Required Flow Rate Research Articles

Identifying suitable boreholes for irrigation in the bedrock regions of the Sahel

AbstractThis study addresses the critical challenge of optimizing borehole drilling techniques and predictive models to improve groundwater utilization for irrigation in Burkina Faso. Initially, the analysis involved drilling 22 boreholes as part of a photovoltaic micro‐sprinkler irrigation project (PRECIS), with only 11 deemed suitable for irrigation, highlighting the difficulty in achieving the required flow rate of 5 m3/h. To enhance the robustness of the study, additional data from 205 high‐yield boreholes provided by the Office National de l'Eau et de l'Assainissement (ONEA) were incorporated. These boreholes, primarily intended for potable water supply, had flow rates often exceeding 5 m3/h. This extensive dataset was crucial in identifying significant predictors of the project flow rate (Qproj), including the flow rate at the end of drilling (QEndBorh) and lithological factors. The predictive model combining QEndBorh and lithological data explained 73.7% of the variance in Qproj, with an adjusted coefficient of determination (R2adj) of 72.4%. The CART (classification and regression tree) regression model effectively identified branches with flow rates suitable for irrigation, such as Terminal Node 3 with a predicted Qproj of 6.67 m3/h and Terminal Node 4 with a predicted Qproj of 10.5 m3/h, demonstrating the model's robustness. These findings underscore the necessity of detailed lithological assessments and advanced predictive modelling to ensure efficient and reliable borehole drilling for irrigation purposes in regions with complex geological conditions.

Investigation of the transferability of calibration between alternative fluids for liquid and dense phase carbon dioxide flow measurement

Carbon Capture Utilisation and Storage (CCUS) technology is pivotal for achieving global emissions reduction goals. The rise in CCUS facilities, with a near doubling of global capture capacity, indicates industry momentum. Robust flow measurement across the CCUS transport and storage networks are essential for commercial contracts, financial incentives, and regulatory compliance since these are underpinned by accurate quantification of the CO2 quantity transferred across the CCUS chain. However, a critical gap exists in verification and quality assurance of flow meters as currently there are no traceable calibration facilities that operates with liquid and/or dense phase CO2. However, globally there are many accredited traceable water and oil calibration facilities in operation, which can meet the required flow rates and meter sizes. An experimental study was then conducted at TÜV SÜD National Engineering Laboratory, UK, and at the Institute for Energy Technologies, NO, to explore the transferability of calibration between water, oil, and CO2 using five flow meter technologies with the aim of providing a preliminary assessment of whether meters calibrated in alternative fluids can accurately measure liquid and supercritical CO2. The results suggest that this approach could work for Coriolis meters. The results also suggest caution in relying solely on using Equations of State to calculate density values and a recommendation is presented to currently employing direct density measurements until a more comprehensive understanding is achieved on Equations of State performance for CO2-rich mixtures. To the best of the author's knowledge this is the first time that such experimental investigation is conducted, and the results shared publicly.

Technical Study for the Development of Air Brake Compressor in Electric Commercial Vehicles

<div>The development of electric commercial vehicles brought up novel challenges in the design of efficient and reliable air brake systems. The compressor is one of the critical components of the air brake system and is responsible for supplying pressurized air to the brake system. In this study, we aimed to gather essential information regarding the pressure and flow rate requirements for the compressor in the air brake system of electric commercial vehicles. We extensively analyzed the existing air brake systems utilized in conventional commercial vehicles. We examined the performance characteristics of reciprocating compressors traditionally employed in these systems. Recognizing the need for novel compressor designs tailored to electric commercial vehicles, we focused on identifying the specifics such as efficiency, performance characteristics, reliability, and cost of the compressor.</div> <div>Our study utilized theoretical calculations to ascertain the optimal pressure and flow rate parameters. By thoroughly evaluating vehicle brake standards and meticulously analyzing relevant data, we gained a comprehensive understanding of the performance requirements for compressors in electric commercial vehicle air brake systems. Our analysis considered various factors, including vehicle weight, stopping distance, and operational conditions, providing valuable insights into the specific needs of these systems.</div> <div>The research results serve as the foundation for developing compressors that are more efficient, reliable, and compatible with electric vehicles equipped with regeneration capabilities. Ultimately, implementing these improvements will raise the standard for safety, reliability, and overall performance in the air brake systems of electric commercial vehicles.</div>

The Use of Hose Reel Irrigation Machines and Energy Efficient Components in Irrigation

The energy consumed for irrigation is one of the most important inputs in crop production. Irrigation water is distributed within the parcel with minimum loss by using winged or gun systems together with a hose reel irrigation machine (HRIM). The increase in the amount of energy consumed for irrigation increases the cost of the unit product. To reduce the unit product cost, irrigation systems must be used with energy-efficiency units. Frequency converters (FC), pressure transmitters (PT), and programmable logic controllers (PLC) are among the components used to provide energy efficiency. A change in the amount of current drawn by the motors according to the changes in the required flow rate in the pumping facilities is possible by using FC, PT, and PLC. In addition, with more than one motor pump pair; it is necessary to use FC and PLC to be used by connecting in parallel, to operate with the principle of co-aging, and to make a soft start. Instantaneous pressure information is transmitted to PLC and FC via a PT to be installed on the collector in the discharge line in systems with parallel-connected pumps. In this way, the motor revolutions used to drive the pumps are changed via FC, in real-time according to the changes in the flow. Thus, pump-motor pairs are operated with the principle of "constant pressure variable flow" and energy savings are achieved.

A comprehensive study for improving the working parameters for the design of a PSA-based oxygen concentrator

Oxygen concentrators (OC) are medical devices that supply oxygen by separating nitrogen from the atmospheric air. The functionality of PSA-based OC majorly depends on internal pressure dynamics, cycle timing accuracy, orifice dimensioning for flow and pressure regulation, selection of zeolite, air moisture content, and others. This study aimed to develop an improved OC with sustainable performance by optimizing these key parameters. Initially, lithium and sodium-based zeolite adsorbents were experimentally compared, and it was determined that lithium-based 13X zeolite with particle size 0.4–0.8 mm is more effective for OC. An optimization study was performed for the orifice diameter for the required flow rate, purity, and pressure. The 1 mm hole diameter orifice was concluded to deliver the most optimal functionality. The results were validated via analytical and numerical study, which can further be interpolated for higher flow rate OC. After investigation, it was concluded that filters having zeolite with 10%–15% alumina would effectively remove moisture from the air for sustainable OC. An intensive experimental study was conducted to evaluate the cycle timing under optimum operating circumstances, and it was determined that the overall cycle timing is 12–14 s, with flushing accounting for 5%–8% and recharging accounting for 8%–10% of production time. The research developed 10 LPM OC with 95% purity, a recovery rate of 38.46%, and a BSF of 57.2 kgs/TPDO2. Later, the OC was certified by an ISO-13485 prototyping facility and tested in various hospitals, followed by commercialization. The system’s performance was found to be superior to that of other commercialized products.

РАСЧЕТ ЭНЕРГЕТИЧЕСКОГО БАЛАНСА МНОГОАГРЕГАТНОЙ ВЕТРОЭНЕРГЕТИЧЕСКОЙ УСТАНОВКИ В УСЛОВИЯХ НИЗКИХ СРЕДНЕПЕРИОДИЧЕСКИХ СКОРОСТЕЙ ВЕТРА

Energy supply of small facilities of the agro-industrial complex of Russia in remote rural areas using wind energy is an urgent task. Classical wind power plants operate efficiently at a wind speed of more than 7 meters per second, but in most of Russia such a wind speed is rare. Therefore, the utilization rate of the installed capacity of a wind farm is only 0.2. (Research Purpose) The research purpose is developing a method of increasing the utilization rate of the installed capacity of a wind farm and calculating its energy balance at average periodic wind speeds from 4 to 6 meters per second. (Materials and methods) To implement the proposed method, a multi-unit wind power plant consisting of wind receiving devices of various types driven by hydraulic pumps was used. As a result, the working fluid is feed into the hydraulic accumulating unit, from where the working fluid is fed to the hydraulic motor, which provides rotation of the generator shaft. (Results and discussion) At a wind speed of 4-11 meters per second, the total supply of the working fluid of all hydraulic pumps is greater than the required flow rate of the hydraulic pump. It was found out that in a typical period with an average periodic wind speed of 4-6 meters per second, the total volume of fluid supply by hydraulic pumps is 605.2; 758.0; 844.6 liters per hour, respectively. At the end of the period, 5.2 and 158.0 to 254.6 liters of liquid remain in the storage unit, which can compensate for calm periods up to 15-20 minutes. (Conclusions) The proposed method for increasing the utilization rate of the installed capacity of a wind power plant provides the required supply of hydraulic fluid at an average periodic wind speed of 4-6 meters per second, the annual utilization rate of the installed capacity of a wind power plant is 40-50 percent.

Theoretical aspects of substantiating the parameters of the working body of an environmentally comfortable spraying unit

The article presents the general structure and operation process of the vibro-hydromachine, which is agrotechnically and ecologically convenient for the agro-industrial complex, does not cause chemical damage to other types of crops in the environment, and ensures that the spraying unit is energy-efficient. The theoretical aspects of determining the main parameters and operating modes of the vibrohydroelectric machine are given (velocity pressure of a hydraulic or pneumatic mixer and the potential energy of settling particles (or kinetic energy at the moment of settling), to ensure the circulation of mixing flows, the required flow rate of jets from the hydraulic mixer nozzles is, fluid pressure force at point A, pressure at point 2 at depth h, measured from the level of point 1, absolute pressure (Pa) at an arbitrary point in the liquid, excessive pressure Pi, flow of working fluid through the sawing device of the unit, insignificance (he). Also, field experiments have shown the performance of the modernized proposed working bodies.

Chinese expert consensus on standardized inhaler device application in stable chronic airway diseases (2023)

Chinese expert consensus on standardized inhaler device application in stable chronic airway diseases (2023)

Study on Raw Water Needs at Cibanten Reservoir Serang Regency, Banten Province

The rural communities of Sukadana and Sukabares in Serang Regency, Banten Province, require clean and quality water. Current water supply of 10 liters per second serves 4,120 people in Sukadana and 500 in Sukabares. Yet, many lack access due to a required flow rate of 21 liters per second for the combined 9,399 population. Additionally, the existing water network is aging and functioning suboptimally due to damage and insufficient volume capacity. Two main reasons, the damaged old network and insufficient water volume supply, necessitate the construction of a new water network by revamping the existing system and enhancing the reservoir capacity. This network planning is designed to serve the community for the next 22 years, aiming toward Indonesia's golden age in 2045. To ensure the provision of clean water, a well-structured Raw Water Network Development is required. A sound network involves meticulous calculations of water demand and availability to formulate an appropriate Water Network System. The study utilizes measurements from a Current Meter at the Cibanten Reservoir and the FJ. Mock method for establishing reliable flow rates. Water demand calculations are based on population growth projections using arithmetic, geometric, and exponential methods, extended to the year 2045. The research indicates that by 2045, the new network will cater to 15,952 individuals, with a required flow rate of 36 liters per second. This will serve domestic households at 20.30 liters per second, social activities at 1.11 liters per second, and non-domestic purposes at 3.86 liters per second, resulting in a total demand of 35.38 liters per second, considering water loss due to evapotranspiration. The available drinking water flow is abundant at 272 liters per second. With the development and improvement of the Clean Water System, this water supply will be sufficient to meet the consumption needs of the communities in Sukadana and Sukabares in the Ciomas sub-district of Serang Regency, Banten Province. Furthermore, the Cibanten Reservoir serves an additional purpose by irrigating 159 hectares of rice fields in Sukadana Village at approximately 87 liters per second, as well as supporting tourism in Serang Regency and the broader Banten Province. The challenge of the Clean Water Network System is being addressed through the construction of this system by the Ministry of Public Works and Housing, Directorate General of Water Resources, SNVT Groundwater and Raw Water, and the Cidanau-Ciujung-Cidurian River Basin Agency, Banten Province.

A portable AFO solution for pneumatic actuator with cable tendon mechanism to assist ankle dorsiflexion

The limited portability of pneumatic pumps presents a challenge for ankle-foot orthosis actuated by pneumatic actuators. The high-pressure requirements and time delay responses of pneumatic actuators necessitate a powerful and large pump, which renders the entire device heavy and inconvenient to carry. In this paper, we propose and validate a concept that enhances portability by employing a slack cable tendon mechanism. By managing slack tension properly, the time delay response problem of pneumatic actuators is eliminated through early triggering, and the system can be effectively controlled to generate the desired force for dorsiflexion assistance. The current portable integration of the system weighs approximately 1.6 kg, with distribution of 0.5 kg actuation part on the shank and 1.1 kg power system on the waist, excluding the battery. A mathematical model is developed to determine the proper triggering time and volumetric flow rate requirements for pump selection. To evaluate the performance of this actuation system and mathematical model, the artificial muscle’s response time and real volumetric flow rate were preliminarily tested with different portable pumps on a healthy participant during treadmill walking at various speeds ranging from 0.5 m/s to 1.75 m/s. Two small pumps, specifically VN-C1 (5.36 L/min, 300 g) and VN-C4 (9.71L/min, 550 g), meet our design criteria, and then tested on three healthy subjects walking at normal speeds of 1 m/s and 1.5 m/s. The kinematic and electromyographic results demonstrate that the device can facilitate ankle dorsiflexion with a portable pump (300–500 g), generating sufficient force to lift up the foot segment, and reducing muscle activity responsible for ankle dorsiflexion during the swing phase by 8% and 10% at normal speeds of 1 m/s and 1.5 m/s respectively. This portable ankle robot, equipped with a compact pump weighing approximately 1.6 kg, holds significant potential for assisting individuals with lower limb weakness in walking, both within their homes and in clinical settings.

ANALYSIS OF THE EFFECT OF CHANGING THE WORKING SUBSTANCE FROM XENON TO ALTERNATIVE INERT GASES ON THE PARAMETERS OF THE HALL-TYPE ELECTRIC PROPULSION SYSTEM

Xenon is the main working substance for Hall-type electric propulsion systems (EPS) because it allows to obtain high performance of the EPS with ease of operation. However, the high cost of xenon affects the overall cost of development and operation of the EPS system with xenon. Therefore, research is being conducted worldwide to explore alternative working substances that can reduce the cost of tests and development of the EPS while maintaining acceptable performance. Transitioning from xenon to an alternative working substance will lead to changes in the thruster parameters, and as a result, requires changes and modifications of EPS systems for exact working substance. This study analyzes the impact of transitioning from xenon to alternative inert gases such as krypton and argon on the Hall-type EPS, including the thruster, power processing unit, working substance storage andfeed system. It is established that the transition to alternative inert gases, even with thruster optimization for the new working substance, leads to a deterioration of all thrusterparameters except specific impulse.The increased power consumption of the thruster will require the development of a new power processing unit. However, if the thruster operates on an alternative working substance with the same power as with xenon, the power processing unit may remain unchanged. The lower density of alternative working substances would necessitate an increase in the storage tank volume, and the lower critical temperature would eliminate the need for heaters to prevent the ingress of the working substance's liquid phase into the accumulator tank of the feed system.In the feed system, only flow restrictors will need to be replaced to ensure the required flow rate of the alternative working substance. It is found that the minimal modifications required for adapting the EPS to an alternative working substance isoccurred when the thruster operates with the same power consumption as it does with xenon.

Modification, Simulation and Demonstration of Laboratory Scale Pelton Turbine for Waterfall Hydropower Plant

To demonstrate the concepts of using waterfall hydropower to generate energy, a Mini-Laboratory Pelton Turbine (MLPT) was designed and simulated. The principle of energy conversion from potential energy of water at high elevation to kinetic energy at lower elevation through gravity fall was used. To achieve relative continuity of supply as in waterfall, a centrifugal pump was used to deliver water into a set of three reservoirs positioned at different heights. Water from the reservoirs through pipes of different diameters was used to drive the pelton Wheel turbine. A pipe matrix that allows combination of water from two or three sources at different heights and different pipe diameters was designed to demonstrate principle of conservation of flow at a junction. In the laboratory scale design, a power of 750 W was targeted. The required flow rates from different heights of reservoirs to deliver the power were used to establish nozzle diameters, rotor size, rotational speeds and power coupling ratios. A simulation of the model was conducted with different heights, pipe diameters and flow combinations using pipe matrix, were conducted using Matlab Simulink environment. The results showed that the velocity of flow under gravity increases with height of water and the force and torque associated with the flow rate increase with flow area and height of water. The sum of flows from matrix pipes was always found to be conserved with a variance of 0.27. For water heights of 7, 9 and 11 m, the nozzle diameter was found to be 19.0, 25.4, and 38.1 mm and the corresponding jet velocities were 11.2, 12.5, and 13.8 m/s. The flow rates for the scenarios were 0.0026, 0.0046 and 0.0103 m3/s. The optimum wheel diameter was 313 mm with a power coupling of 5.6:1. Compared to other models [27, 35] from the direct use of jets from pumps, the results have similar characteristics and geometric profiles. The average velocity is lower but, flow rate is higher due to the influence of larger cross sectional area. Thus, it is possible to produce the same power output using lower pressure heads when flow rate is optimized using nozzle diameter to compensate loss in velocity. Such systems can be used to harness most of the low head waterfall in Nigeria. However, the possibility of harnessing waterfalls to generate electricity for low energy demand such as recreation centers and farm settlements is faced with problem of hard-to-reach water source due to topographic complexities.

Organic Vacuum Pump Fluids for the Vacuum Pumping of Fusion Power Plants

Vacuum pumps are the heart of the fusion fuel cycle, but most currently proposed pumping technologies are not capable of handling the required flow rates and vacuum pressures. Oil-containing vacuum pumps can readily meet the flow requirements, but vacuum fluids will degrade in fusion-relevant environments due to contact with tritium and exposure to high-energy radiation. Here, we describe a methodology to screen vacuum fluid candidates and purify these candidate fluids post oxidation, post exposure to deuterium, and post exposure to gamma radiation (<7.5 MGy) to simulate a process in which vacuum fluids can be recovered and regenerated during the fusion fuel cycle. A series of oils, including a highly purified mineral oil, phenyl silicone oil, and a polyphenyl ether, are shown to be suitable candidates for vacuum pumping. Additionally, we describe a simple purification methodology to remove oxidized functionalities and the associated isotopologues induced by contact with deuterium from the candidate vacuum fluids This purification methodology can also be applied to radiological damage with moderate effect. Finally, we demonstrate that the sorbents can be regenerated through electromagnetic microwave digestion.

Comparison of Hydraulic Performance of Triangular Side Weirs with a Focus on the Overhang Type

This paper has studied the performance of different triangular labyrinth side weirs. To evaluate the effectiveness of the various schemes: triangulating, adding sloped floors to the cycles, apex overhanging, and changing to an asymmetry plan were experimentally investigated. Continuous improvement has been achieved in these examinations. The average increase of the discharge coefficients relative to the rectangular side weirs was 80, 82, 87, and 96% for triangular side weirs, triangular side weirs with sloped floors, triangular side weirs with sloped floors and overhangs, and asymmetric triangular side weirs with sloped floors and overhangs, respectively. Velocity components near side weirs also confirmed higher performance for the asymmetric plan. Two new equations have been presented to estimate the discharge coefficient of the two-cycle triangular side weirs and triangular side weirs with sloped floors and overhangs. The proposed equation for the triangular side weirs was supported by the present laboratory data, as well as data from other researchers covering different apex angles of 35°, 45°, 60°, 90°, 120°, and 140°. The study results can be used to design triangular side weirs for enhancing the discharge capacity where the channel bank is limited to pass the required flow rate.

Implementation of New Design Concepts to an Axial Compressor and a Case Study with CFD

The present study elaborates on new concepts in designing an axial-flow compressor. With the help of an innovative in-house design code, a rotor design is obtained. Computational fluid dynamics (CFD) was used to explore the level of achievement in the performance of the device with the new attributes. In that, the features including local angle of attack, chord length, camber, and thickness were radially adjusted to fulfill flow rate and pressure head requirements at a specific rotational speed, hub, and tip diameters. At the core of this methodology lies the effective use of a lookup table that interrelates airfoil shapes to their corresponding lift coefficients. The most important outcome was the machine attaining the endurance to stall. Furthermore, the rotor geometry is optimized so that the maximum efficiency coincides with the design point of the device, where a low-pitch air motion with a uniform pressure was observed downstream of the rotor, inducing improved aerodynamic conditions. This leads to the minimization of the tangential stresses, and the level of turbulence remained consistently below 15%, signifying a controlled and efficient flow environment. This research expands the understanding of compressor dynamics and offers a practical design methodology, promising increased operational stability and performance across diverse applications.

Design and experimental analysis of a shell and tube vapor generator for solar thermal vapor absorption refrigeration

The generator is a crucial component of absorption refrigeration system as it provides a major input to the system. The overall performance of the absorption system mainly depends on vapor generation rate in a generator. Various studies are available in the literature on LiBr-H2O vapor absorption refrigeration systems. However, all these studies are focused on the performance of high-capacity commercial systems. Further, detailed analysis and feasibility of generator designs is not well explored though it is an important component of the system. Thus, present novel study is aimed to provide the idea about generator design and performance for a low-capacity system useful for residential applications. The objective of the present work is to investigate the shell and tube heat exchanger as a vapor generator for a vapor absorption refrigeration system experimentally. A LiBr-H2O vapor absorption refrigeration system requires water separation from LiBr in the vapor generator. The vapor generation depends on the saturation temperature and pressure. In this study, a shell and tube heat exchanger is designed for a vapor absorption refrigeration system of 0.5 ton of refrigeration. The experimental investigations are carried out at different operating conditions to evaluate the unit's performance and define its suitability for low-capacity absorption refrigeration system. Considering the output temperature of hot water from the solar thermal collector (80 –90 ℃) and pressure restrictions on the vapor generation process due to the crystallization of lithium bromide, the presented heat exchanger design is evaluated for pressure ranging between −0.90 bar and −0.65 bar. The experimental evaluation revealed that the heat exchanger is the most effective when the inlet temperature is 80 ℃ at a flow rate of 3 L per minute, and the initial pressure is −0.65 bar, while it is least effective for −0.90 bar. Further, vapor generation is greatest at −0.90 bar and lowest at −0.65 bar. The given configuration is suitable for an absorption system of cooling capacity 0.16 to 0.3 TR, as it can supply the vapor at the required flow rate at a given saturation temperature and pressure suitable for the de-absorption of water from LiBr.

Numerical solution of the control problem on the depletion of gas reservoirs with weakly permeable top

The current stage in the development of mathematical and software support for the processes of designing the development of hydrocarbon fields is characterized not only by the improvement of the means of geological and hydrodynamic modeling of reservoir fluid filtration but also by the use of algorithms for optimizing the development of gas deposits. The paper considers the problem of optimal control of the depletion of a gas reservoir with a low-permeability top. Using the so-called Myatiev-Girinsky hydraulic scheme, a two-dimensional equation describing the unsteady gas flow in a reservoir with a jumper is averaged over the capacity of the productive reservoir. This comes down to a one-dimensional equation with an additional term, taking into account gas-dynamic relationships between the reservoir and the jumper. For the numerical solution of process control problems, a formula for the gradient of the functional characterizing the reservoir depletion is found, and the method of successive approximations based on Pontryagin’s maximum principle is applied. In this case, the direct and conjugate boundary value problems are solved by the method of straight lines, and the required flow rate, without taking it beyond the maximum and minimum possible, is found by the gradient projection method with a special choice of step. A brief block diagram of the algorithm for solving the problem is shown; on its basis, a computer program was compiled. The results of calculations are presented to identify the influence of the values of the complex communication parameter not only on the state of the object but also on the operating mode of the well. The expediency of using the presented optimization tool is dictated by an increase in the share of deposits

MP70-04 URETERAL PERISTALSIS LONGITUDINAL MOTION MINIMIZES REFLUX

You have accessJournal of UrologyCME1 Apr 2023MP70-04 URETERAL PERISTALSIS LONGITUDINAL MOTION MINIMIZES REFLUX Kourosh Kalayeh, Haotian Xie, J. Brian Fowlkes, William W. Schultz, and Bryan S. Sack Kourosh KalayehKourosh Kalayeh More articles by this author , Haotian XieHaotian Xie More articles by this author , J. Brian FowlkesJ. Brian Fowlkes More articles by this author , William W. SchultzWilliam W. Schultz More articles by this author , and Bryan S. SackBryan S. Sack More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003338.04AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Lack of sufficient ureteral peristalsis is theorized as one of the mechanisms contributing to ureteral dilation in vesicoureteral reflux (VUR) and non-obstructing megaureters. To help understand the phathophysiologic mechanism for these disorders, we first need to understand the dynamics of normal ureteral peristalsis, which results in near complete clearance of urine from the ureter (i.e., non-dilated). We hypothesize that the clinically observed ureteral wall longitudinal motion is crucial to prevent and/or limit peristaltic reflux (i.e., retrograde flow of urine during an episode of peristalsis). METHODS: To examine this hypothesis, based on the lubrication theory in fluid mechanics, we modeled ureteral peristalsis mathematically as an infinite train of sinusoidal waves and analyzed the antegrade and retrograde flows in the ureter. In doing so, we accounted for ureteral wall longitudinal motion by imposing a periodic Gaussian longitudinal velocity on the wall, Figure 1 (a) and (b), inspired by videos of ureteral operations. RESULTS: Effects of wall longitudinal motion on peristaltic reflux and performance are shown in Figure 1 (c) & (d), and Figure 2 (a) & (b), respectively. The results are shown as an example for a typical clinical case with discharge rate of 1.62 mL/min and peristaltic amplitude of 80 % of lumen diameter. As shown, by considering wall longitudinal motion, the range of urine flow rates resulting in peristaltic reflux drops substantially. The minimum required flow rate to prevent peristaltic reflux drops by 50% when including the wall longitudinal motion effect, Figure 2 (a). Similarly, the required flow rate to limit the reflux volume fraction below a critical value of 2% (chosen as an example, based on clinical expertise) drops by 70%, Figure 2 (b). CONCLUSIONS: This computational model is the first to include longitudinal wall motion, which aligns with our hypothesis that it is important for minimizing peristaltic reflux. This supports the clinical observation of normal ureters having high emptying ability and helps direct further investigations to understand ureteral disorders. Source of Funding: This research has been partially supported by grants from the Michigan Institute for Clinical and Health Research (MICHR), and the Departments of Urology and Radiology at the University of Michigan © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e1004 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Kourosh Kalayeh More articles by this author Haotian Xie More articles by this author J. Brian Fowlkes More articles by this author William W. Schultz More articles by this author Bryan S. Sack More articles by this author Expand All Advertisement PDF downloadLoading ...

Design and Characterization of an Adjustable Passive Flow Regulator and Application to External CSF Drainage

Passive valves that deliver a constant flow rate regardless of inlet pressure changes have numerous applications in research, industry, and medical fields. The present article describes a passive spring valve that can be adjusted manually to deliver the required flow rate. The valve consists of a movable rod with an engraved microchannel. The fluidic resistance of the device varies together with the inlet pressure to regulate the flow rate. A prototype was made and characterized. Flow-rate adjustment up to +/-30% of the nominal flow rate was shown. A simple numerical model of the fluid flow through the device was made to adapt the design to external ventricular drainage of cerebrospinal fluid (CSF). Some insights about the implementation of this solution are also discussed.

Flow Analysis of a Novel, Three-Way Cartridge Flow Control Valve

Flow control valves are designed to maintain a constant flow rate regardless of pressure changes. However, standard, two-way design may cause significant energy losses due to the need to maintain high pressure in the supply line. In contrast, the proposed three-way valve allows the required flow rate to be obtained at a supply pressure slightly above the loading pressure. This work included building mathematical and simulation models, conducting numerical simulations in Ansys/Fluent and Matlab/Simulink environments, and verifying the results by initial test bench experiments on a valve prototype. The main contribution provided by the work concerns the proposal of a new valve solution and the estimation of its operational characteristics.