Incoming Fluid Research Articles

Harvesting both wind energy and vibration energy by a zigzag structure with hybrid magnetic and piezoelectric effects

In practical environments, wind energy and vibration energy often coexist. Considering this, we introduce a new energy harvester designed to concurrently harness wind energy and vibration energy by integrating magnetic and piezoelectric effects. This harvester is composed of a zigzag structure and a bluff body. The bluff body is designed to execute galloping under incoming fluid flow and produce outputs, while the zigzag bi-stable structure can harness the energy of base excitation effectively. The introduction of magnetic interaction leads tothe softening-spring characteristic, which is verified by the nonlinear analysis. This softening-spring nonlinearity canenhance the working frequency range of the harvester. The results obtained from the numerical simulations indicate that the interaction of base excitation and wind flow can significantly improve the non-resonance region output. Corresponding validation experiments are carried out. The results are in good agreement with the numerical ones. Under stochastic excitations, the output power obtained from the hybrid scenario can reach 73.04 μW, representing a 16 % increase compared to the pure base excitation scenario.

Numerical Simulation of Fixed-Free End Beam’s Modal Behaviour using Two-Way Coupled Fluid-Structure Interaction Approach

The fluid flow velocity stands as a pivotal parameter with a great influence on the mutual interaction between the fluid domain and structure. This paper focuses on structural deformation, structural velocity, von-Mises stress and frequency response of a fixed-free end beam using two-way coupled fluid-structure interaction within ANSYS Workbench. The parameters such as deformed fluid pressure and velocity were analysed across three diverse flow regimes: laminar, transitional and turbulent – each aligned with distinct fluid velocities. The outcomes show that the total deformation, velocity and von-Mises stress distribution of the fixed-free end beam increase as the inlet fluid velocity increases. As a result, the pressure and velocity distribution in the fluid flow which receiving the resultant or leftover structure deflection also increases as the incoming fluid velocity increases. Furthermore, the analysis probes the frequency response in turbulent flow conditions reveals higher values compared to laminar and transitional flows, albeit within the same natural frequency domain. This observation marks significant vibrational characteristics found in the presence of turbulent flow dynamics.

A comparative study on energy extraction potential of an elastically mounted rigid cylinder and infinitely tensioned cable using the wake oscillator model

The present study compares the vortex-induced vibration (VIV) response of an elastically mounted rigid cylinder (EMRC) and an infinitely tensioned cable (ITC) with regard to energy transfer from the incoming fluid flow to the structure. The response of the EMRC and the ITC under uniform flow is predicted using the wake oscillator model (WOM) for different mass ratios. The study then probed into the energy extraction potential of an EMRC and an ITC having equivalent mass ratios using the instantaneous energy, which gives a comprehensive understanding of the energy transferred from the fluid to the structure during the course of interaction. The energy conveyed from fluid to structure is dependent on the vortex lift force coefficient on the structure and the velocity of the structure. It is found that EMRC performs superior to an ITC from the energy extraction point of view.

Omphacitite formation and fluid-rock interaction processes in an intra-slab eclogite-facies shear zone

We document the formation of omphacitites in the Monviso Lago Superiore Unit (W. Alps) where eclogite-facies, serpentinite-bearing shear zones host ample evidence for intense intra-slab fluid flow. In the first locality studied, a serpentinite-hosted jadeitite block is rimmed by strained omphacitite (with lawsonite pseudomorphs and minor phengite). U-Th-Pb zircon dating yields a protolith age of c.150 Ma, thus pointing to a burial-related replacement of a former Tethyan seafloor material, and revealed a lack of alpine rims. Multi-mineral Rb-Sr dating of the minerals forming this omphacitite rind yields an isochron age of 41.6 ± 0.7 Ma, corresponding to the early exhumation path still within the eclogite-facies. In this case, omphacitization led to the nearly complete replacement of the former prograde jadeitite through solution-precipitation and was followed by crystal-plastic deformation processes.In various Monviso localities, Fe-Ti metagabbro blocks (commonly exhibiting brecciated garnetite fragments) display evidence for intense fluid-rock interactions leading to the formation of decimeter-thick, weakly strained omphacite-dominated rinds (with minor amounts of lawsonite, clinochlore and talc) around the blocks at the contact with the surrounding serpentinite. Partly dissolved zircon crystals separated from omphacitite rimming an eclogitic Fe-Ti metagabbro block only yielded middle-Jurassic protolith ages. This indicates that omphacitite rinds did not overgrow the eclogite blocks but rather replaced metasomatically the garnet-rich eclogitic assemblage. The omphacitization overprint occurred independently of the nature of the protolith (namely, forming after a jadeitite or after an Fe-Ti eclogite) as a consequence of infiltration of externally-derived fluids and subsequent element sequestration from the incoming fluid phase. These observations highlight the extraordinary ability of eclogite-facies metasomatic fluids to nearly totally overprint rocks as resistant and impermeable as Monviso eclogite breccias or jadeitites.

A geochemical model for the transformation of gabbro into vesuvianite-bearing rodingite

Rodingite is a Ca-rich and Si-poor metasomatic rock commonly occurring in association with serpentinites. This rock is characterized by specific mineral assemblages consisting of hydrated garnet, diopside, vesuvianite, epidote-zoisite, chlorite, or prehnite. However, natural rodingites are significantly heterogeneous in mineral composition and vesuvianite occurs only in some extensively rodingitized rocks. Major factors controlling the mineral diversity as well as details on fluid-rock interactions leading to the evolution of mineral and chemical composition during rodingitization have not yet been fully constrained. In this work, we use PHREEQC software to present a geochemical model for the transformation of a mafic rock into vesuvianite-bearing rodingite at a temperature of 300 °C. Through these simulations, we investigate the effect of fluid composition and progress of the metasomatic process on rodingite formation. Our results show that rodingitization requires an open system with a high input of hydrothermal fluid. Additionally, a decrease in the Si/Ca ratio in the metasomatized rock is correlated to an increase in the volume of incoming fluid. Whole rock chemical and mineral composition in natural rodingites are well reproduced by the model. Furthermore, the diversity of mineral parageneses results mainly from different degrees of transformation and only to a lesser extent to the chemical composition of hydrothermal fluid or protolith. The hydrothermal fluid doesn't need to be especially rich in calcium to transform a mafic rock into rodingite, but it must be low in magnesium, silicon, and have a high pH, which is naturally controlled by serpentinization of surrounding ultramafic rocks.

Numerically Investigating the Energy-Harvesting Performance of an Oscillating Flat Plate with Leading and Trailing Flaps

This study investigates the power generation capability of an oscillating wing energy harvester equipped with two actively controlled flaps positioned at the leading and trailing flaps of the wing. Various parameters, including flap lengths and pitch angles for the leading flap and trailing flap, are explored through numerical simulations. The length of the main wing body ranges from 40% to 65% of the chord length, c, while the leading and trailing flaps vary accordingly, summing up to the total length of the flat plate c = 100%. The pitch angles of the two flaps are adjusted within predefined limits. The pitch angle for the leading flap varies between 25° and 55°, while the trailing flap’s angle ranges from 10° to 40° across 298 different simulation scenarios. The results indicate that employing both leading and trailing flaps enhances the power output compared to a wing with a single flap configuration. The trailing flap deflects the incoming fluid more vertically, while the leading flap increases pressure difference across the surface of the main wing body, synergistically improving overall performance. The power output occurs at a specific length percentage: a leading flap of 30%, a main wing body of 50%, and a trailing flap of 20%, with pitch angles of 50°, 85°, and 30°, respectively, increasing the output power increments by 4.39% compared to a wing with a leading flap, 4.92% compared to a wing with a trailing flap, and 28.24% compared to a single flat plate. The highest efficiency for the specified length percentages is 40.37%.

Identifying some regularities of the turbulent steady-state plane-parallel motion of incompressible fluid at the entrance length

This paper investigates the structural changes in the turbulent motion of an incompressible fluid in the hydrodynamic entrance region of plane-parallel pressure motion. Movement in pressure hydromechanical systems usually occurs in a turbulent regime. Studying the patterns of changes in hydrodynamic parameters under conditions of stationary turbulent pressure motion in the inlet region is a very urgent task. The study was carried out on the basis of boundary layer equations. Taking into account the dependence of changes in the kinematic viscosity coefficient that occur between layers of fluid, a boundary value problem was formed. Analytical solutions have been obtained that make it possible to obtain patterns of changes in velocity and pressure in any effective flow section. Based on the general conclusions of the study, solutions were found for two cases: a) the velocity of the fluid entering the cylindrical pipe is constant; b) the velocity of the incoming fluid has a parabolic distribution. For these cases, using computer analysis of the data obtained, general graphs of velocity changes were constructed in various sections along the hydrodynamic entrance region. These graphs, which display the change in velocity along the entire length of the inlet, make it possible to obtain the velocity of fluid movement at any point along the inlet length and estimate the length of the transition zone. The results obtained are among the least studied issues of classical fluid mechanics and are of important theoretical interest. The results obtained are applicable for the correct construction of the hydrodynamic entrance region of machinery. A calculation formula has been obtained to determine the length of the hydrodynamic inlet region

Effect of fluid motions on finite spheres released in turbulent boundary layers

This paper extends the work in Tee et al. (Intl J. Multiphase Flow, vol. 133, 2020, 103462) to investigate the effect of turbulent fluid motions on the translation and rotation of lifting and wall-interacting spheres in boundary layers. Each sphere was released from rest in smooth-wall boundary layers with $Re_\tau =670$ and 1300 ( $d^+=56$ and 116, respectively) and allowed to propagate with the incoming fluid. Sphere and surrounding fluid motions were tracked simultaneously via three-dimensional particle tracking velocimetry and stereoscopic particle image velocimetry in streamwise–spanwise planes. Two-point correlations of sphere and fluid streamwise velocities yielded long positive regions associated with long fast- and slow-moving zones that approach and move over the spheres. The related spanwise correlations were shorter due to the shorter coherence length of spanwise fluid structures. In general, spheres lag the surrounding fluid. The less-dense lifting sphere had smaller particle Reynolds numbers varying from near zero up to 300. Its lift-offs coincided with oncoming fast-moving zones and fluid upwash. Wall friction initially retarded the acceleration of the denser sphere. Later, fluid torque associated with approaching high-velocity regions initiated forward rotation. The rotation, which was long-lived, induced sufficient Magnus lift to initiate repeated small lift-offs, reduce wall friction, and accelerate the sphere to higher sustained velocity. Particle Reynolds numbers remained above 200, and vortex shedding was omnipresent such that the spheres clearly altered the fluid motion. Spanwise fluid shear occasionally initiated wall-normal sphere rotation and relatively long-lasting Magnus side lift. Hence the finite sphere size contributed to multiple dynamical effects not present in point-particle models.

Thermal boundary layer modelling for heat flux prediction of bubbles at saturation: A priori analysis based on fully-resolved simulations

This study presents and investigates uni-directional thermal sub-layer enhancement techniques within the context of an interface tracking method for simulating bubbly flows at saturation. Current discretisation methods on structured and fixed Cartesian grids tend to spread the bubbles' interface region, creating a trade-off between the freely moving nature of the bubble to the detriment of accurately capturing the discontinuous aspect of the interface and variations of properties and fluxes crossing it. Although robust techniques have been described in the literature to ensure energy conservation, less research has been undertaken to develop a methodology to retrieve the non-linear behaviour of quantities in the interface vicinity at a reasonable computational cost. In this study, the discretised bubble surface is used as a basis for addressing several quasi-static radial sub-problems that are bounded by an interfacial constant saturation temperature and a CFD temperature field value. A first approach, based on an analytical solution fitted at each time step using underlying Eulerian field values, has been developed to incorporate near-interface physics. This includes the tangential effect, incoming fluid velocity, and local mean curvature (first order surface approximation). A semi-analytical approach needs to meet certain assumptions to be valid. This is due to its derivation from a simplified plane boundary-layer development or from a spherical diffusion problem which limits its applicability range. Therefore, a second approach based on a uni-directional sub-resolution fed carefully by interpolated velocity and tangential source terms demonstrates promising results as it aligns with the principal variations of the solution. Both methodologies have been applied onto DNS data of a steady rising bubble configuration at low and moderate Reynolds {3.6;62.5} and Prandtl {1;2.5;5} numbers with a constant interfacial temperature after an extensive analysis of the advection-diffusion terms hierarchy. The key aspects to maximise the effectiveness of the sub-resolution method have been clearly identified and discussed. The Sub-resolution shows better applicability to our case study on moderately large thermal layers. The newly predicted interfacial temperature gradient and temperature profile could be re-employed for Eulerian fluxes correction.

Numerical investigation of increasing the efficiency of thermal photovoltaic system by changing the level of heat transfer distribution

In photovoltaic systems, only a small fraction of solar radiation effectively reaches the module's surface and is converted into electrical energy. The unused solar radiation results in elevated cell temperature and reduced electrical efficiency. In the photovoltaic-thermal system, the circulation of fluids such as water or air around the panels allows for the utilization of otherwise wasted thermal energy, leading to increased electrical efficiency and overall system efficiency. The objective of this article is to examine the thermal efficiency of copper and aluminum oxides in photovoltaic systems when combined with nanofluid. The aim is to identify any changes in efficiency that may arise from this combination. This article presents a novel approach by employing a combination of aluminum oxide and copper nanofluids, along with a water mixture, to investigate the influence of key factors on the electrical, thermal, and overall efficiency of photovoltaic systems. These factors encompass incoming radiation levels on the panel surface, fluid inlet temperature in mountainous regions, and absorber temperature. The study aims to analyze and compare the thermal efficiency of copper and aluminum oxide in this particular context. In the present study, the finite volume method is used to solve the equations. According to the research findings, raising the initial temperature of the incoming fluid results in a proportional increase in the outlet temperature. However, it is important to note that the thermal efficiency remains constant regardless of changes in the initial fluid temperature. Furthermore, copper oxide exhibits superior thermal efficiency compared to aluminum oxide, and the use of nanofluids enhances the thermal efficiency of photovoltaic systems.

The benefits of a recuperative layout of an ORC-based unit fed by a solar-assisted reservoir operating as a micro-cogeneration plant

Organic Rankine Cycle -based microcogeneration systems that exploit solar sources to generate electricity and domestic hot water simultaneously are promising solutions for reducing CO2 emissions in the residential energy-intensive sector. Such systems can be assisted by thermal energy storage reservoirs in which water is heated by solar energy and cooled by the direct use of thermal energy for domestic hot water production and acting as heat source of the power plant. An interesting plant layout optimisation involves the adoption of a recuperative heat exchanger to preheat the working fluid before it enters the heat recovery vapour generator, which is fed with the same working fluid leaving the expander. Despite the positive effect of recuperative heat exchanger adoption on the efficiency of the entire plant, the impact on electrical energy production at this microscale is not straightforward to assess as the heat source is represented by the water inside the reservoir and it is not a continuous high- or medium-temperature stream. The lack of experimental analyses in the literature on these applications makes this a debatable question.Thus, to fill this gap and quantitatively assess the benefits introduced by the adoption of a recuperative stage, a wide experimental comparison between recuperative and not-recuperative Organic Rankine Cycle-based power unit layout was performed. To support the experimental analysis, a comprehensive theoretical model of the Organic Rankine Cycle-based plant was developed and validated against experimental data.The experimental campaign demonstrated that the recuperative Organic Rankine Cycle-based unit required a lower working fluid flow rate for a given expander inlet temperature and pressure ratio. Consequently, a higher electrical power can be produced, requiring lower thermal power from a heat source. The reduction in the thermal power absorbed from the heat source, produced by a higher temperature incoming working fluid entering the Heat Recovery Vapor Generator, had a positive effect, allowing a longer-in-time working condition with a higher conversion efficiency intrinsically produced by the recuperative heat exchanger. Considering the annual electricity consumption of 2700 kWh of a family living in a city in central Italy, the contribution given by the recuperative Organic Rankine Cycle plant operating with a reservoir fed by 15 m2 of flat solar panels was 330 kWh, whereas without the recuperative stage, the production was 240 kWh. The cost of electricity saved justified the adoption of a recuperative heat exchanger.

Force impact of a flow of an infinitely deep liquid on a source under ice cover

A characteristic natural factor of the polar regions of the World Ocean and freezing sea areas is the presence of ice cover. The floating ice cover, which determines the dynamic interaction between the ocean and the atmosphere, affects the dynamics of not only the sea surface, but also subsurface waters, while both the ice cover and the entire mass of liquid beneath it participate in the general vertical movement. It is assumed that the ice cover is continuous, that is, its horizontal scales exceed the lengths of the excited waves and, under fairly natural conditions, is modeled by a thin elastic plate, the deformations of which are small and the plate is physically linear. The problem of calculating the force impact of a flow of an infinitely deep homogeneous liquid on a localized source under the ice cover is solved. The problem is solved for the two-dimensional case. Integral representation of the solution for wave drag and lift is obtained, which arise due to the presence of an ice cover and act on the source. The results of calculations of the force action acting on a localized source, simulating a blunt semi-infinite body of finite width, and a dipole, simulating a cylinder, are presented for various values of the oncoming flow velocity and their immersion depth. Numerical calculations show that as the depth of the source immersion increases, the force effect of the fluid flow, which occurs due to the presence of an ice cover, decreases. The dependences of the wave resistance and lift force on the velocity of the incoming fluid flow demonstrate a qualitatively different behavior. The obtained results with different values of the physical parameters included in them make it possible to evaluate the characteristics of ice cover disturbances and its impact on various sources of natural and anthropogenic disturbances observed in real marine conditions.

The Sensor Occlusion SEN0257 on the Infusion Device Analyzer 2 Channel with TFT Display ensures high accuracy in detecting occlusions.

Syringepump and Infuspump function to provide drugs or fluids that are carried out directly and continuously for a certain period of time through a blood vessel. Often encountered problems of blockage or occlusion in the use of infusion pumps and syringe pumps. Occlusion in the infusion device causes the incoming drug fluid to not flow constantly. Occlusion limit set at 20 Psi according to ECRI. To ensure this, proper calibration is required at least once a year. The purpose of this research is to analyze the accuracy of the pressure sensor on the Occlusion measurement on the Infusion Device Analyzer 2 Channel showing TFT. This study has 2 channels so that it can calibrate 2 tools simultaneously. The design of this module uses a Water Pressure Sensor to measure occlusion and a solenoid valve for pressure simulation. When the sensor is depressed, the sensor detects the pressure and is processed by the Arduino. The pressure results are then displayed on a 7-inch TFT LCD in the form of graphs and numbers in real time and stored on the SD card.

The Vortex Effect in Minimally Invasive Percutaneous Nephrolithotomy

To describe the physical principles of the vortex effect to better understand its applicability in minimally invasive percutaneous nephrolithotomy (MIP) procedures. Two acrylic phantom models were built based on the cross-sectional area (CSA) ratio of a MIP nephroscope and access sheaths (15/16F and 21/22F MIP-M™, Karl Storz®). The nephroscope phantom was 10mm in diameter. The access sheaths had diameters of 14mm (CSA ratio: 0.69) and 20mm (CSA ratio: 0.30). The models were adapted to generate hydrolysis, and hydrogen bubbles enhanced flow visualization on a green laser background. After calibration, the experimental flow rate was set to 12.0mL/s. Three 30-second trials assessing the flow were performed with each model. Computational fluid dynamic simulations were completed to determine the speed and pressure profiles. In both models, as the incoming fluid from the nephroscope phantom attempted to move toward the collecting system, a stagnation point (SP) was demonstrated. No fluid entered the collecting system phantom. Utilizing the 14mm-sheath, we observed a random generation of several vortices and a pressure gradient (PG) of 114.4N/m2 between the nephroscope's tip and SP. In contrast, examining the 20mm-sheath revealed a significantly smaller PG (19.4N/m2) and no noticeable vortices were noted. The speed of the fluid and equipment geometry regulate the PG and the vortices field, which are responsible for the production of the vortex effect. Considering the same flow rate, a higher ratio between the CSA of the nephroscope and access sheath results in improved efficacy of the vortex effect.

Computational Fluid Dynamics of Useful Grinding Fluid Flow and Sensitivity Analysis of Grinding Parameters

In the grinding process, a high speed rotating grinding wheel develops a stiff air barrier around it. This air barrier restricts the flow of incoming grinding fluid through a nozzle jet into the grinding zone, and this leads to a considerable amount of grinding fluid being wasted. An insufficient amount of grinding fluid from the nozzle jet not reaching the grinding wheel-workpiece contact zone will result in many defects in the workpiece as well as in the grinding wheel. In this paper, a unique method of air scraper is modelled and simulated in order to impinge the grinding fluid maximum through a thick boundary layer around the periphery of the rotating grinding wheel and the effect of grinding parameters are analyzed and Ugff rate equation established using Box Behnken Design method.

Characterizing the porosity structure and gas hydrate distribution at the southern Hikurangi Margin, New Zealand from offshore electromagnetic data.

The dynamics of accretionary prisms and the processes that take place along subduction interfaces are controlled, in part, by the porosity and fluid overpressure of both the forearc wedge and the sediments transported to the system by the subducting plate. The Hikurangi Margin, located offshore the North Island of New Zealand, is a particularly relevant area to investigate the interplay between the consolidation state of incoming plate sediments, dewatering and fluid flow in the accretionary wedge and observed geodetic coupling and megathrust slip behaviour along the plate interface. In its short geographic extent, the margin hosts a diversity of properties that impact subduction processes and that transition from north to south. Its southernmost limit is characterized by frontal accretion, thick sediment subduction, the absence of seafloor roughness, strong interseismic coupling and deep slow slip events. Here we use seafloor magnetotelluric (MT) and controlled-source electromagnetic (CSEM) data collected along a profile through the southern Hikurangi Margin to image the electrical resistivity of the forearc and incoming plate. Resistive anomalies in the shallow forearc likely indicate the presence of gas hydrates, and we relate deeper forerarc resistors to thrust faulting imaged in colocated seismic reflection data. Because MT and CSEM data are highly sensitive to fluid phases in the pore spaces of seafloor sediments and oceanic crust, we convert resistivity to porosity to obtain a representation of fluid distribution along the profile. We show that porosity predicted by the resistivity data can be well fit by an exponential sediment compaction model. By removing this compaction trend from the porosity model, we are able to evaluate the second-order, lateral changes in porosity, an approach that can be applied to EM data sets from other sedimentary basins. Using this porosity anomaly model, we examine the consolidation state of the incoming plate and accretionary wedge sediments. A decrease in porosity observed in the sediments approaching the trench suggests that a protothrust zone is developing ∼25km seaward of the frontal thrust. Our data also imply that sediments deeper in the accretionary wedge are slightly underconsolidated, which may indicate incomplete drainage and elevated fluid overpressures of the deep wedge.

THE PROCESS OF RESTORING THE IMPELLER OF A CENTRIFUGAL PUMP IN A LASER INSTALLATION

One of the widely used pumps in the oil industry is the centrifugal pump. During the long-term operation of the centrifugal pump, many failures are observed. One of the main failed parts is the impeller. As we know, an integral part of the functionality of a centrifugal pump is its impeller. Without an impeller, no centrifugal force can be generated on the incoming fluid. So, without an impeller, a centrifugal pump cannot work at all. For this reason, failure of the pump impeller had to be eliminated in order to prevent the pump from malfunctioning and to ensure the maximum length of uninterrupted operation of the pump. The main causes of impeller failure are the effects of cavitation, corrosion and erosion. Here, the coating (layer) resistant to corrosion and corrosion on the surfaces of the impeller of the centrifugal pump was considered. Specially for this, in the appropriate LD-2000 laser device, abrasives with different compositions were selected and their technological regime was developed. Ni, Cr, Fe, Si, Mo elements were used as abrasives. Knowing the composition and physical-chemical characteristics of each of these elements, an accurate report of the technological regime was conducted. With this technological regime, it is appropriate to apply a coating (layer) of any thickness to the surface of the working wheels. This process was carried out in the laser center of the Azerbaijan State Oil and Industry University. Keywords: alloy coating, abrasion, corrosion and corrosion resistance, technological mode, laser device. Keywords: alloy coating, abrasion, corrosion and corrosion resistance, technological mode, laser device.

V02-01 THE VORTEX EFFECT IN MINI-PCNL: IMPROVED UNDERSTANDING WITH A PHANTOM MODEL & COMPUTATIONAL FLUID DYNAMICS

You have accessJournal of UrologyCME1 Apr 2023V02-01 THE VORTEX EFFECT IN MINI-PCNL: IMPROVED UNDERSTANDING WITH A PHANTOM MODEL & COMPUTATIONAL FLUID DYNAMICS Willian Ito, Dillon Prokop, Crystal Valadon, Bristol Whiles, Donald Neff, David Duchene, and Wilson Molina Willian ItoWillian Ito More articles by this author , Dillon ProkopDillon Prokop More articles by this author , Crystal ValadonCrystal Valadon More articles by this author , Bristol WhilesBristol Whiles More articles by this author , Donald NeffDonald Neff More articles by this author , David DucheneDavid Duchene More articles by this author , and Wilson MolinaWilson Molina More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003232.01AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Minimally invasive percutaneous nephrolithotomy (MIP) was initially discredited with assumptions of difficult stone fragment retrieval because of the equipment’s smaller size. However, in 2008 Nagele et al. described a hydrodynamic phenomenon that allowed stone retrieval without the aid of endoscopic tools. This study aims to describe the physical principles of the “vortex effect” to better understand its applicability in MIP procedures. METHODS: Two acrylic phantom models were built based on the cross-sectional area (CSA) ratio of a MIP nephroscope and access sheaths (15/16F and 21/22F MIP-M™, Karl Storz®). The nephroscope phantom was 10 mm in diameter. The access sheaths had diameters of 14 mm (CSA ratio: 0.69) and 20 mm (CSA ratio: 0.30). The models were adapted to generate hydrolysis, and hydrogen bubbles enhanced flow visualization on a green laser background. After calibration, the experimental flow rate was set to 12.0 mL/sec. Three 30-second trials assessing the flow were performed with each model. Computational fluid dynamic simulations (CFD) were completed to determine the speed and pressure profiles. RESULTS: In both models, as the incoming fluid from the nephroscope phantom unsuccessfully attempted to move toward the collecting system, a stagnation point (SP) was demonstrated. No fluid entered the collecting system phantom. Utilizing the 14 mm sheath, we observed a random generation of several vortices and a pressure gradient (PG) of 114.4 N/m2 between the nephroscope’s tip and SP. When the 20 mm sheath was examined, a significantly smaller PG (19.4 N/m2) and no noticeable vortices were noted. CONCLUSIONS: The speed of the fluid and equipment geometry regulate the pressure gradient and the vortices field, which are responsible for the production of the vortex effect. Considering the same flow rate, a higher ratio between the cross-sectional area of the nephroscope and access sheath results in improved efficiency of the vortex. Source of Funding: None © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e168 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Willian Ito More articles by this author Dillon Prokop More articles by this author Crystal Valadon More articles by this author Bristol Whiles More articles by this author Donald Neff More articles by this author David Duchene More articles by this author Wilson Molina More articles by this author Expand All Advertisement PDF downloadLoading ...

Analysis of Fluid Flow Characteristics Across the Darrieus Turbine in Irrigation Channels

This study simulated the characteristics of the fluid flow that passes through the Darrieus turbine before installation and testing were carried out. The purpose of knowing the flow characteristics can determine the profile and position of the maximum speed so that the design and placement of the turbine can be improved. The research method was carried out using dynamic fluid computational simulations in three-dimensional form with steady state conditions, discretization using second-order, with convergent conditions when it reached 10-6. The simulation results show that the position of the flow above the turbine had the lowest value because the fluid flowed relatively without disturbance which caused the velocity to had a value almost the same as the incoming fluid velocity. The fluid velocity increased when it was in line 2 and line 3 or across the turbine. This was due to the turbulence generated by the rotation of the turbine. While the speed on line 4 or below the turbine had a lower value than line 2 and line 3. This was due to the position below the turbine so that the turbine rotation did not have an impact on speed. At the four line positions the velocity increased at Y=0.7 m or when the fluid hits the turbine. This increase in fluid velocity was expected to turn the turbine. The results also included the flow distribution in the form of a streamline in several positions where the flow that was in contact with the channel wall had a low velocity value due to friction with the wall.

Numerical modeling of no vent filling of a cryogenic tank with thermodynamic vent system augmented injector

This paper describes a computational procedure to simulate the chilldown and No Vent Filling of a cryogenic tank with a Thermodynamic Vent System (TVS) assisted injector. During No Vent Filling with a TVS augmented injector, the cryogenic liquid coming from a supply tank is divided into two streams prior to entering the target tank; a small portion of the liquid is allowed to pass through a Joule-Thomson valve to produce a mixture of cold liquid and vapor that is used to cool the second stream that carries the bulk of the incoming fluid before it is injected into the tank. The cold stream is also used to cool the surface of the injector, further helping to reduce the tank pressure before it exits to a vacuum. The Generalized Fluid System Simulation Program (GFSSP), a general-purpose flow network code, has been used to simulate the chill and fill process and compare with the test data. The numerical model accounts for a) different regimes of pool boiling heat transfer that occur during tank chilldown, b) condensation of vapor around spray droplets, at the interface of the cooled injector and ullage, and at the liquid–vapor interface, and c) compression of ullage vapor by the rising liquid level. The observed discrepancy between test and predictions for tank pressure is within 20% and tank filling time is within 4%.