Fluid Flow Research Articles

Studying the effect of various types of chemical reactions on hydrodynamic properties of dispersion and peristaltic flow of couple-stress fluid: Comprehensive examination

A mathematical model has been constructed to examine the creeping sinusoidal flowing and diffusion of a solute material of an incompressible couple-stress fluid across a porous medium with wall features in the existence of heterogeneous-homogeneous chemical reaction. The mean effective diffusion factor is calculated using the long wavelength hypothesis, Taylor’s limit criteria, and dynamic periphery restrictions. The graphs have been used to study the effects of important constraints on the mean effective diffusion coefficient. The mean effective diffusion factor is found to rise with wall characteristics and amplitude ratio, indicating that peristalsis causes an increase in scattering. Additionally, scattering increased with the permeability constraint but decreased with the couple-stress constraint, homogeneous reaction rates, and heterogeneous reaction rates.

Online Flow Measurement of Liquid Metal Solutions Based on Impact Force Sequences: Modeling Analysis, Simulation, and Validation of Experimental Results

Aiming at the existing high-temperature liquid metal flow online accurate measurement by the metal melt characteristics, installation space, and high-temperature environment adaptability limitations, this paper innovatively puts forward a soft measurement method based on the impact force generated in the fluid flow process as an observational variable series. Fluid mechanics theory and simulation software are used to analyze and verify the feasibility of the impact force as an observable variable to measure the flow rate, followed by the construction of the CNN-LSTM-CNN-Double (CLCD) flow measurement model of impact force and flow rate based on the parameters of the learning rate and the number of training times, and finally the construction of a test platform for the flow measurement, and the validity of the method is verified through actual operation.

Heat transfer and fluid flow analysis of PCM-based thermal energy storage concept for double pass solar air heater

Solar air heaters (SAHs) are flat plate collectors used for drying applications without causing any negative impact to the environment. However, SAH suffers from two drawbacks: first is the low convective heat transfer due to formation of boundary layer along the absorber plate, and second is the low thermal efficiency resulting from the lack of solar energy available after sunshine hours. The present study aims to examine the heat transfer and friction factor characteristics of double-pass SAH using two composite roughness geometries: perforated baffles and semicylindrical PCM tubes. The study is conducted at design parameters: blockage ratio (eb/Hd) of 0.4 to 0.8 and tube radius ratios (rt/Hd) of 0.2 to 0.5 under different Reynolds numbers (Re) from 3000 to 13,000. The maximum Nusselt number (Nu) and friction factor (f) are determined to be 200 at Re of 13,000 and 0.629 at Re of 3000, respectively, for the constant value of rt/Hd as 0.3 and eb/Hd as 0.8. In the range of parameters analyzed, maximum increase in Nu and f is determined to be 5.08 times and 65.80 times, respectively, over the smooth duct. Furthermore, correlations are derived for Nu and f with mean absolute error of 4.7% and 3.8%, respectively.

A spectral collocation scheme for the flow of a piezo-viscous fluid in ducts with slip conditions

A spectral collocation scheme for the flow of a piezo-viscous fluid in ducts with slip conditions

Experimental evaluation of localized air temperature profile and performance of serpentine copper tube heat exchanger for energy-saving crop cultivation

The objective of this study is to examine the localized air temperature profile and heat transfer performance of a serpentine copper tube heat exchanger. Particularly, the air temperature nearby the plants is controlled by the heat exchanger. The novelty of this study is to provide localized climate control only near the plants targeting periodic air temperature control with the proposed heat exchanger. This study focuses on heating and cooling for cultivation in temperate and tropical regions. In contrast to fin-and-tube heat exchangers, the serpentine heat exchanger has a simple design, provides minimal shade for plants, and is easy to maintain. This study was conducted in a laboratory. The experimental system was constructed under with the assumption that a part of actual plant cultivation was being left out. The experiments were implemented by varying the experimental operating conditions such as the inlet fluid temperature and fluid flow rate in the heat exchanger. The pressure drop in the heat exchanger was also measured. The results revealed that this heat exchanger could provide localized air temperature control. The maximum air temperature difference can be obtained at approximately 12 °C during cooling and heating from their initial air temperature even though the heat exchange is simple. The effects of decreasing the inlet fluid temperature for cooling and increasing the inlet fluid temperature for heating were more dominant than the effect of the flow rate. This simple, low-maintenance, and low-cost serpentine copper tube heat exchanger can effectively provide alternate heating and cooling for plant cultivation.

The effects of drag models and operating condition on the simulation of photocatalytic degradation of pesticides in a fluidized bed reactor.

Fluidized bed reactor can enhance mass transfer and increase reaction rate. Numerical simulation helps to optimize fluidized bed reactors. The present paper models the photocatalytic oxidation of 2,4-dichlorophenoxy acetic acid in a fluidized bed reactor using the Eulerian-Eulerian model. The drag models have influences on the distribution of catalysts particles. The bed expands under the fluid flow and reaches a quasi-steady height at approximately 3s. The asymmetric distribution of catalysts with respect to the axis plane is predicted. The Gidaspow model predicts the nearly same bed expansion with the experimental data, whereas the Syamlal-O Brien model overestimates it. The simulation results at two pH values are in accordance with the experimental data. The removal in the continuous stirred tank reactor decreases with the increase in flow rate.

Gravity-driven thin film flow of a third-grade fluid on a movable inclined plane with slip boundary condition

The prime aim and essence of this study are to present a closed-form solution of the unidirectional velocity field for thin film flow generated by a third-grade liquid moving over a fixed or movable inclined plane in the presence of partial slip boundary condition. Consideration of partial slip makes this problem different from other published research works. Here lies the novelty of this study. The nondimensional, unidirectional velocity profiles rely on the material parameter of third-grade fluid, slip parameter and initial velocity of the movable plane. Study discloses that the fluid’s velocity decelerates with raising the material property of grade-3 fluid and it accelerates with the slip parameter and initial velocity of the inclined plane. The outcomes of this study are deliberated physically at length.

A universal AC electrokinetics-based strategy toward surface antifouling of underwater optics

The practical applications of underwater optical devices, such as cameras or sensors, often suffer from widespread surface biofouling. Current antifouling techniques are primarily hindered by low efficiency, poor compatibility, as well as environmental pollution issues. This paper presents a transparent electrode coating as antifouling system of underwater optics as potential substitute for alternating current electrokinetic (ACEK)-based systems. A strong-coupling model is established to predict the Joule heating induced fluid flows and the negative dielectrophoretic (nDEP) effect for mobilizing organisms or deposited sediments on optic surfaces. The performance of the proposed antifouling system is numerically evaluated through simulations of electrostatic, fluid and temperature fields as well as trajectories of submicron particles, which is then experimentally verified and found to be in good agreement. A parametric study revealed that the degree of electrodes asymmetry is the key factor affecting the flow pattern and therefore the overall performance of the system. This ACEK-based universal strategy is expected to shed light on designing high performance and non-toxic platforms toward energy-efficient surface antifouling applications of underwater optics.

Investigation of the size and shape of nano-microcarriers for targeted drug delivery to atherosclerotic plaque in ischemic stroke prevention

Recognizing the significance of drug carriers in the treatment of atherosclerotic plaque is crucial in light of the worldwide repercussions of ischemic stroke. Conservative methodologies, specifically targeted drug delivery, present encouraging substitutes that mitigate the hazards linked to invasive procedures. With the intention of illuminating their considerable significance and prospective benefits, this study examines the impact of the geometry and dimensions of drug-loaded nano-microcarriers on atherosclerotic plaque. The research utilizes a finite element approach to simulate the motion and fluid dynamics of nano-microcarriers loaded with drugs within the carotid arteries. Carriers are available in a variety of shapes and sizes to accommodate patient-specific geometries, pulsatile fluid flow, and non-Newtonian blood properties. Optimization of drug delivery is achieved through the examination of carrier interaction with the inner wall. The results demonstrated that the interaction data between particles and the inner wall of atherosclerotic plaques exhibits micro- and nanoscale patterns that are distinct. Symmetric plaques demonstrate that nanoparticles with a 0.4 shape factor and diameters below 200 nm show the highest interaction rate. Conversely, larger particles (200 and 500 nm) with shape factors of 1 demonstrate comparatively elevated interaction rates. The optimal shape factor for drug-loaded microparticles has been determined to be one, and the number of interactions increases as the diameter of the nanoparticles increases, with a significant increase observed at a shape factor of one. Asymmetric plaques exhibit the maximum interaction rates among particles that have a shape factor of 0.4 and have diameters smaller than 500 µm. The findings establish a foundation for novel therapeutic strategies, establishing nano-microparticles as auspicious contenders for accurate and efficacious drug delivery systems that inhibit plaque proliferation.

Обґрунтування вибору типу приводу стрічкового конвеєра

The designs and dynamic properties of electromechanical and hydraulic drives for a belt conveyor have been analyzed to justify their selection. The main advantages and disadvantages of their operation have been formulated. It has been established that the hydraulic drive has advantages compared to the electromechanical one for installation in a built-in drive for a belt conveyor. The design features and principles of operation of these drives have been described. Calculation schemes have been developed for the electromechanical and hydraulic drives of the belt conveyor. A mathematical model of the electromechanical drive has been constructed, taking into account the Voigt viscoelastic model for the conveyor belt, Hooke's laws for the deformation of stretching elements, equations of motion of the mechanical system, and electromagnetic phenomena in the asynchronous motor. Additionally, a mathematical model for the hydraulic drive of the belt conveyor has been constructed, which, besides the equations of motion of the mechanical system and the Voigt viscoelastic model for the conveyor belt, also includes the continuity equations of the working fluid flows in the hydraulic drive. The parameters of the belt conveyor for studying the dynamic properties of the electromechanical and hydraulic drives, which are considered in the mathematical models, have been described. The mathematical models for the electromechanical and hydraulic drives have been solved using the Mathcad software package. Theoretical curves for cases of transient processes in the mechanical system of the belt conveyor without load and with load have been constructed. Transient processes of acting torques and angular velocities have been compared by the dynamic coefficient, and it has been established that the hydraulic drive has a better indicator by 1.78 times. It has also been established that the duration of the transient process in the drive with the electric motor exceeds this parameter in the drive with the hydraulic motor by 3.5 times. It is recommended to use the built-in hydraulic drive for belt conveyors of mobile working machines because it has more advantages over the electromechanical one, and the dynamic indicators of the hydraulic drive provide better performance during operation.

Experimental and CFD analysis of fluid flow through nanofiber filter media

This work presents a novel approach to investigating the slip effect in nanofiber filter media. Electrospun nanofiber media with high efficiency and low pressure drop were produced at different concentrations and durations. The surface and cross-sectional morphology of nanofiber media were studied using FE-SEM. Fiber orientation and diameter distributions were also examined. The 3D virtual nanofiber media was modeled using this information along with the experimentally measured porosity and thickness of the media. The effect of the slip phenomenon in nanofiber media was studied numerically, and the results were compared to experimental data. Excellent agreements were found between the measured and simulation results. Additionally, filtration simulations considering aerosols injected with airflow through the nanofibrous filter media were conducted by considering the slip effect, and the effect of filter structure on filtration performance (removal efficiency and pressure drop) was investigated.

Dynamics and sorting of run-and-tumble particles in fluid flows with transport barriers

We investigate the dynamics of individual run-and-tumble particles in a convective flow which is a prototype of fluid flows with transport barriers. We consider the most prevalent case of swimmers denser than the background fluid. As a result of gravity and the effects of the carrying flow, in the absence of swimming the particles either sediment or remain in a convective cell. When run-and-tumble also takes place, the particles may move to upper convective cells. We derive analytically the probability of uprise. Since that probability in a given fluid flow can vary strongly across species, our findings inspire a purely dynamical mechanism for species extraction in the dilute regime. Numerical simulations support our analytical predictions and demonstrate that a judicious choice of the fluid flow’s parameters can lead to particle sorting with an arbitrary degree of purity.

Impact of chemical reaction on the Cattaneo–Christov heat flux model for viscoelastic flow over an exponentially stretching sheet

In this article, the numerical solutions for the heat transfer flow of an upper-convected Maxwell fluid across an exponentially stretched sheet with a chemical reaction on the Cattaneo–Christov heat flux model have been investigated. Using similarity transformation, the controlling system of nonlinear partial differential equations was transformed into a system of ordinary differential equations. The resulting converted equations were solved numerically by a successive linearization method with the help of MATLAB software. A graphic representation was created to analyze the physical insights of the relevant flow characteristics. The findings were presented in the form of velocity, temperature, and concentration profiles. As the relaxation time parameter varied, the local Nusselt number increased. The thermal relaxation time was shown to have an inverse relationship with fluid temperature. Furthermore, the concentration boundary layer becomes thinner as the levels of the reaction rate parameter increase. The results of this model can be applicable in biological fluids and industrial situations. Excellent agreement exists between the analysis's findings and those of the previous studies.

Fractional modeling of unsteady flow of Jeffrey fluid using active and passive control strategies

The current work is focused on the analysis of heat and mass transfer in a magnetohydrodynamics Jeffrey nanofluid flows across a vertical plate because of these possible uses. Free convection, magnetic effect, and thermo-diffusion properties are all applied to the flow considered here. The modeling also takes into account the passive and active control of the Jeffrey nanofluid. The constant proportional Caputo fractional operator which was recently introduced is used in this work together with generalized Fick’s and Fourier’s law. Using suitable nondimensional variables, ordinary differential equations are obtained from the modeling equations, and the Laplace transform method is used to solve these modeled equations. The concentration and temperature profiles are rising functions of the fractional and thermophoresis parameters, and they drop more quickly as the values of the Schmidt, Prandtl, and Nb (Brownian motion parameters) rise. The constant proportional Caputo (CPC) fractional derivative is the best choice for achieving more stable concentration, temperature, and velocity than conventional fields. Raising the values of α will increase the rate of heat transfer and skin friction coefficient. Additionally, as compared to the classical model, the constant proportional Caputo derivative model shows more decay nature. Consequently, compared to the classical model, the constant proportional Caputo differential model has a superior memory function.

Fractal dimension and its implication to Mineral Exploration: A case study from Jonnagiri and Gadag gold deposits in India

Fractal dimensions characterise the spatial distribution pattern of mineral deposits, allowing the mineralization processes to be grasped beneath and at the surface. This study considered the mineralized vein along the fracture/shear zone near Dona temple, Jonnagiri gold deposit and borehole data from Sangli block, Gadag gold deposit. The above mentioned zones are considered using fractal dimensional analysis to constrain the fluid flow pathways. The box-counting technique is used to measure the fractal dimension of the mineralized vein along the surface from a detailed to regional scale. The fractal correlation integral method is used to provide the fractal dimension values from the gold assay (in g/t). The obtained box-counting fractal dimension values vary from 1.07 to 1.36, whilst fractal dimensions obtained from the fractal correlation integral method range from 0.03 to 1.97. Higher fractal values signify a fully matured interlinked fracture/fault network with steep fluid flow pathways, while lower values indicate the converse condition. Further, the study shows that the fractal analysis of the mineralized vein along fracture/shear zone appears to correlate with the fault system rather than the litho-contact. Economic gold deposition is mainly along the structure with steep fractal gradient, which is the target area for economic gold exploration.

Numerical analysis of heat transfer and fluid flow structures of jet impingement on a flat plate with different shapes of roughness elements

Jet impingement is a heat transfer technique utilized in different applications in industry. It is used for cooling the turbine blade and the combustor wall because of its high cooling rate. The heat transfer (HT) and flow structure of a circular air-impinging jet over a flat target plate with a circular row of 48 roughness elements are numerically investigated using renormalization group k–ε turbulence model. Different shapes of roughness elements, namely cylindrical roughness elements (CREs), droplet roughness elements (DREs), and hemispherical roughness elements (HREs), are examined. The effects of Reynolds number changed from 7,000 to 35,000, and the roughness elements location relative to jet diameter ( s / d ) of 1.5, 2, 2.5, and 3 at a constant jet-to-target plate distance ( H / d ) of 2 are studied. Temperature distribution, local Nusselt number ( Nu ), average Nusselt number (Nuavg ), average Nusselt number ratio (Nuavg,r ), velocity distribution, turbulence kinetic energy, streamline contours, and static pressure ( p ) over the roughness elements are evaluated and discussed. The results showed that the existence of roughness elements has a significant effect on the thermal and hydraulic characteristics. The Nuavg,r for the CREs, DREs, and HREs is up to 1.61, 2.02, and 1.2, respectively. All roughness element shapes increase the flow velocity in the narrow area between the elements and increase the wetted area. CREs augment the HT rates by increasing the turbulence intensity, while DREs reduce the drag force effects.

On Error Estimates of a discontinuous Galerkin Method of the Boussinesq System of Equations

Abstract In this paper, we propose and analyze a discontinuous Galerkin finite element method for solving the transient Boussinesq incompressible heat conducting fluid flow equations. This method utilizes an upwind approach to handle the nonlinear convective terms effectively. We discuss new a priori bounds for the semidiscrete discontinuous Galerkin approximations. Furthermore, we establish optimal a priori error estimates for the semidiscrete discontinuous Galerkin velocity approximation in L 2 \mathbf{L}^{2} and energy norms, the temperature approximation in L 2 L^{2} and energy norms and pressure approximation in L 2 L^{2} -norm for t > 0 t>0 . Additionally, under the smallness assumption on the data, we prove uniform in time error estimates. We also consider a backward Euler scheme for full discretization and derive fully discrete error estimates. Finally, we provide numerical examples to support the theoretical conclusions.

Flow Analysis of Central Venous Outflow Tract: A New Approach to Understanding Pulse-Synchronous Tinnitus.

Pulse-synchronous tinnitus (PST) has been linked to multiple anatomical variants of the central venous outflow tract (CVOT) including sigmoid sinus (SS) dehiscence and diverticulum. This study investigates flow turbulence, pressure, and wall shear stress along the CVOT and proposes a mechanism that results in SS dehiscence and PST. Case series. Tertiary Academic Center. Venous models were reconstructed from computed tomography scans of 3 patients with unilateral PST. Two models for each patient are obtained: a symptomatic and contralateral asymptomatic side. A turbulent model-enabled commercial flow solver was used to simulate the pulsatile blood flow over the cardiac cycle through the models. Fluid flow through the transverse and SS junction was analyzed to observe the velocity, pressure, turbulent kinetic energy (TKE), and shear stress over a simulated cardiac cycle. Fluid flow on the symptomatic side showed increased vorticity in the presence of an SS diverticulum. Higher TKE with periodicity following the cardiac cycle was observed on the symptomatic side, and a sharp increase was observed if SS diverticulum was present. Shear stress was highest near the narrowest segments of the vessel. Pressure was observed to be lower on the symptomatic side at the transverse-SS junction for all 3 patients. Computational fluid dynamics modeling of blood flow through the CVOT in PST suggests that low pressure may be the cause of dehiscence, and tinnitus may result from periodic increases in TKE.

Flow Analysis of Central Venous Outflow Tract: A New Approach to Understanding Pulse-Synchronous Tinnitus.

Pulse-synchronous tinnitus (PST) has been linked to multiple anatomical variants of the central venous outflow tract (CVOT) including sigmoid sinus (SS) dehiscence and diverticulum. This study investigates flow turbulence, pressure, and wall shear stress along the CVOT and proposes a mechanism that results in SS dehiscence and PST. Case series. Tertiary Academic Center. Venous models were reconstructed from computed tomography scans of 3 patients with unilateral PST. Two models for each patient are obtained: a symptomatic and contralateral asymptomatic side. A turbulent model-enabled commercial flow solver was used to simulate the pulsatile blood flow over the cardiac cycle through the models. Fluid flow through the transverse and SS junction was analyzed to observe the velocity, pressure, turbulent kinetic energy (TKE), and shear stress over a simulated cardiac cycle. Fluid flow on the symptomatic side showed increased vorticity in the presence of an SS diverticulum. Higher TKE with periodicity following the cardiac cycle was observed on the symptomatic side, and a sharp increase was observed if SS diverticulum was present. Shear stress was highest near the narrowest segments of the vessel. Pressure was observed to be lower on the symptomatic side at the transverse-SS junction for all 3 patients. Computational fluid dynamics modeling of blood flow through the CVOT in PST suggests that low pressure may be the cause of dehiscence, and tinnitus may result from periodic increases in TKE.

Numerical analysis of the axisymmetric lattice Boltzmann method for steady and oscillatory flows in periodic geometries

Compared to more typical computational fluid dynamics techniques, the lattice Boltzmann method (LBM) is relatively new and unexplored. In recent years, axisymmetric LBM formulations, which can simulate flow in rotationally symmetric 3D geometries, have been published. Here we verify a novel axisymmetric LBM implementation using numerical criteria. Hagen–Poiseuille and Womersley flow are considered within a straight tube where analytic solutions are available. With this, we establish sufficient accuracy of the approximated flow and study the effects of changing simulation parameters (e.g. Reynolds number, Womersley number) and spatial/temporal parameters (e.g. relaxation time, mesh nodes, time steps). Furthermore, steady and oscillatory flows within a periodically-varying, longitudinally asymmetric geometry are considered. Analytic solutions are not available in these cases; however, the validity of the axisymmetric LBM for curved boundaries is ensured through convergence, mesh independence and qualitative observations. Guaranteeing reasonable flow field determination for the aformentioned geometry is relevant to a larger problem where particulate suspension is pumped back and forth through a membrane of axisymmetric micropores. In these circumstances, experiments have induced directed particle transport even though there is no net flow of the carrier fluid. Hence, our work aims to improve current numerical simulations of these flow problems to better understand the factors that facilitate particle transport.