Increase In Flow Resistance Research Articles

Modeling and simulation of osteocyte process–fluid interaction in a canaliculus

An osteocyte is a bone cell situated inside a hard bone matrix in an interstice (lacuna). It has many dendritic structures called cellular processes that radiate outward from the cell through the bone matrix via cylindrical openings (canaliculi). Osteocytes can sense stress and strain applied by the interstitial fluid flow and respond by releasing biochemical signals that regulate bone remodeling. In vitro experiments have suggested that the stress and strain typically experienced at the macroscale tissue level have to be amplified 10× in order for osteocytes to have a significant response in vivo. This stress and strain amplification mechanism is not yet well understood. Previous studies suggest that the processes are the primary sites for mechanosensation thanks to the tethering elements that attach the process membrane to the canalicular wall. However, there are other potential factors which may also contribute to stress and strain amplification, such as canalicular wall geometry and osteocyte-associated proteins in the interstitial space called pericellular matrix. In this work, we perform computational studies to study how canalicular wall roughness affects stress and strain amplification. Our major finding is that the wall roughness induces significantly greater wall shear stress (WSS) on the process when the wall roughness increases flow resistance; and the roughness has relatively smaller influence on the WSS when the resistance remains the same.

Influence of ultrasonic vibration on forming force of 1060 aluminum sheet single point incremental forming

A device combining ultrasonic vibration plastic processing technology and single point incremental forming was developed in this work, with maximum power output of 2 kW at frequency of 20 kHz. On this basis, together with theoretical study, experiments and finite element simulation on forming force with aluminum alloy sheet 1060, the results showed that the forming force reduced evidently by appropriate selection of amplitude and frequency, meanwhile, the change of them had a remarkable influence on plastic behavior which can be summarized into two opposite aspects: the softening and the hardening effect. When a lower amplitude and frequency was applied to the forming process, the softening effect dominated, leading to a decrease of forming force, however, under the application of a high-vibrating amplitude and frequency, the harden effect dominated resulting in the decline of plasticity and the increase of flow resistance. The theoretical analytical results and the finite element simulation results are in good agreement with the experimental results, which verified the accuracy of the theoretical model and simulation model. The research results provide theoretical and technical basis for selecting vibration parameters of ultrasonic vibration single point incremental forming.

Biomimetic porous wick with efficient fluid transport and excellent heat transfer for loop heat pipes

The porous wick, as a core component of the loop heat pipe (LHP), serves as a source of circulation power. Inspired by the transport system of plant vessels, a radially stacked polyethersulfone (PES) porous wick was designed using PES membranes with an anisotropic porous structure. The PES membranes exhibited excellent capillary force and high permeability. However, the supply capacity of the axially stacked wick was far inferior to that of sintered wick due to the problem of contact gaps and pore misalignment between layers. From the bionic point of view, a laminar winding special transport structure, which is perpendicular to the direction of liquid transport was proposed. The method effectively avoids the adverse effects of gap and pore misalignment on liquid transport. Combining experimental and simulation methods, the heat transfer characteristics and liquid transport characteristics of the radial stacking polyethersulfone wick (RPES) were studied and compared with those of traditional axial stacking polyethersulfone wick (APES) and sintered nickel wick. The results showed that the heat transfer performance of RPES-LHP was significantly improved, with the heating surface temperature maintained at 54.1 °C and thermal resistance of 0.095 °C/W under a heat load of 400 W, which was respectively 26.6 °C and 0.066 °C/W lower than that of the APES-LHP. The evaporator thermal resistance of RPES-LHP also ranked among the top in existing research on wicks. Simulation results indicated that the radial stacking method avoided capillary force weakening and flow resistance increase caused by gap and pore misalignment, thereby enhancing the supply capacity of RPES. The concept of regulating the stacking orientation of the wick to be perpendicular to the direction of liquid transport can strengthen the supply capacity and provide light on the design of porous wicks in the future.

Flow resistance enhancement for the leakage decrease of labyrinth seals using teeth tip winglets

A novel flow resistance enhancement technology is proposed to decrease the leakage flow for labyrinth seals adopting teeth tip winglets (TTW). The specially designed TTW is utilized to double the throttling effect at each teeth tip. In addition, the annular slots on the TTW can also generate teeth tip vertexes. These vertexes disrupt the direction of teeth tip leakage flow, enhancing the local flow resistance. To validate this concept, a three-dimension computational fluid dynamic model (CFD) is established. The flow field and leakage performance of the seal with TTWs are calculated with compassion to the baseline seal. Results show that the TTW seals increase flow resistance at the teeth tips, resulting in an extra dissipation effect. As a result, the maximum leakage decrease ratio reaches up to 15.1%

The Mechanism Study of Fracture Porosity in High-Water-Cut Reservoirs

Many onshore oil fields currently adopt water flooding as a means to supplement reservoir energy. However, due to reservoir heterogeneity, significant differences in permeability exist not only between different reservoirs but also within the same reservoir across different planar orientations. After prolonged fluid flushing in the near-wellbore zone of injection wells, the resulting increased flow resistance between layers exacerbates inefficient and ineffective circulation. A considerable amount of remaining oil is left unexploited in untouched areas, significantly impacting the overall recovery. To investigate the multiscale plugging mechanisms of fracture-dominated pore channels in high-water-cut oil reservoirs and achieve efficient management of fractured large channels, this study explores the formation of the fracture-flushing zone-low saturation oil zone. A physical experimental model with fractures and high-intensity flushing is established to analyze changes in pore structure, mineral composition, residual oil distribution, and other characteristics at different positions near the fractures. The research aims to clarify the mechanism behind the formation of large channels with fracture structures. The results indicate that under high-intensity water flushing, cementing materials are washed away by the flowing water, clay particles are carried to the surface with the injected fluid, and permeability significantly increases, forming high-permeability zones with fracture structures. In the rock interior away from the fracture end, channels, corners, and clustered oil content noticeably decrease, while the content of film-like oil substantially increases, and clay minerals are not significantly washed away. Under strong flushing conditions, the number of residual clay particles near the fracture end is mainly influenced by flow velocity and flushing time; thus, the greater the flushing intensity, the faster the water flow, and the longer the flushing time, the fewer residual clay particles near the fracture end.

Convective transport in a nanofluid-filled annulus with an eccentric hypocycloid within a square disk

Considering varying cusp numbers, we investigate the time-dependent, incompressible natural convective flow of an iron oxide-water nanofluid within an annulus formed between a square and a concentric hypocycloid. The vertical walls of the annulus are treated as relatively colder walls, while the bottom wall of the square disk and the inner hypocycloid wall act as heat sources. The outer upper wall of the square is considered adiabatic. We transform the dimensional, nonlinear, and strongly coupled fundamental equations of nanofluids in Cartesian coordinates into non-dimensional equations. We utilize the Galerkin finite element method to solve the governing equations. This study comprehensively explores the flow and heat transfer of nanofluids, considering the essential parameters relevant to the problem. The results highlight a remarkable observation, as the ferric oxide-water nanofluid exhibits significantly enhanced heat transfer compared to the conventional fluid. The precise positioning of the hypocycloid in the cusp configuration represents a critical phenomenon that substantially improves the flow and heat transfer rates of the nanofluid. The three cusped hypocycloids positioned on the inner wall of the annulus perpendicular to the horizontal axis result in a nanofluid flow configuration and heat transfer that surpasses other configurations and cusp numbers studied in the analysis. Notably, heat transfer exhibits a discernible increase with an increase in the nanoparticle volume fraction (maximum 3vol%), while it declines with an increase in the nanoparticle diameter. The intricate relationship between the nanoparticle diameter, volume fraction, cusp number, and hypocycloid configuration substantially influences the friction factor and particle-surface interactions. As the number of cusps on the inner surface increases, the velocity magnitude, Nusselt number, and concentration profiles near the boundary layer decrease, while the fluctuations of the middle annulus indicate the combined influence of nanoparticle dispersion and the formation of the annulus boundary layer due to the orientation of hypocycloidal cusps. Furthermore, an increase in the particle diameter and the sharpness of the corners of the hypocycloid lead to a proportional increase in the nanofluid flow resistance within the annulus.

Dune Development Dominates Flow Resistance Increase in a Large Dammed River

AbstractDunes are important for bedload transport in almost all large river systems and exert an important control flow resistance. Investigating dunes is fundamental for simulating discharge, sediment transport, and flood routing. However, the spatiotemporal dynamics of dunes and flow resistance remain poorly understood in large alluvial river systems mainly due to the lack of high‐resolution data. Here we analyzed in‐field observed data on annual profiles of 450 cross‐sections, river bathymetry, discharge, water levels, and sediment in the Middle Yangtze River, and found that dunes developed and flow resistance increased (+10%) in the post‐Three Gorges Dam period. We ascertain that the development of dunes plays the dominant role in augmenting flow resistance, as evidenced by roughness height change (+29%) using a modified Van Rijn method. Ultimately, dune development was incorporated into a hydrogeomorphic numerical model of the Yangtze River to improve flow resistance quantification, and thus, the water level simulation. Our findings highlight the potential increase in flow resistance in response to upstream damming in large rivers and have important implications for flood management and riverine ecology.

MHD nanofluid flow between porous convergent-divergent channel with velocity slip and nanoparticle aggregation

The aggregation of nanoparticles is a major phenomenon having broad consequences in many fields. In order to fully utilize the capabilities of nanoparticles in a variety of applications and to evaluate the effects that they will have on the environment and biological systems, it is crucial to comprehend and manage aggregation. To develop and improve nanoparticle-based technology, researchers are still learning more about the aggregation processes. Thus, the present study investigates the combined effects of velocity slip and nanoparticle aggregation on Heat transfer (HT) analysis of MHD nanofluid (i.e., TiO2-C2H6O2) flow between porous convergent, divergent channel. The modified Krieger–Dougarty and Maxwell–Bruggeman models were utilized for nanoparticle aggregation. The modeling is based on nonlinear PDEs such as continuity, momentum, and heat equations. These equations are transformed into a system of nonlinear ODEs using similarity transformations and then solved numerically and analytically. The analytical solution has been constructed using the ADM method. The present results in particular cases are compared to results obtained by the HAM- package and by the Runge- Kutta Fehlberg 4th–5th order (RKF-45) for validation. The effects of active parameters on the velocity, temperature, concentration, skin friction, and Nusselt numbers are investigated. It is found that nanoparticle aggregation can limit fluid velocity in converging channels by increasing flow resistance through aggregate formation. Individual nanoparticles generate friction and lower velocity, while aggregated nanoparticles boost fluid density and velocity. In addition, it is found that the magnetic field lowers skin friction and increases HT due to Lorentz force, while porosity increases friction and HT. Nanoparticle concentration inversely affects friction, increasing friction without aggregation and decreasing friction with aggregation, with the HT rate rising with increased nanoparticle concentrations.

Controlling TPMS lattice deformation for enhanced convective heat transfer: A comparative study of Diamond and Gyroid structures

This study investigates the enhancement of convective heat transfer in Triply Periodic Minimal Surfaces (TPMS), focusing on Gyroid and Diamond lattice structures. An innovative lattice structure control method, employing a Deform-Control parameter (β), is proposed to modulate lattice deformation within their mathematical frameworks. Numerical simulations validated by experimental measurements were conducted to analyze the impact of varying β values from 0 to 0.75 on the thermo-hydraulic performance of both lattice types at flow rates ranging from 0.4 m3/h to 2 m3/h. The results indicate significant improvements in heat transfer efficiency with increasing β. For Gyroid structures, increasing β from 0.1 to 0.75 led to a 3.8% to 32.7% rise in convective heat transfer coefficients and a 3.2% to 23.7% increase in Nusselt numbers. Diamond structures also demonstrated enhancements, with coefficients and Nusselt numbers climbing by 2.9% to 10.4% and 3% to 7%, respectively. Notably, both Gyroid and Diamond structures showed increase in flow resistance at higher β values, highlighting a critical balance between heat transfer efficiency and fluid flow considerations. This research presents a promising control method for optimizing heat transfer in TPMS structures, offering opportunities for more efficient and effective heat dissipation solutions.

Effect of curvature ratio on curved microchannel heat sinks

This work studies the influence of curvature ratio on flow and heat transfer in curved microchannel heat sinks, and introduces an innovative thermal test method that can be integrated into the micro heat sink and other micro-devices. The thermal performance was rigorously evaluated using a comprehensive set of parameters, including Reynolds number, Nusselt number, Poiseuille number. Within the scope of the study, microchannel heat sink with larger curvatures exhibit superior comprehensive thermal performance, but this also leads to an increase in flow resistance within a controllable range. However, larger curvatures are also constrained by machining precision, mechanical stability, and fabrication costs.

Thermal analysis and structure optimization of wavy microchannel with combining ribs of porous layer and solid wall in multi objective genetic algorithm

The combining rib of porous layer and solid wall is set in wavy microchannel heat sink to enlarge heat transfer area and convection with smaller increase in flow resistance, in which the consumption of pump power relates to the ratios of wave amplitude to length or to width and the thickness of porous layer due to vortices generation while coolant passing through channel. The local thermal equilibrium occurs in porous layer, and the Forchheimer-Brinkman-Darcy relations were used to describe the flow inside porous ribs. The effects of channel-to-pitch width ratio, width ratio of porous layer to pitch and microchannel height on its cooling performance are investigated, and the parameter of figure of merit (FOM) is defined to evaluate thermo-hydraulic performance in wavy microchannel. Besides, the multi objective genetic algorithm method is employed to optimize structure parameters in wavy microchannel to obtain better performances, in which the increase in thermal resistance from 0.062 K/W to 0.166 K/W together with consumption of pump power decreasing from 0.00416 W to 0.00185 W can be obtained in the Pareto front set, and it relates to the heat dissipation in convection between coolant and bottom surface or vertical side ribs. Compared to wavy microchannel with solid rib, the 37.61% and 16.67% decreases respectively in thermal resistance and consumption of pump power occur in the case with optimal combining rib of porous layer and solid wall.

Engine oil blended Casson hybrid nanofluid flow along a uniformly heated curved surface with Arrhenius activation energy and suction: A computational study

The research studies the numerical analysis of an incompressible Casson hybrid nanofluid, composed of Fe3O4–Cu nanoparticles blended with engine oil, flowing over an exponentially stretched curved surface. It explores the effects of an aligned magnetic field, a uniform heat source, activation energy, and suction while maintaining a low Prandtl number. By employing appropriate similarity transformations, the original partial differential equations are converted into ordinary ones and solved using bvp4c in MATLAB. Graphs and tables depict the influence of dimensionless factors on skin friction coefficient, velocity, thermal, and concentration profiles, as well as Nusselt and Sherwood numbers. The computational findings reveal that magnetic field alignment significantly modifies velocity, decreasing it while uniformly enhancing temperature and concentration profiles. Casson fluid behavior in engine oil amplifies temperature and concentration profiles, thereby enhancing heat and mass transfer rates. Moreover, an increased heat source elevates temperature but reduces overall heat transfer. The chemical reaction parameter diminishes concentration, whereas activation energy enhances it, albeit impacting the mass transfer rate conversely. Additionally, suction increases flow resistance, while the stretching parameter exhibits an inverse effect, both positively influencing heat and mass transfer rates at higher values. Practically, these findings offer insights crucial for optimizing heat exchangers, biomedical devices, and cooling systems, enhancing their efficiency and performance. Additionally, they inform the design of industrial processes involving fluid flow, aiding in the development of more effective and sustainable solutions.

Study of flow and heat transfer performance of nanofluids in curved microchannels with different curvatures

This study focuses on investigating the flow and heat transfer characteristics of Copper-water nanofluids (Cu-H2O) and water in microchannels with varying curvatures. The results reveal that Cu-H2O nanofluids demonstrate superior heat transfer performance compared to pure water in all four microchannels. Moreover, curved microchannels exhibit higher heat transfer performance than straight microchannels, regardless of whether the flow is laminar or turbulent. The heat transfer performance improves with increasing channel curvature, volume fraction of nanoparticles, and decreasing particle size. During laminar flow, the impact of curvature on heat transfer performance is more significant. However, during turbulent flow, variations in volume fraction have a greater influence on heat transfer performance compared to changes in curvature and particle size reduction. While larger volume fractions and higher curvatures increase flow resistance, this relationship is less pronounced for turbulent flow as Reynolds number and volume fraction increase. It is worth noting that the comprehensive heat transfer performance index does not consistently improve with increasing curvature, and sometimes straight microchannels outperform curved microchannels with specific curvatures. Additionally, curved microchannels exhibit a smaller average field synergy angle (FSA) compared to straight microchannels, indicating better synergy between the flow field and temperature field. The FSA also shows a relatively uniform distribution of local field synergy angles throughout the flow region in curved microchannels. Furthermore, the FSA decreases as the curvature increases.

Unsteady solute transport in Casson fluid flow and its retention in an atherosclerotic wall

In the current study, a mathematical model of convective solute transport and its retention in an atherosclerotic wall is examined. The artery wall is supposed to be permeable and has cosine-shaped stenosis caused by various sorts of abnormal growth or plaque formation. The flowing blood is modeled as the suspension of all red blood cells in plasma, thought to be Casson fluid. The Immersed Boundary Method (IBM) and the Marker and Cell (MAC) method are used to numerically solve the unsteady governing equations of motion along with the appropriate initial and boundary conditions. The final results of the quantitative studies contain the corresponding flow-field and solute distribution profiles for the full arterial length. The essential components are evaluated, including the wall shear stress, wall concentration, and concentration contours. According to simulation data, the permeability of the wall directly affects the solute transport within the therapeutic region. The yield stress does, however, increase flow resistance and decrease solute uptake within the tissue. The projected outcomes are remarkably in line with previously published findings, which supports the applicability of the model under investigation.

Study on cross-section distortion behaviors for tube bending at varying geometry parameters

Tube bending is often plagued by the critical forming defect of cross-section distortion, which increases flow resistance, affects the strength and stiffness of bent-tube, and thus directly influences the usage performance of bent-tube components. To achieve accurate tube bending forming, the distortion behaviors for cross-section during tube bending should be clarified. A finite element (FE) model accounting for the change in elastic modulus was employed for addressing the distortion behaviors of the cross-section for high strength 0Cr21Ni6Mn9N (0Cr21Ni6Mn9N-HS) tube in NC rotary draw bending at varying geometry parameters. The findings indicate that accounting for the change in elastic modulus can aggrandize the distortion ratio of the cross-section, but has no significant impact on the distortion behaviors for the cross-section. The cross-section ovality behaviors of the 0Cr21Ni6Mn9N-HS tube at various geometry parameters for NC rotary draw bending have been clarified, and the ranges of sound parameters have been determined.

Influence of fin length and width on flow and heat transfer performance of miniature heat sinks

Miniature heat sinks are employed in electronic cooling applications owing to greater heat transfer characteristics and better surface-to-volume ratio. Pin fins are typically used to further enhance the thermal-hydraulic performance of such heat sinks. The present numerical investigation analyses the effect of both relative height (Hr = h/hc) as well as relative width (Wr = w/wc) of pinfin for the channel having a rectangular cross-section of 1.5 mm and 1 mm in width (wc) and height (hc) respectively while keeping the flow laminar. Five models having different Hr (0.2 to 1.0) and five models having different Wr(0.066 to 0.333) are investigated and the results are compared with the rectangular channel without fin. Findings indicate significant enhancement of thermal-hydraulic performance with increasing fin relative height as well as relative width which tends to increase flow resistance. Relative height on fins improves the Nusselt number by 11.40 %–84.81 %, while relative width increases it by 14.92 %–94.32 % for the examined range of Reynolds numbers. The microchannel that has the highest value of thermal performance factor (1.46) in the model has Hr = 0.8 and Wr = 0.333.

The Fluid–Solid Interaction in the Nonlinear Pressure–Flux Relationship of Bordered Pits in Oriental Arborvitae (Platycladus orientalis)

The nonlinear pressure–flux relationship in the xylem of a conifer is attributed to the fluid–solid interaction within the bordered pits. However, the fluid–solid interactions between the torus–margo structure and the water flow within the pit lack comprehensive understanding. Herein, a fluid–solid interaction model was developed including the deformation of the torus–margo and the flow of water transportation. Nine pit samples were reconstructed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) pictures. Fluid–solid coupling models for pits in the stems of oriental arborvitae (Platycladus orientalis) were developed. The deflection of the torus was roughly proportional to the pressure difference between adjacent tracheids, while the pit resistance exhibited a considerable nonlinear increase. From 250 to 1750 Pa, the pit resistance increased from 4.1466 × 1016 Pa·s/m3 to 8.8344 × 1016 Pa·s/m3. The pit resistance decreased, and the pit’s ability to regulate water flow enhanced when the pit diameter increased. Both the pit resistance and the pit’s ability to regulate water decreased when the pit depth increased. The decrease in Young’s modulus for the margo promoted the nonlinear pressure–flux relationship in bordered pits. The findings provide theoretical evidence for the nonlinear relationship between pressure and flux in bordered pits, as well as for the prevention of gas bubble transit through a bordered pit during tracheid cavitation. The passive hydraulic regulation of bordered pits could increase flow resistance and reduce the water flow rate in the xylem, inhibiting tree transpiration.

In-situ emulsification in low-tension surfactant/polymer systems: Impacts on enhanced oil recovery

The flow of two immiscible liquids in porous media can lead to fluid mixing, resulting in emulsions—where one phase is dispersed as droplets in the other. In reservoir rocks, natural surfactants and polar molecules, like asphaltenes, can promote oil–water emulsion formation. During chemically enhanced oil recovery processes (CEOR) such as surfactant, alkali, or surfactant-alkali flooding, in-situ emulsification is often seen as key to enhancing frontal stability and facilitating the piston-like displacement of oil by water. However, this work reports a minimal effect of in-situ emulsification on oil production during surfactant-polymer (SP) flooding. Experimental studies show this by injecting prepared emulsions into a multi pressure-tap core holder and examining emulsion formation in one reservoir core before moving it into a second core for oil displacement. This helps us understand the specific role of emulsions in oil mobilization. Factors like surfactant concentration, interfacial tension, and the timing of introducing the surfactant-polymer solution do influence the intensity of in-situ emulsification. Yet, the incremental oil recoveries show no significant differences. Through similar experiments, it is observed that ultra-low interfacial tension (IFT) in our surfactant-polymer system is the primary mechanism for oil mobilization. The slight increase in pressures suggests that in-situ emulsification has a limited role in increasing flow resistance during the ultra-low IFT SP flood process, potentially not improving the swept volume. This research can guide the development of systematic approaches to analyze the effects of in-situ emulsification on oil mobilization and evaluate chemical flooding processes.

Optimization of a wavy-channel compact solar receiver with supercritical carbon dioxide

The compact solar receiver stands out as a promising solar absorber for the direct supercritical carbon dioxide cycle, and the wavy channel exhibits notable comprehensive performance owing to its excellent heat transfer capabilities and relatively low flow resistance. However, there exists considerable room for improvement in performance through the optimization of geometric parameters in wavy channels. In this paper, the amplitude and the period of the wavy channel are optimized by a coupled response surface method with multi-objective genetic algorithm, with objectives of maximizing the heat transfer coefficient and minimizing the friction factor. Results indicated that smaller period or larger amplitude enhances heat transfer but also increases flow resistance. Through the non-dominated sorting genetic algorithm and k-means clustering method, five representative optimal solutions were identified. The optimal result, characterized by a period of 15.07 mm and an amplitude of 1.73 mm, was selected based on the highest comprehensive heat transfer factor under identical pump power, reaching 1.213. This solution demonstrated high comprehensive performance across a wide range of working conditions. The optimization results are not only valuable for the design of compact solar receivers but also hold significant potential for application in other compact heat exchangers, such as printed circuit heat exchangers.

Thermo-hydraulic performance of tungsten flat tile type divertor target with two types of novel engineered cooling channel wall

The divertor is one of the key components in magnetic confinement fusion reactors. Improving the heat transfer performance of the divertor has great importance for promoting its service capacity. This work proposed a new kind of cooling surface configuration for a flat-type divertor design, which is based on the concept of synergetic heat transfer enhancement via combination of a sinusoidal undulation structure with a micro-nano structured surface (copper-mesh brazed coating). The combination surface configuration is preliminarily obtained by numerical optimization based on the calibrated model of subcooled flow boiling heat transfer. Then, experimental mockups were fabricated and tests with high heat flux (HHF) conditions were conducted to examine the effects of the new design. Both the numerical and experimental results confirm that the incident critical heat flux is increased from 15 MW/m2 of the micro-nano structured flat surface case to over 22 MW/m2 of the combination case under the conditions of relatively low flow velocity of 3 m/s and low flow resistance increase of 7.3 %.