Fluid Flow Velocity Research Articles

Analysis of crude oil effect for CO2 corrosion of carbon steel - A rotating cylinder electrode approach

Crude oils, especially heavy crude oils, are rarely used in multiphase-flow loop experiments because of the experimental difficulties. Variations in the tested fluid viscosity, emulsification processes, water cut (WC), flow velocity and flow patterns, interactions between the crude oil and brine, the difficulty in obtaining metal/environment electrical continuity by covering the metal surface with crude oil, and the difficulty of selecting appropriate instrumentation to monitor the experiment are some of these problems. Studies indicate that crude oil can change the brine chemistry and influence the preferential oil/water metal-surface wettability, which impacts the corrosion process. Based on the assumption that corrosion would only occur when free water is separated from an emulsion, the risks could be reduced by transporting emulsified crude oils. However, as the solubility of water in crude oil is low, free water can be formed at the bottom of horizontal pipelines when the emulsion destabilizes, causing an increase in corrosion processes. In previous author’s studies, carbon-steel flow-induced corrosion (FIC) tests were carried out in a multiphase-flow corrosion loop containing a liquid phase of brine plus light or heavy crude oils (WC 80) with a gaseous phase of CO2. Higher corrosion rates for heavy crude oil were observed, which were not expected. No experimental studies in multiphase-flow corrosion loops using heavy crude oils in CO2-brine solution were found in the literature. In attempting to understand the reason for the higher aggressiveness of the heavy crude oil, rotating cylinder electrode (RCE) tests were performed under the same conditions used in the multiphase-flow loop.

CFD Analysis of an Aircraft Turbofan Engine Combustion Process and the Effect on Turbine

In this paper, a two-dimensional computational fluid dynamics (CFD) study of Turbofan engine is presented using the ANSYS Fluent program, the navier–stokes equations is used for analysis, including a two-dimensional and symmetrical drawing of both the combustion chamber and in a 1.5 Stage Axial Flow Turbine. A GE-90 turbofan engine nacelle was used with Naca 63-412 type blades were used for the analysis of the flow on the turbine blades. Combustion chamber simulations were carried out using a previous study. The computational results were compared with other studies on the Exergetic analysis of a GE-21 turbojet engine. The GE-21 engine had a combustion chamber temperature of 2900 K, while the GE-90 engine had a temperature of around 2706 K. The previous study considered the velocity of fluid flow to be 200 m/s, whereas the velocity of flow in this study was 209 m/s as determined in the part of analysis and result.

Investigation on flow resistance of fluid in permeable asphalt mixture

Flow resistance distribution of fluid is the basis of comprehensively grasping the permeability of permeable asphalt mixture. This study aimed to investigate the flow resistance of fluid in permeable asphalt mixture. Considering the influence of anisotropy of permeable asphalt mixture, the vertical and transverse permeability tests of five types of permeable asphalt mixture were carried out using multidirectional permeability test instrument developed by our research group. The fitting equation of permeability was determined by comparing Darcy's law with Forchheimer equation. Moreover, the flow resistance is usually considered as an effective parameter to reveal the structural permeability. The connective void content of permeable asphalt mixture is important to calculate flow resistance. Accordingly, it is necessary to obtain the transverse and vertical connective voids of the asphalt mixture considering the influence of anisotropy. Therefore, a program for calculating the multi-directional connective void content was developed based on the theory of projection reconstruction. On this basis, a pore throat model was applied to reveal the variation of flow resistance of asphalt mixture. The results show that the weight of inertia resistance and viscous resistance is different in various seepage velocities. The viscous resistance is dominant when the fluid flow velocity is less than 0.0087 m/s under experimental conditions, and the inertial resistance is dominant when the fluid flow velocity is greater than 0.0087 m/s. The viscous resistance and inertia resistance of fluid are affected by the anisotropy and structure type of permeable asphalt mixture. When the vertical void content decreases by 3.3%, the corresponding viscous and inertial resistance increase by 7.92 kPa/m and 0.84 kPa/m, respectively. For the transverse void, the viscous and inertial resistance increase by 3.19 kPa/m and 2.02 kPa/m respectively as the content decreases by 3.5%. The influence of void structure of permeable asphalt mixtures on fluid flow is revealed from a microscopic perspective, which can be used to guide the optimization design of gradation of permeable asphalt mixtures.

A Mathematical Investigation of Flow of Third Grade Fluid in Channel Filled with Porous Media with Heat Source

In this study on flow of third grade fluid in channel filled with porous media in the presence of heat generation, the researcher considered and analyzed the effects thermo-physical parameters involved the momentum and energy equations. The nonlinear momentum and energy equations arising from the flow regime is solved analytically using perturbation technique. Explicit expression for the velocity field and energy balance have been obtained Results show that a little increase in the third grade parameterß , Grashof number,G, and the magnetic field parameter,M, reduces the velocity of fluid flow but enhances the temperature of the system greatly.

A Mathematical Approach to Dampening Sea Waves Using Submerged Permeable Breakwater

A wave is an energy that can propagate with a medium; the propagation of a wave moves with respect to time by carrying energy that moves with velocity per unit of time. Sea waves are one of the propagating wave problems that are broken down to produce wave propagation with a relatively inhomogeneous minimum amplitude and speed of sea waves, which have their own difficulties in solving them numerically. This study aims to analyze the stability of wave propagation on submerged breakwaters. This research will approximate the finite discretization of the breakwater domain and then combine it with the Finite Element Method to determine the moving elements of the velocity of fluid flow through a porous submerged breakwater. The research has explained the equation of the inflated wave and the simulated representation displayed on the wave breakdown process, the point that becomes the center of the waves breakdown will give a focused red color indicator meaning there is a change in momentum and potential energy that occurs and then changes the colour of the post-flattering of the sea wave so that the sinking wave breaker is a method to obtain the minimum speed and amplitude values that can be used for coastal engineering.
 

Magnetic Resonance Velocimetry for porous media: sources and reduction of measurement errors for improved accuracy

Nuclear Magnetic Resonance (NMR) is a powerful tool for noninvasively investigating static and dynamic properties of fluids inside complex and opaque structures. Thus, Magnetic Resonance Velocimetry (MRV) allows for the in situ analysis of the local flow velocity of fluids. Such an analysis characterises mass transport properties and helps to validate or improve numerical predictions for porous media. The benefit of such validations is lowered by several problems worsening the measurement accuracy. This publication addresses systematic errors and the influence of noise, which may reduce the accuracy of MRV measurements. Techniques are described to minimise or correct displacement and phase errors. A new multi-echo MRV-sequence is proposed as a compromise between Velocity-to-Noise Ratio (VNR), total measurement time, spatial resolution and displacement errors. For improved VNR, a dual-VENC encoding scheme was used and repetition time T_{text{R}} was optimised. As an example, the proposed MRV sequence was used to measure the three-directional flow velocity of water in an Open Cell Foam (OCF) with 10 pores per inch with three-dimensional isotropic spatial resolution.

Aggregation Volume Estimator–Based Offline Programming Guidance of Magnetic Nanoparticles in the Realistic Rat‐Brain Vasculature Model

Targeted delivery of magnetic nanoparticles (MNPs) to an area of a blood vessel with fluidic flow is hampered by the lack of a suitable real‐time imaging modality for MNPs, the control system complexity, and low targeting performance. Herein, an offline programming guidance (OLPG) scheme for aggregated MNPs is proposed based on a real‐time aggregation volume estimator. The proposed aggregation volume estimator based on a magnetic drug‐targeting simulator reflects volume changes of aggregated MNPs; hence, it can model a magnetic force acting on aggregated MNPs in real time while enhancing targeting performance. The proposed guidance system is evaluated using a simulation testbed and in vitro model of the rat brain, which yields comparable results at different fluid viscosities, flow velocities, target areas, and flow types. The OLPG with the aggregation volume estimator improves targeting performance by 116%–409% compared with the default mode, and by 111%–180% compared to the performance without the aggregation volume estimator. Furthermore, a guidance margin predicts enhanced targeting performance (root‐mean‐square error < 5%) irrespective of the flow environment. The proposed guidance strategy has the potential to overcome the problems caused by the lack of an imaging modality, control‐system complexity, and low targeting performance.

Magnetohydrodynamics analysis of magnetorheological fluid damper

A key feature of magnetorheological fluid is its variability of rheological properties in which upon exposing this fluid, the viscosity of the fluid changes accordingly. Hence this nature can be implemented in various engineering applications. To understand its influence in a magnetorheological (MR) damper, it is essential to study the flow behaviour using computational and numerical methods. The main objective of this work is to estimate the influence of the external magnetic field on the fluid flow velocity inside the damper using magnetohydrodynamic analysis. Finite element analysis, magnetostatic analysis, and magnetohydrodynamic (MHD) analysis have been carried out to investigate the change in the shape of the velocity profile across the flow gap of the monotube MR damper under the various magnitude of magnetic force using the MHD module of ANSYS fluent software. The simulation is conducted by considering laminar, steady-state, and incompressible fluid flow. In finite element analysis, the magnitude of magnetic flux density (MFD) ‘B’ was evaluated at various direct currents. Later, obtained MFD has been applied perpendicular direction to the flow of MR fluid. The effective length of the fluid exposed to the MFD is taken as 2 mm to 28 mm in an overall flow length of 30 mm. The extracted results have shown that the fluid flow velocity reduces with an increase in the magnetic flux density. It has been observed that 10.42 % reduction in velocity upon increasing the magnetic flux density from 0.25 T to 1 T at 75 kPa pressure. The reason for a reduction in velocity is because of variation in the rheological properties of the fluid under the magnetic field, which is very much essential to produce a good damping effect in the MR damper.

A three-dimensional method for morphological analysis and flow velocity estimation in microvasculature on-a-chip.

Three-dimensional (3D) imaging techniques (e.g., confocal microscopy) are commonly used to visualize in vitro models, especially microvasculature on-a-chip. Conversely, 3D analysis is not the standard method to extract quantitative information from those models. We developed the μVES algorithm to analyze vascularized in vitro models leveraging 3D data. It computes morphological parameters (geometry, diameter, length, tortuosity, eccentricity) and intravascular flow velocity. μVES application to microfluidic vascularized in vitro models shows that they successfully replicate functional features of the microvasculature in vivo in terms of intravascular fluid flow velocity. However, wall shear stress is lower compared to in vivo references. The morphological analysis also highlights the model's physiological similarities (vessel length and tortuosity) and shortcomings (vessel radius and surface-over-volume ratio). The addition of the third dimension in our analysis produced significant differences in the metrics assessed compared to 2D estimations. It enabled the computation of new indices, such as vessel eccentricity. These μVES capabilities can find application in analyses of different in vitro vascular models, as well as in vivo and ex vivo microvasculature.

The Chaotic Property of BTA Deep-Hole Machining System under the Effect of Inner Cutting Fluid

To clarify the action mechanism of parameter change on system stability, the chaotic property of BTA deep-hole machining system under the effect of inner cutting fluid was analyzed. According to the kinematic characteristics of the internal cutting fluid and the equation of the moment of momentum of the system, the kinematic equation of the boring bar considering the effect of the internal fluid was established. The critical conditions of chaos were deduced according to the Hamiltonian function and Melnikov function of the plane near-Hamilton system. The mechanism of the liquid filling ratio, cutting fluid flow velocity, and frequency ratio parameters on the system’s critical instability surface is investigated. The correlation and sensitivity of influencing factors, such as filling ratio and frequency ratio, and cutting fluid flow velocity to the sensitivity of system chaos are explored. The results show that in precision machining, the change of liquid filling ratio is positively related to the stability of the system, the change of cutting fluid flow velocity is negatively correlated with the stability of the system, and the change of frequency ratio has no monotonicity effect on the stability of the system. The sensitivity of the chaotic characteristics of the system to each parameter is bounded by the filling liquid ratio h = 0.58. When 0 ≤ h ≤ 0.58, frequency ratio ω ¯ > filling ratio h > cutting fluid flow velocity V0; when 0.58 < h ≤ 1, filling ratio h > frequency ratio ω ¯ > cutting fluid flow velocity V0. These research conclusions can lay a certain theoretical foundation for the analysis, control, and optimization of the complex mechanical behavior of BTA deep-hole machining systems in engineering practice.

A study on the effects of fault architecture on fluid circulation in the Gediz Graben by the finite volume method

It is widely recognized that in geothermal fields, meteoric water infiltrates deep into the subsurface of the earth and then travels through cracks and fractures, returning to the surface as it becomes heated. The patterns of fluid flow are primarily determined by the interaction between forces driven by gravity and pressure gradients. The ultimate forms of fluid flow patterns are primarily determined by the anisotropies of permeability associated with fault zones. In this study, a series of numerical simulations utilizing the finite volume approach were conducted to investigate the effects of fault zone architecture on fluid flow patterns and temperature distributions. Four distinct types of fault zone architecture were created in the simulations, including localized barrier, combined conduit-barrier, localized conduit, and distributed conduit. The results revealed that fault zone architecture has only a minor effect on fluid flow velocities and temperature distributions, except in cases along faults with very high permeabilities. The simulations suggest that this type of 2-D numerical modeling can be easily applied and utilized in other faulted geothermal systems.

Sucrose transport inside the phloem: Bridging hydrodynamics and geometric characteristics

In plants, the delivery of the products of photosynthesis is achieved through a hydraulic system labeled as phloem. This semi-permeable plant tissue consists of living cells that contract and expand in response to fluid pressure and flow velocity fluctuations. The Münch pressure flow theory, which is based on osmosis providing the necessary pressure gradient to drive the mass flow of carbohydrates, is currently the most accepted model for such sucrose transport. When this hypothesis is combined with the conservation of fluid mass and momentum as well as sucrose mass, many simplifications must be invoked to mathematically close the problem and to resolve the flow. This study revisits such osmotically driven flows by developing a new two-dimensional numerical model in cylindrical coordinates for an elastic membrane and a concentration-dependent viscosity. It is demonstrated that the interaction between the hydrodynamic and externally supplied geometrical characteristic of the phloem has a significant effect on the front speed of sucrose transport. These results offer a novel perspective about the evolutionary adaptation of plant hydraulic traits to optimize phloem soluble compounds transport efficiency.

Propagation of wave packets along large-scale background waves

We study propagation of high-frequency wave packets along a large-scale background wave, which evolves according to dispersionless hydrodynamic equations for two variables (fluid density and flow velocity). Influence of the wave packet on evolution of the background wave is neglected, so the large-scale evolution can be found independently of the wave packet's motion. At the same time, propagation of the packet depends in an essential way on the background wave, and it can be considered in a framework of the geometric optics approximation with the use of Hamilton equations for the carrier wave number and the mean co-ordinate of the packet. We derive equations for the carrier wave number as a function of the parameters, which describe the background wave. When they are solved, the path of the packet can be found by simple integration of the Hamilton equation. The theory is illustrated by its application to the problem of propagation of wave packets along expanding a large-scale wave, in which evolution is described by the shallow water equations. In particular, they correspond to the dispersionless limit of the defocusing nonlinear Schrödinger equation, and then the expanding wave can be considered as an expanding cloud of the Bose–Einstein condensate. Reflection of wave packets from upstream flows and their propagation along stationary flows are also discussed. The analytical solutions found for these particular cases agree very well with an exact numerical solution of the nonlinear Schrödinger equation.

The effect of curvature ratio towards the fluid flow characteristics in bend pipe based on numerical methods

Internal flows in pipes are studied in greater depth and comprehensiveness in research. The computation done by using RANS equation. In particular, this study uses two equations turbulence model which is k-ε turbulence model. Mesh with 2×106 element is used because it is a mesh with lowest error. The research focuses on the effect of the curvature ratio (Rc) at the bend on changes in fluid flow characteristics. The Rc variations chosen in this study were 0.01, 0.02, and 0.03. The pipe diameter is 0.01 m, resulting in Rc/D=1, Rc/D=2, and Rc/D=3. At Rc/D=1, the maximum fluid flow velocity is in an area closer to the inner core than the outer core. The fluid velocity distribution is also more even if Rc/D=1 is enlarged. The fluid flow separation appears in the pipe with Rc/D=1, but the fluid flow separation in Rc/D=2 and Rc/D=3 is not visible. The separation is at α=75.96º, while the reattachment location is at x/D=0.014.

Simulation Performance Analysis of Shell and Tube Heat Exchanger Using Comsol Multiphysics 5.6 Software

A heat exchanger is a very important tool in the fields of engineering and industry, especially in energy conversion. This study was aimed at determining the effects of hot and cold fluid flow velocity on the overall heat transfer coefficient (UA) and effectiveness in shell and tube heat exchangers using COMSOL Multiphysics 5.6 software. Another research objective was to observe the phenomena of heat transfer in the shell and tube type heat exchanger at each hot and cold fluid flow velocity. The heat exchanger was designed with a total length of 800 mm and equipped with 18 tubes having a diameter of 2 in and a length of 600 mm. The material used for tube and shell construction was stainless steel. A simulation was carried out using COMSOL Multiphysics 5.6 software to determine the performance of the designed heat exchanger. The results of this simulation indicated that the effects of hot and cold fluid velocity were directly proportional to the value of UA. The heat exchanger have result the smallest UA value of 80.062 W/m2.K, meanwhile the highest UA value of 174.950 W/m2.K. The heat exchanger have result the minimum effectiveness value of 22.305% and the maximum effectiveness value of 52,047%. The second result is phenomenon stating that the surface temperature of the shell and tube would change along with the increasing velocity of both hot and cold fluids, signifying the heat transfer such as conduction and convection from the fluid to the shell or tube.

Thermo-mechanical vibration and stability behaviors of bi-directional FG nano-pipe conveying fluid

This work focuses on the thermo-mechanical modeling of a size-dependent pipe made of bi-directional functionally graded (FG) materials and conveying fluid through its inner wall. The material properties of this FG nano-scale pipe along radial and axial directions are assumed to be separately varying according to the power-law and exponential distributions. The governing equations of the FG nano-scale pipe are derived according to nonlocal strain gradient theory and Hamilton’s principle, and interactions between the size-dependent pipe and its inner fluid are revealed via size-dependent constitutive relation. The frequency response of the pipe and its critical flow velocity are calculated via generalized differential quadrature method. After validation of the proposed model by comparing with previous works, a detailed parametric study is conducted to fully examine the coupling effect of material distribution and various parameters including small size, aspect ratio, boundary constraint, temperature change and flow velocity on the frequency response of the FG nano-pipe. Simultaneously, the critical flow velocity of inner fluid under which the divergence phenomenon appears is also predicted and physically explained in detail. Numerical results show that bi-directional FG design is especially beneficial to improve the stability of FG nano-pipe, which can provide a guide to design advanced micro/nanofluidic devices for bio-engineering applications.

Modeling of the pressure drop effect using membrane distillation in the desalination process

The desalination process using membrane distillation (MD) has recently attracted wide attention in the last few years around the world. Especially, membranes that have an asymmetric geometry, for their performance to filtrate the salt water and the high salt rejection. In this paper, the Langevin dynamics model was adopted as a simulation method to investigate the transport of salt water through the sloping membrane under a pressure drop. The surface of the used membrane is considered as a hydrophilic sloping surface. Thus, the pressure drop effect on the fluid flux was observed, which leads to attracting the salt water into pores that are randomly distributed. The influence of deposition and accumulation of the ions into pores, the incline angle of the membrane surface, and the thickness of the formed layer on the surface were investigated. In addition, the impact of biofouling is caused by the accumulation and the variation of the fluid velocity as a function of pressure drop values. The obtained results show that the relationship between the fluid velocity and the pressing force is a power law. Moreover, the increase in fluid flow velocity in the porous medium is severe in the earlier time regime, but it becomes almost constant in the second regime. However, the time desalination process increases linearly with the pressure drop. Moreover, the accumulation and deposition of ions into the pores cause a decrease in the water flow through the pores resulting in a higher pressure drop in the less inclined direction. Finally, the influence of deposition and accumulation of the salt phase into the pores on the membrane performance was remarked, resulting in a high desalination rate. The obtained results explain the salt water behavior through a porous membrane, which provides ideas for making a high membrane performance.

Theoretical and simulation analysis of the measurement of polarized fluid flow in a circular pipe with electric field excitation

Measurement of conductive fluid flow velocity is essential in applications such as measuring the velocity of water flow in the agriculture sector, sewage water treatment plants, and metal refining industries. This paper proposes a contactless flow measurement device for computing the flow velocity of conductive fluids based on movement of polarized fluid flow. The proposed simulation model of the flow meter can also determine the conductivity of the fluid for varying flow velocity. The obtained simulated results concur with the earlier theoretical studies. Based on the interpretations in the underlying assumptions and physics of a fluid flow under a source of an electric field, it reveals that it is possible to measure a flow velocity of 0.01–10 m s−1 for conductive fluids of 0.1–10 S m−1.

Entrainment probability of coal particle by bubble trailing vortex in coal flotation

Understanding the effect of bubble trailing vortex on particle trajectory is an important precursor for reducing the ash content of coal flotation. Using a high-speed motion acquisition system, we investigated the coal particle trajectory around the cylinder. Two typical trajectories of coal particles around the cylinder were measured. Some particles settled down out of the trailing vortex region while some ones flowed up. The effects of particle density, particle size and fluid flow velocity on the entrainment probability was analyzed. The entrainment probability gradually increased as the coal particle size decreased, increased as the particle density decreased, and increased as the fluid flow velocity increased. The entrainment probability obviously increased as the particle flowability increased independently of particle size, and the increase in the entrainment probability mainly concentrated in the range of particle flowability less than 12.5. The flotation of glass beads was conducted. The flotation recovery increased as the glass bead size decreased, which matched well with the predicted entrainment probability. Our results can provide a valuable insight into the development of flotation technology for cleaner mineral flotation.

Numerical analysis of the effect of a foil-shaped centerbulb on vertical motion and wake on a catamaran sightseeing boat

Internal and external factors will influence the ship’s ability to maneuver. Therefore, proper planning and calculations are needed to produce good ship comfort and performance in designing a vessel. One of them is paying attention to the quality of the movement, which is the ship’s response to the influence of the sea, such as waves and wakes which are the comparison between the planned speed and the fluid flow velocity on the propeller under water. In an effort to improve the quality of good motion, this study tries to add variations in geometry and position on the foil-shaped center bulb to see the effect of vertical motion and wake. This study solves the existing problems by analyzing them using CFD software. Based on the results of the numerical simulation. In three different ship speed conditions, it has the best response when the wave heading is 0° on the ship with the addition of a center bulb in the midship area. It can reduce the vertical motion value up to 9.35% against the vessel without a center bulb and by 8.73% at 180° wave heading. So that the shape and placement of the foil-shaped center bulb on the catamaran can improve the quality of the ship’s maneuverability.