on the aspect ratio.

An investigation of the aerodynamic parameters for Solar Plane wing profile using CFD modelling

The technology of solar-powered aerial vehicles requires enormous financial support and further development. For this purpose, the computational fluid dynamic can be used. In order to carry out necessary analyses and model development in this research, ANSYS Fluent software was used. Using the first version of the AGH Solar Plane model, preliminary analysis of lift, drag and tearing off the stream were performed. Numerical experiments made it possible to verify many various profiles and final selection that the best suits the target model. Through these studies, it was also possible to analyse fluid flow at various speeds and angles of attack. This provided an insight into important aspects of vehiclesaerodynamic design, which should be taken into account when making the second model version. At this stage, the classical and laminar - Wortmann aerodynamic profiles were selected on the basis of the aerodynamic perfection criterion. Moreover, four new geometries were prepared on which the flattening of upper surfaces (for fixing solar panels) was tested. The results of the numerical analysis were validated in the aerodynamic tunnel using particle image velocimetry method. Taking into account all analyses, a number of recommendations have been prepared that will be implemented in order to create an aircraft, which meets all target requirements. Some of these hints were: testing new ways of connecting the wing to the nacelle, which would reduce the drag as well as considering the usage of winglets in order to minimize induced drag.

Double-Layer Metal Foams for Further Heat Transfer Enhancement in a Channel: An Analytical Study

A local thermal non-equilibrium analysis of heat and fluid flow in a channel fully filled with aluminum foam is performed for three cases: (a) pore density of 5 PPI (pore per inch), (b) pore density of 40 PPI, and (c) two different layers of 5 and 40 PPI. The dimensionless forms of fully developed heat and fluid flow equations for the fluid phase and heat conduction equation for the solid phase are solved analytically. The effects of interfacial heat transfer coefficient and thermal dispersion conductivity are considered. Analytical expressions for temperature profile of solid and fluid phases, and also the channel Nusselt number (NuH) are obtained. The obtained results are discussed in terms of the channel-based Reynolds number (ReH) changing from 10 to 2000, and thickness ratio between the channel height and sublayers. The Nusselt number of the channel with 40 PPI is always greater than that of the 5 PPI channel. It is also greater than the channel with two-layer aluminum foams until a specific Reynolds number then the Nusselt number of the channel with two-layer aluminum foams becomes greater than the uniform channels due to the higher velocity in the outer region and considerable increase in thermal dispersion.

A Fluid Flow Data Set for Machine Learning and its Application to Neural Flow Map Interpolation.

In recent years, deep learning has opened countless research opportunities across many different disciplines. At present, visualization is mainly applied to explore and explain neural networks. Its counterpart-the application of deep learning to visualization problems-requires us to share data more openly in order to enable more scientists to engage in data-driven research. In this paper, we construct a large fluid flow data set and apply it to a deep learning problem in scientific visualization. Parameterized by the Reynolds number, the data set contains a wide spectrum of laminar and turbulent fluid flow regimes. The full data set was simulated on a high-performance compute cluster and contains 8000 time-dependent 2D vector fields, accumulating to more than 16 TB in size. Using our public fluid data set, we trained deep convolutional neural networks in order to set a benchmark for an improved post-hoc Lagrangian fluid flow analysis. In in-situ settings, flow maps are exported and interpolated in order to assess the transport characteristics of time-dependent fluids. Using deep learning, we improve the accuracy of flow map interpolations, allowing a more precise flow analysis at a reduced memory IO footprint.

Network broadcast analysis and control of turbulent flows

Abstract

Simulations of micropolar nanofluid-equipped natural convective-driven flow in a cavity

PurposeThis paper aims to focus on the natural convective flow analysis of micropolar nanofluid fluid in a rectangular vertical container. A heated source is placed in the lower wall to generate the internal flow. In further assumptions, the left/right wall are kept cool, while the upper and lower remaining portions are insulated. Free convection prevails in the regime because of thermal difference in-between the lower warmer and upper colder region.Design/methodology/approachThe physical setup owns mathematical framework in-terms of non-linear partial differential equations. For the solution purpose of the differential system, finite volume method is adopted. The interesting features of the flow along with thermal transportation involve both translational and rotational movement of fluid particles.FindingsPerforming the simulations towards flow controlling variables the outputs are put together in contour maps and line graphs. It is indicated that the variations in flow profile mass concentration and temperature field augments at higher Rayleigh parameter because of stronger buoyancy effects. Higher viscosity coefficient implies decrease in flow and thermal transportation. Further, the average heat transfer rate also grows by increasing both the Rayleigh parameter and heated source length.Originality/valueTo the best of the authors’ knowledge, no such study has been addressed yet. Further, the results are validated by comparing with previously published work.