Channel Cross Research Articles

PENGARUH VARIASI POSISI PEMASANGAN DAN ARAH ALIRAN FLUIDA TERHADAP KINERJA VENTURI VAKUM

A liquid fluid flow that is driven by a centrifugal pump past the ventury channel needed to produce the vacuum conditions at the ventury vacuum pump. The amount of vacuum pressure produced by ventury is influenced by the increase of flow rate due to the channel cross section that follows the Bernoulli principle. The flow rate on the channel is affected by the discharge generated by the pump that follows the law of continuity. In addition to speed, the pressure of channel input is also a variable that affects ventury vacuum pressure. Pressure losses and flow discharge caused by the connection or turn of the pipe arising from the installation design, will affect the performance of the Setrifugal pump in the form of discharge flow and pressure that ultimately strongly affects the rally Venturi vacuum work.
 Therefore, it is necessary to evaluate the influence of the design of the istalation associated with the position of ventury mounting and the direction of the flow to the pressure and discharge of the vacuum to be the primary purpose of this research so that the variables are obtained The performance of a ventury vacuum pump.
 In this research the placement of vacuum ventury in several positions, namely vertical position, horizontal position and tilt position 45o. Then measured parameters are occurring, such as discharge fluid flow, liquid fluid pressure and vacuum pressure occurring on the pipe.
 From this study obtained optimum performance on the installation with a sloping ventury position of 45o with the direction of the downward flow, which resulted in the lowest vacuum pressure of-65 CmHg with ventury suction flow of 33.01 liters/minute.

Optimal Control of Colloidal Trajectories in Inertial Microfluidics Using the Saffman Effect.

In inertial microfluidics colloidal particles in a Poiseuille flow experience the Segré-Silberberg lift force, which drives them to specific positions in the channel cross section. An external force applied along the microchannel induces a cross-streamline migration to a new equilibrium position because of the Saffman effect. We apply optimal control theory to design the time protocol of the axial control force in order to steer a single particle as precisely as possible from a channel inlet to an outlet at a chosen target position. We discuss the influence of particle radius and channel length and show that optimal steering is cheaper than using a constant control force. Using a single optimized control-force protocol, we demonstrate that even a pulse of particles spread along the channel axis can be steered to a target and that particles of different radii can be separarted most efficiently.

Effects of Tidally Varying River Flow on Entrainment of Juvenile Salmon into Sutter and Steamboat Sloughs

Survival of juvenile salmonids in the Sacramento–San Joaquin Delta (Delta) varies by migration route, and thus the proportion of fish that use each route affects overall survival through the Delta. Understanding factors that drive routing at channel junctions along the Sacramento River is therefore critical to devising management strategies that maximize survival. Here, we examine entrainment of acoustically tagged juvenile Chinook Salmon into Sutter and Steamboat sloughs from the Sacramento River. Because these sloughs divert fish away from the downstream entrances of the Delta Cross Channel and Georgiana Slough (where fish access the low-survival region of the interior Delta), management actions to increase fish entrainment into Sutter and Steamboat sloughs are being investigated to increase through-Delta survival. Previous studies suggest that fish generally “go with the flow”—as net flow into a divergence increases, the proportion of fish that enter that divergence correspondingly increases. However, complex tidal hydrodynamics at sub-daily time-scales may be decoupled from net flow. Therefore, we modeled routing of acoustic tagged juvenile salmon as a function of tidally varying hydrodynamic data, which was collected using temporary gaging stations deployed between March and May of 2014. Our results indicate that discharge, the proportion of flow that entered the slough, and the rate of change of flow were good predictors of an individual’s probability of being entrained. In addition, interactions between discharge and the proportion of flow revealed a non-linear relationship between flow and entrainment probability. We found that the highest proportions of fish are likely to be entrained into Steamboat Slough and Sutter Slough on the ascending and descending limbs of the tidal cycle, when flow changes from positive to negative. Our findings characterize how patterns of entrainment vary with tidal flow fluctuations, providing information critical for understanding the potential effect of management actions (e.g., fish guidance structures) to modify routing probabilities at this location.

Introduction of Bluefin Killifish (Lucania goodei) into the Sacramento–San Joaquin Delta

Biological invasion by non-native species has been identified as one of the major threats to native fish communities worldwide. The fish community of San Francisco Estuary is no exception, as the estuary has been recognized as one of the most invaded on the planet and the system has been impacted significantly by these invasions. Here, we summarize the introduction and probable establishment of a new species in the Sacramento–San Joaquin Delta, the Bluefin Killifish (Lucania goodei), as discovered by the US Fish and Wildlife Service Delta Juvenile Fish Monitoring Program (DJFMP). The DJFMP has conducted a large-scale beach seine survey since 1976, and it is the longest-running monitoring program in the San Francisco Estuary that extensively monitors the shallow-water nearshore habitat. Possibly introduced as discarded aquarium fish within the vicinity of the Delta Cross Channel, Bluefin Killifish is a close relative of the Rainwater Killifish (Lucania parva), another non-native fish species that has been present in the San Francisco Estuary system for decades. Studies in their native range suggest that Bluefin Killifish will fill a similar niche to Rainwater Killifish, albeit with a more freshwater distribution. The potential ecological impact of Bluefin Killifish remains unclear in the absence of additional studies. However, we have been able to track the spread of the species within the Sacramento–San Joaquin Delta through the existence of long-term monitoring programs. Our findings demonstrate the value of monitoring across various habitats for the early detection and proactive management of invasive species.

The effects of morphometric elements of the channel on hydraulic resistance of machine channels of pumping stations

Presents the results of hydraulic studies in pressureless and pressure water conduits, the results of which showed that the dependences obtained for calculating the hydraulic resistance in round pressure pipes cannot be distributed without the corresponding adjustments of pressureless channels (provided that the diameter of the pipe is replaced in the corresponding calculations with a value where hydraulic radius). In particular, it follows (and this is confirmed by the data of the corresponding experimental studies published in the literature) that in the case of pressureless channels, the pressure loss coefficient, and therefore the pressure loss, depends not only on the relative roughness and Reynolds number, but also on the shape of the cross section the channel. Moreover, if for hydraulically smooth pressureless channels this dependence can be considered to a first approximation clarified, then for channels whose wetted surface is characterized by the presence of a certain roughness, the question of its influence, as well as the shape of the channel cross section on the pressure loss, is far from roughly approximate solution. The paper also considers the general equation of fluid motion in pressureless channels and the functional dependences of the coefficient of hydraulic friction on the Reynolds number, relative roughness, and on the shape of the living section of the channel; resistance formulas are first for the simplest with respect to the cross-sectional shape of the channels (round and infinitely wide rectangular), and then for channels with a more complex cross-sectional shape. To take into account the effect (on the pressure loss) of the channel cross-sectional shape and the presence of a flow with a free surface in it, additional correction factors are introduced (using the hydraulic radius concept) as well as new dependencies and formulas for determining the hydraulic friction coefficient are given, s taking into account the influence of morphometric elements of the channel on the hydraulic resistance of the machine channels of pumping stations.

Glass flow behaviors in micro-channels during hot embossing

A method is proposed to fabricate the micro-structures of glass with low-cost, mass production and high quality by using hybrid open-mold hot embossing technology. The viscous flow and filling behaviors have a great influence on the deformation of glass micro-structures during hot embossing. The detailed topography characterizations of glass micro-structures were performed to analyze the effect of groove width, types of channel, and processing parameters (embossing temperature, pressure, and holding time) on the deformation and filling modes. The results indicated that glass micro-structures presented a larger deformation at the intersection of mold channels. The deformation ratios of glass micro-structures at the cross channels is 0.25. The larger the groove width, the larger the deformation height of the micro-structures. Also, processing parameters of temperature, pressure, and holding time are strongly correlated with the deformation profile of glass micro-structures. At the conditions of 590 °C, 5 MPa, and 100 s, the maximum aspect ratio of glass micro-structure is about 0.7. Excessive forming stress and residual stress induce the growth of glass cracking, which affects the service life and performance of glass micro-structures. This work provides a better understanding of the relationship between design and fabrication of glass micro-structures.

The Flow Boiling Crisis of Saturated Water in Pipes at High Pressures

The procedures developed by the authors for calculating the distribution of the liquid over the channel cross section in the dispersed-annular flows open up opportunities for more justified modeling of the conditions for the occurrence of a boiling crisis at positive values of the relative enthalpy (quality) of the flow. However, a comparison of the calculated values of the liquid flowrate in the film with the recommended values of critical heat flux (CHF) in water flow boiling in pipes has demonstrated that, in general, there is no obvious correlation between them. An analysis confirms the well-known opinion that a unified model of the flow boiling crisis in pipes cannot be constructed. At the same time, the regularities revealed in calculating the entrainment and deposition of droplets should be considered in developing a crisis model. An increase in CHF with mass flowrate, which was discovered experimentally and accounted for in the reference tables in a wide range of high pressures and mass flowrates, gives us reasons to return to Doroshchuk’s hypothesis about the “deposition crisis.” Application of the correlation for the droplet deposition rate in a disperse-annular flow enabled us to quantitatively verify this correlation. The predictions obtained using this correlation agree well with the tabulated data at a flow quality from 0.15 to 0.40 and mass flowrates above 2000 kg/(m2 s). At the same time, it has been demonstrated that the widespread use of extrapolation of the CHF values recommended in the latest edition of these tables makes them, in fact, not only unreliable but also physically unjustified in a certain range of parameters. This paper identifies several such ranges wherein revision of the tables is essential.

Angular Dependence of Fluctuation Conductivity in BaFe1.9Co0.1As2 Single Crystal

Fluctuation conductivity of electron-doped BaFe1.9Co0.1As2 single crystal is investigated by measurement of electrical resistivity under magnetic fields up to 13 T at different angles of θ = 0, 45 and 90 near mean-field transition temperature, where θ is the angle between the applied magnetic field and the axis perpendicular to the ab plane. The mean-field transition temperature is determined using the peak of dR/dT curves. Using the Aslamazov–Larkin theory, four main regions are identified corresponding to 3D, 2D, 1D, and SW regions, respectively, for each angle at different magnetic fields. The 1D region is a sign of conducting charge strips that are believed that these 1D conducting strips might be responsible for the occurrence of high-temperature superconductivity. Anisotropy increases as it approaches Tc, suggesting unconventional superconductivity that might be due to multiband effects in crystal. Results show that the zero-temperature coherence length in the c-direction ξ(0), the effective distance between the conducting layers d, and the channel cross section s decrease with increase in the magnetic field.

Variations of infiltration capacity with flow hydraulic parameters in permeable stormwater channels

ABSTRACT Permeable channels are commonly adopted for urban stormwater management as an infiltration device. However, in the design of such channels, the effects of flow hydraulic parameters (i.e. water level, channel cross section and flow velocity) on the infiltration capacity of a permeable channel have usually been neglected. In this study, the variations of infiltration capacity with flow hydraulic parameters in permeable channels were investigated in various cases of static and dynamic flows. For the static phase, physical channels models were fabricated in the laboratory and the investigations were performed under ponding condition, while a grassed channel model was constructed for the dynamic phase. The results show that the water level and channel side slope affected the infiltration capacity more than the base width. The results also show that increasing the hydraulic residence time significantly affected the infiltration rate. Observed infiltration rates were used to develop a predictive infiltration model that considers the flow hydraulic parameters by adding them to the Kostiakov model. The use of this infiltration model promises better prediction accuracy of the infiltration rate in permeable channels.

A Review of Secondary Flow in Inertial Microfluidics.

Inertial microfluidic technology, which can manipulate the target particle entirely relying on the microchannel characteristic geometry and intrinsic hydrodynamic effect, has attracted great attention due to its fascinating advantages of high throughput, simplicity, high resolution and low cost. As a passive microfluidic technology, inertial microfluidics can precisely focus, separate, mix or trap target particles in a continuous and high-flow-speed manner without any extra external force field. Therefore, it is promising and has great potential for a wide range of industrial, biomedical and clinical applications. In the regime of inertial microfluidics, particle migration due to inertial effects forms multiple equilibrium positions in straight channels. However, this is not promising for particle detection and separation. Secondary flow, which is a relatively minor flow perpendicular to the primary flow, may reduce the number of equilibrium positions as well as modify the location of particles focusing within channel cross sections by applying an additional hydrodynamic drag. For secondary flow, the pattern and magnitude can be controlled by the well-designed channel structure, such as curvature or disturbance obstacle. The magnitude and form of generated secondary flow are greatly dependent on the disturbing microstructure. Therefore, many inventive and delicate applications of secondary flow in inertial microfluidics have been reported. In this review, we comprehensively summarize the usage of the secondary flow in inertial microfluidics.

Investigation of intrusion effects of a gas diffusion layer into channel cross sections depending on channel parameters of metallic bipolar plates

The constructive design of a flow field layout and the channel cross section parameters from a metallic half- or bipolar plate can have a significant influence on the performance characteristics of a fuel cell. Especially the intrusion effect of Gas Diffusion Layers (GDL) under preload conditions leads to a narrowing of the effective flow channel cross section at the active area. In this work, it is assumed that the intrusion effect is dependent on the channel parameters from metallic channel plates. This aspect is investigated experimentally. First, the developed GDL test bench, as well as the test methodology, is explained. Further, a general definition of the channel parameters is shown. Two general equations will be derived, with this it is possible to calculate the channel parameters and channel cross section area analytically. Furthermore, an analytic-empirical intrusion model is derived and validated based on the measurement results. With the intrusion model, it is possible to calculate the effective cross-sectional area with a good approximation. These results can be used for further investigations, for example for flow simulations. Finally, the investigation results of two variation series are listed. At the first series the parameter channel width (CW) and at the second series the channel-to-rib-ratio (CRR) is varied. The considered two measurement parameters are the intrusion in the channel middle and the channel width reduction. It turns out that the investigated both channel parameters influences the GDL intrusion behavior. Particularly, between the channel width parameter and the intrusion in channel middle, a significant dependency can be determined. In the presented experimental series, a certain channel width can be detected, over that the intrusion does not increase any further. Moreover, in the experimental series the dependency between CRR and intrusion in the middle of the channel as well as between CRR and the channel width reduction can be demonstrated. As the CRR increases, both results tend to decrease. In a concluding error analysis, the test results are critically examined and evaluated. In principle, however, the assumption of the dependence between intrusion effect and channel parameters can be sufficiently proved by means of the developed test bench and the test method.

Exclusive vs. competitive retailing: Overseas vaccine supplier’s channel selection considering profit and social responsibility objectives

Many countries/regions such as UK and China have forbidden cross channel retailing for overseas vaccines to achieve better quality control. Therefore, it becomes a critical decision for an overseas vaccine supplier to select a local retailer: An exclusive retailer helps avoid intense channel competition with the local vaccine supplier (referred to as Exclusive Retailing), while relying on the competitive local vaccine supplier for sale (referred to as Competitive Retailing) might induce the latter’s intense self-competition, which also benefits the overseas vaccine supplier. In this paper, we formulate these two representative channel structures by considering the overseas vaccine supplier’s profit and social responsibility objectives. We build game-theoretical models and derive the equilibrium vaccine prices, supply quantities and the vaccine supplier’s utilities. Interestingly, we find that the overseas vaccine supplier will prefer Competitive Retailing when the overseas vaccine and the local vaccine are highly substitutable, regardless of its objective of profit-seeking or social responsibility seeking. We identify two interactive forces, namely, wholesale price effect and demand varying effect, to interpret the rationality of the overseas vaccine supplier’s preferences over exclusive and Competitive Retailing strategies.

Modular neural networks for quality of transmission prediction in low-margin optical networks

It is estimated that the emergence of digital businesses, and growing dynamic traffic demands for Internet applications, including cloud computing and the Internet of Things, will impact the traffic at unprecedented rates. Thus, to cost-efficiently accommodate these challenging requirements, network operators are motivated to maximize the achieved capacity over deployed links, and design more efficient networks capable of handling a wide range of applications, as well as operate more closely to optimality. On the other hand, as the network elements age, nonlinear impairments increases (which can be translated to increasing the network load) and hence, the system margin and maximum achievable rate decrease. Therefore, in order to increase the capacity of optical networks and extend their life time, an accurate physical model is required to estimate the quality of signal and quantify the margin of lightpaths. In this regard, a machine learning (ML) method is proposed based on the modular neural networks to account the cross channel nonlinear effects in estimating noise power and OSNR of lightpaths. For this, the dependence of the contributed nonlinear component of noise power on the transmitted powers as well as the modulation formats of all channels are considered in this data-model. Indeed, this ML-based model provides a useful tool for per-lightpath power management, as a fundamental element for reducing margins. Results of evaluating various proposed modular models show that, in general, all modular models are able to estimate OSNR of lightpaths, with average accuracy of more than 96.6%. However, the proposed $$ MM_{4} $$ modular model is the model presenting better generalization, being able to correctly estimate OSNR of lightpaths, with average accuracy of 99.2%. Also, $$ MM_{3} $$ model performs better for partially loaded network scenarios (99.3%).

Dimensionless morphological ratios versus stream power variations at bankfull stage in an ephemeral channel

Dimensionless morphological ratios (DMR) generally are used in systemic proposals for stream classification and river restoration projects. Often, such morphometric parameters, including field data from channel cross sections, develop into a template for a given geomorphic reference site. In this study, high-resolution Digital Terrain Models (HRDTMs), combined with orthophotographs from 2018 and ground-based surveys, were used to analyze the spatial variability of DMR in a semi-arid ephemeral stream subject to changes in stream power under bankfull conditions. In particular, a channel reach of 2.7 km in length along the Upper Mula stream in southeastern Spain was chosen to test the relationships between the two types of variables. Rosgen's DMR (width to depth ratio, entrenchment ratio, bank height ratio) and hydraulic data at bankfull stage (flow velocity, Froude number, shear stress, mean stream power and energy gradient, among others) were calculated by 1D hydrodynamic modeling and HRDTMs prior entry of field information. The resulting maps allowed comparison of stream power with DMR in relation to the channel stretch class and bed stability. The results showed similar spatial patterns for the width to depth ratio and the bank height ratio. The average values estimated in bend stretches were lower than along straight and slightly sinuous stretches and very similar to those of sub-reaches from the inflection point to the meander bend apex. However, the entrenchment ratio followed a different pattern, according to which the straight and slightly sinuous stretches were the most entrenched and the bend stretches presented a more moderate average entrenchment ratio. In addition, the energy balance and power gradient also experienced spatial variations in relation to the bed stability and DMR. Only in highly incised sub-reaches were such relationships not significant. The lack of a significant correlation between excess energy and bank height ratio or width to depth ratio over short lag distances was also verified, regardless of the affected bedforms. An ANOVA showed important differences between the straight and slightly sinuous stretches and bend stretches, which were strongly influenced by the incision and entrenchment ratios and the maximum bankfull depth.

Wood‐induced backwater effects in lowland streams

AbstractPlacement of wood in streams has become a common method to increase ecological value in river and stream restoration and is widely used in natural environments. Water managers, however, are often hesitant to introduce wood in channels that drain agricultural and urban areas because of backwater effect concerns. This study aims to better understand the dependence of wood‐induced backwater effects on cross‐sectional area reduction and on discharge variation. A newly developed, one‐dimensional stationary model demonstrates how a reduction in water level over the wood patch significantly increases directly after wood insertion. The water level drop is found to increase with discharge, up to a maximum level. If the discharge increases beyond this maximum, the water level drop reduces to a value that may represent the situation without wood. This reduction predominately depends on the obstruction ratio, calculated as the area covered by wood in the channel cross section divided by the total cross‐sectional area. The model was calibrated with data from a field study in four lowland streams in the Netherlands. The field study showed that morphologic adjustments in the stream and reorientation of the woody material reduced the water level reduction over the patches in time. The backwater effects can thus be reduced by optimizing the location where wood patches are placed and by manipulating the obstruction ratio. The model can function as a generic tool to achieve a stream design with wood that optimizes the hydrological and ecological potential of streams.

Features of the Spatial Localization of Particles in the Coherent Channeling Mode and the Mechanism for the Formation of Controlled Directional Radiation

Features of the spatial evolution of a wave function that describes the motion of fast particles in a planar channel in the coherent channeling mode are considered. It is shown that the interference of eigenstates leads to modulation of the probability density of particle localization in the transverse channel cross section and the longitudinal direction of nonquantized motion if the parametric coupling of longitudinal momentum and the energy of transverse particle motion are taken into account. In the case of a very narrow wave packet, the spatial structure of the probability density is close to the classical particle trajectory. In the case of a particle whose state corresponds to a plane wave before its entrance into the channel, the interference process leads to longitudinal-transverse focusing and the formation of periodically located clusters with a very large probability density. As the entrance angle increases, the position of these clusters approaches the channel walls. In this paper, it is shown that the presence of such clusters leads to the possibility of forming similarly located clusters of excited atoms and nuclei and to a new type of generation of quasicoherent directional radiation.

Inertial focusing in triangular microchannels with various apex angles.

We consider inertial focusing of particles in channels with triangular cross sections. The number and the location of inertial focusing positions in isosceles triangular channels can change with varying blockage ratios (a/H) and Reynolds numbers (Re). In triangular channels, asymmetric velocity gradient induced by the sloped sidewalls leads to changes in the direction and the strength of the inertial lift forces. Therefore, varying the configuration (specifically, angle) of the triangular cross section is expected to lead to a better understanding of the nature of the inertial lift forces. We fabricated triangular microchannels with various apex angles using channel molds that were shaped by a planing process, which provides precise apex angles and sharp corners. The focusing position shift was found to be affected by the channel cross section, as expected. It was determined that the direction of the focusing position shift can be reversed depending on whether the vertex is acute or obtuse. More interestingly, corner focusing modes and splitting of the corner focusing were observed with increasing Re, which could explain the origin of the inertial focusing position changes in triangular channels. We conducted fluid dynamic simulations to create force maps under various conditions. These force maps were analyzed to identify the basins of attraction of various attractors and pinpoint focusing locations using linear stability analysis. Calculating the relative sizes of the basins of attractions and exhaustively identifying the focusing positions, which are very difficult to investigate experimentally, provided us a better understanding of trends in the focusing mechanism.

Microchannels inside bulk PMMA generated by femtosecond laser using adaptive beam shaping.

In this contribution, we report on the generation of internal microchannels with basically unlimited channel length inside of PMMA bulk material by femtosecond laser. A precisely controllable and stable circular channel cross section is obtained by using a spatial light modulator to compensate the writing depth depending spherical aberration. Furthermore, the generation of a rotatable elliptical input beam by adaptive optics ensures a fitting of the beam shaping to the writing direction. In this study, we report on both, the effect of the ellipticity of the input beam and the effect of a correction of the spherical aberration on the circularity of the resulting internal microchannels. Moreover, we demonstrate the application of this writing technique by creating microfluidic testing structures inside of a transparent standard polymer.

Search for WIMP-129Xe inelastic scattering using particle identification in the XMASS experiment

The inelastic scattering of Weakly Interacting Massive Particles (WIMPs) and 129Xe nuclei was searched for in the XMASS experiment. When excited by the inelastic scattering, the nuclei emit 39.6 keV γ-ray. The exposure of the data was 327 kg × 800.0 days. To improve the sensitivity of the signal, the events were classified by their pulse shapes, which discriminates between γ-rays and β-rays. As no significant signal was found, the upper limits of the inelastic channel cross section at the 90% confidence level were set. For a 200 GeV/c 2 WIMP, the limit was 4.1 × 10−39 cm2. This is the most stringent limit of the SD WIMP-neutron interaction.

Hydraulic Model for Accelerated Flows Through Porous Medium in the Form Drag-Dominated Regime

Abstract The pressure drop for steady uniform flows (UF) through low permeability porous media—packed bed of particles (balls and rods) and sand (K<10−7m2)—is predicted using the existing global Hazen-Dupuit-Darcy (HDD) hydraulic model, composed of the viscous and form drag terms. In this work, experiments are performed to generate pressure drop data for accelerated steady flows through porous media for a wide range of low permeability (10−9<K<10−7m2), low porosity (ϕ < 0.4) in the form drag-dominant (λ ≫ 1) flow regime. Using the data, the global spatial acceleration effect that arises due to channel cross section variation is shown to be unaccounted for in the existing global HDD model resulting in inaccurate prediction of pressure drop, with more than 80% error in such situations. A modified hydraulic model is developed, introducing geometric parameters in the drag terms in the existing hydraulic model, to account for the acceleration effects. By comparing the results with experimental data, the proposed modified hydraulic model is shown to predict the pressure drop for accelerated flows in porous media in the form drag-dominant regime, with less than 10% error.