Flow Interference Research Articles

Abstract 11516: Quantification of Regurgitation Through Dual Orifices: Pulsatile in Vitro Analysis with Echocardiography and MRI Assessment

Introduction: Proximal Isovelocity Surface Area (PISA) measurement is widely accepted to quantify mitral regurgitant volume (RVol), but flow convergence (FC) zones are complicated with dual orifices, seen with mitral clipping. This study seeks to investigate how flow through one orifice affects PISA measurement across the other to better quantify RVol in dual orifice conditions. Methods: 3D-printed dual circular orifice models with varying relative areas were integrated into a pulsatile flow phantom simulating left heart flow. One orifice (A) was standardized at 19.6 mm 2 while the other (B) was 1X, 2X, and 3X the area of A in three models. Inter-orifice distance was 5 mm to emulate mitral clipping. Continuous wave doppler echocardiography measured peak velocity and velocity time integral. PISA was performed at four aliasing velocities normalized to peak velocity (V a /V peak ) (10%, 8%, 4%, 2%) to compute RVol with 2D phase contrast MRI as reference. In each model, PISA RVol and percent error was calculated to see how varying the area of B impacts PISA accuracy of A. 4D flow MRI FC data was also collected to visualize the 3D formation of FC zones. Results: Using a high V a /V peak to create distinct FC zones provides a better RVol estimation with PISA, as low V a /V peak will merge the FC zones, overestimating flow across individual orifices. Single factor analysis of variance (ANOVA) of percent error of A across the three models showed no significant difference at high V a /V peak (8%: p=0.80, 10%: p=0.23), but significant difference at low V a /V peak (2%: p=0.010, 4%: p=0.005). High V a /V peak FC zones of orifices are independent from each other; PISA can be measured with standard practices and added together for an accurate total RVol. At low V a /V peak , FC orifice zones overlap with overestimation error increasing with larger B area. This finding suggests that resolving two separate FC zones to minimize flow interference is important for accurate RVol estimate in a dual orifice setting.

A Prototype of Monitoring and Early Warning System of Public Water Flow Interference based on Arduino, Firebase Realtime DB, and Android

The majority of the population uses clean water sourced from the PDAM (Indonesian Regional Water Supply Company) pipeline to meet their daily needs. However, clean water utilization is sometimes not smooth because the upstream's water supply is stalled or the PDAM pipeline disrupted. This disruption that often occurs slowly causes routine community activities, such as bathing or cooking, become stop because clean water is a basic need. Thus, a system is needed to provide early warning when the PDAM water supply starts to have problems so that the community can make initial anticipation. This study designed a prototype of an early warning system using an Arduino-based water flow sensor that records water flow discharge data on the PDAM pipeline and sent to the Firebase Realtime Database to be monitored in real-time through an Android application. The system testing is done by black-box testing, i.e. we check all functions of this system, mainly on sending a warning notification when the water flow debt is at a low rate. In the end, by using this system, the user can prepare themselves early, such as collecting residual water debit in the tub and save water when there is a disruption in PDAM water.

A Prototype of Monitoring and Early Warning System of Public Water Flow Interference based on Arduino, Firebase Realtime DB, and Android

The majority of the population uses clean water sourced from the PDAM (Indonesian Regional Water Supply Company) pipeline to meet their daily needs. However, clean water utilization is sometimes not smooth because the upstream's water supply is stalled or the PDAM pipeline disrupted. This disruption that often occurs slowly causes routine community activities, such as bathing or cooking, become stop because clean water is a basic need. Thus, a system is needed to provide early warning when the PDAM water supply starts to have problems so that the community can make initial anticipation. This study designed a prototype of an early warning system using an Arduino-based water flow sensor that records water flow discharge data on the PDAM pipeline and sent to the Firebase Realtime Database to be monitored in real-time through an Android application. The system testing is done by black-box testing, i.e. we check all functions of this system, mainly on sending a warning notification when the water flow debt is at a low rate. In the end, by using this system, the user can prepare themselves early, such as collecting residual water debit in the tub and save water when there is a disruption in PDAM water.

Two-Phase Flow Effects on Seismic Wave Anelasticity in Anisotropic Poroelastic Media

We study the wave anelasticity (attenuation and velocity dispersion) of a periodic set of three flat porous layers saturated by two immiscible fluids. The fluids are very dissimilar in properties, namely gas, oil, and water, and, at most, three layers are required to study the problem from a general point of view. The sequence behaves as viscoelastic and transversely isotropic (VTI) at wavelengths much longer than the spatial period. Wave propagation causes fluid flow and slow P modes, inducing anelasticity. The fluids are characterized by capillary forces and relative permeabilities, which allow for the existence of two slow modes and the presence of dissipation, respectively. The methodology to study the physics is based on a finite-element uspcaling approach to compute the complex and frequency-dependent stiffnesses of the effective VTI medium. The results of the experiments indicate that there is higher dissipation and anisotropy compared to the widely used model based on an effective fluid that ignores the effects of surface tension (capillarity) and viscous flow interference between the two fluid phases.

Aquifer Characterization and Uncertainty in Multi-Frequency Oscillatory Flow Tests: Approach and Insights.

Characterizing aquifer properties and their associated uncertainty remains a fundamental challenge in hydrogeology. Recent studies demonstrate the use of oscillatory flow interference testing to characterize effective aquifer flow properties. These characterization efforts relate the relative amplitude and phase of an observation signal with a single frequency component to aquifer diffusivity and transmissivity. Here, we present a generalized workflow that relates extracted Fourier coefficients for observation signals with single and multiple frequency components to aquifer flow properties and their associated uncertainty. Through synthetic analytical modeling we show that multi‐frequency oscillatory flow interference testing adds information that improves inversion performance and decreases parameter uncertainty. We show increased observation signal length, sampling frequency, and pressure sensor accuracy all produce decreased parameter uncertainty. This work represents the first attempt we are aware of to quantify effective aquifer parameters and their associated uncertainty using multi‐frequency oscillatory flow interference testing.

Antiliquid-Interfering, Antibacteria, and Adhesive Wearable Strain Sensor Based on Superhydrophobic and Conductive Composite Hydrogel.

Conductive hydrogels are promising multifunctional materials for wearable sensors, but their practical applications require combined properties that are difficult to achieve. Herein, we developed a flexible wearable sensor with double-layer structure based on conductive composite hydrogel, which included the outer layer of silicone elastomer (Ecoflex)/silica microparticle composite film and the inner layer of P(AAm-co-HEMA)-MXene-AgNPs hydrogel. Through covalently cross-linking silicone elastomer on the surface of the hydrogel polymer, we bonded a thin Ecoflex film (100 μm) on the P(AAm-co-HEMA)-MXene-AgNPs hydrogel with robust interface, which can easily adhere to the Ecoflex/SiO2 microparticle composite film by silicone glue. The Ecoflex/SiO2 microparticle composite film endows the strain wearable sensor with superhydrophobic function that could maintain the stability under stretching or bending. Moreover, it can effectively resist the interference of water droplets and water flow. The P(AAm-co-HEMA)-MXene-AgNPs hydrogel exhibits outstanding antibacterial activity to inhibit Staphylococcus aureus, Escherichia coli, and even drug-resistant Escherichia coli. In addition, the flexible wearable sensor exhibited good self-adhesive performance by changing the reaction temperature of hydrogel and can adhere strongly onto various materials. The conductive composite hydrogel reported in this work contributes an innovative strategy for the preparation of multifunctional flexible wearable sensor.

Flow behavior in a contra-rotating transonic axial compressor

This study investigated a three-dimensional flow analysis on a two-stage contra-rotating axial compressor using the Navier–Stokes, continuity, and energy equations with Ansys CFX commercial software. In order to validate the obtained results, the absolute and relative flow angles curves for each rotor in radial direction were extracted and compared with the other investigation results, indicating good agreement. The compressor efficiency curve also was extracted by varying the compressor pressure ratio and compressor efficiency against mass flow rate. The flow results revealed that further distortion of the flow structure in the second rotor imposed a greater increase in the amount of entropy, especially at near-stall conditions. The increase of entropy in the second rotor is due to the interference of the tip leakage flow with the main flow which consequently caused more drops in the second rotor, suggesting that more efficacy of flow control methods occurred in the second rotor than in the first rotor.

Aerodynamic Design Optimization of a Transonic Strut-Braced-Wing Regional Aircraft

The aerodynamic design and fuel burn performance of a Mach-0.78 strut-braced-wing regional jet is investigated through aerodynamic shape optimization based on the Reynolds-averaged Navier–Stokes equations. Conceptual-level multidisciplinary design optimization is first performed to size the strut-braced-wing aircraft for a design mission similar to the Embraer E190-E2, with a design range of 3100 nmi at a maximum capacity of 104 passengers, and a maximum payload of 30,200 lb. For direct performance comparisons, a conventional tube-and-wing regional jet is also sized and optimized based on the same reference aircraft. Gradient-based aerodynamic shape optimization is then performed on wing–body–tail models of each aircraft, with the objective of drag minimization at cruise over a 500 nmi nominal mission. Design variables include twist and section shape degrees of freedom, which are realized through a free-form and axial deformation geometry control system, whereas nonlinear constraints include constant lift, zero pitching moment, minimum wing volume, and minimum maximum thickness-to-chord ratios. Results indicate that the optimizer is capable of mitigating shock formation, boundary-layer separation, and other flow interference effects from each wing design, including those within the wing–strut junction of the strut-braced wing. With year 2020 technology levels, the strut-braced-wing regional jet offers a 12.9% improvement in cruise lift-to-drag ratio over an Embraer E190-E2-like conventional tube-and-wing aircraft, which translates to a 7.6% reduction in block fuel for the nominal mission.

Transition of wake flows past two circular or square cylinders in tandem

This paper presents the dependence of flow transitions and flow regimes on Reynolds number Re (≤ 105) and scaled cylinder center-to-center spacing S* (≤ 10) for two tandem cylinders. Both circular and square cross-sectional geometries are considered, and a comparison of results is made between the two geometries. To do so, data available from the literature are collected, and supplementary numerical simulations are done to complement the literature data so as to provide clear-cut flow maps in the Re–S* domain. We identified the borders of Re- and S*-dependent flows, including steady, unsteady, transition, slender/extended body, alternating reattachment, bistable, and co-shedding flows. The flow interference between two tandem cylinders with S* < S*cr is susceptible to stabilize the flow that requires a higher Re for the onset of vortex shedding than the isolated cylinder counterpart, where S*cr is the critical spacing for the onset of co-shedding flow. Besides, the flow interference generally postpones and advances the onset of secondary vortex shedding associated with the transition from two- to three-dimensional vortex shedding for S* < S*cr and S* > S*cr, respectively. Two flow maps are made for the two geometries, both yielding fundamental contributions toward a better understanding of the flow interference effect on various flow transitions. The flow maps determine the regions of a dearth of knowledge, which future studies may pay attention to. Finally, the drag inversion, hysteresis, and flow patterns in the proximity of the onset of vortex shedding for tandem square cylinders (1.5 ≤ S* ≤ 7) are discussed.

Development of 3‐D Curved Fracture Swarms in Shale Rock Driven by Rapid Fluid Pressure Buildup: Insights From Numerical Modeling

AbstractDespite the variety of studies that have investigated the development of fracture networks during kerogen maturation in organic‐rich shale, the fracture interaction modes and generation mechanisms in three‐dimensions are not yet fully understood. In this study, we introduce a novel numerical approach to model the evolution of fracture swarms with three‐dimensional nonplanar geometries. This model enables precise simulation of the propagation, interplay, and coalescence of the fracture swarms with variable apertures and geometries via solving fluid flow, fracture growth, and stress interference. Our results suggest five basic fracture interaction modes between neighboring fractures. The evolving fracture swarms exhibit simultaneous, alternant, and differential growth characteristics at different development phases. We also elucidate the mechanical mechanisms that determine the evolution of three‐dimensional curved fracture swarms. This work yields an improved understanding of fluid‐driven fracture swarms' development in organic‐rich shale due to rapid fluid generation.

Generate Various Parameters Of Trv Envelope Synthetic Test Circuit

The most basic transient a circuit breaker needs to suffer during its activity is the transient recovery voltage (TRV), started by the electric force system as a characteristic response on flow interference. To test high voltage CBs, direct testing utilizing the force system or short out alternators are not practical. The testing of high voltage Circuit Breakers (CBs) of bigger limit requires huge limit of testing station. An equal infusion of short out current and transient voltage to medium and high voltage circuit breaker (CB) by a synthetic model is examined. Transient recovery voltage is made by a capacitor bank and is applied to CB. An optical set off spark gap has been utilized to interrupt short circuit and to introduce of transient recovery voltage that is applied across the contacts of circuit breaker. Transient recovery voltage examination can never be done totally, as the advancement of circuit breaker development and organization configuration goes on. The most widely recognized way to deal with TRV examination is concerning the supposed planned TRV, in which a suspicion of dismissing association between circuit breaker itself and the innate system recovery voltage is being made. Notwithstanding, it actually is by all accounts qualified to examine what circuit breaker means for transient recovery voltage. An ideal grouping to open/close of reinforcement test article and helper circuit breakers inside suitable chance to infuse of recovery voltage. The impact of reactance of inductive flaw current limiter just as distance to blame in short line issue condition on pace of ascent of recovery voltage. A 4-boundaries TRV synthetic test circuit dependent on equal current infusion technique is planned and mimicked for testing 145kV rating circuit-breakers according to new TRV prerequisites given in IEC 62271-100.

Improving Tight Gas Recovery from Multi-pressure System During Commingled Production: An Experimental Investigation

Commingled production has been widely used as an efficient production method in gas field. However, the interlayer interference of gas flow seriously restricts the improvement of gas recovery. Presently, there are several investigations on commingled production characteristics of multi-pressure system gas reservoirs, but no corresponding improved production methods have been proposed. In this study, commingled production characteristics were studied by conducting simultaneous production (simultaneously opening all gas layers for production) simulation experiments. Subsequently, the mechanism of eliminating interlayer interference was revealed by conducting progressive production (progressively opening each gas layer for production) simulation experiments. Then, the effect of interlayer pressure difference on the gas recovery was studied to evaluate the improvement effect of gas recovery. Finally, the effects of initial temperature and pressure on gas recovery were explored to judge the applicability of the progressive production. All experiments were conducted with full-diameter cores of tight sandstone under conditions of temperature, pressure and gas–water saturation similar to those of the actual reservoirs. Experimental results showed that the gas produced by the high-pressure layer may flow back to the low-pressure layer through the interconnected pipeline at outlet end, thereby inhibiting the production capacity of the low-pressure layer and the gas recovery during commingled production. The progressive production method effectively avoids the occurrence of backflow, reduces the effect of interlayer interference, balances the production contribution ratio of different layers and improves the total gas production and recovery efficiency. The progressive production can improve the gas recovery of all gas layers; however, the improvement effect on the low-pressure layer is much better than on the high-pressure layer. The gas recovery from the low-pressure layer to the high-pressure layer increased by 2.62%, 2.23%, 1.41% and 1.23%, respectively. The increase in interlayer pressure difference can intensify interlayer interference and reduce the gas recovery of both simultaneous and progressive production. However, the greater the interlayer pressure difference (2, 3 and 4 MPa), the better the improvement effect of the progressive production in gas recovery (2.04%, 2.66% and 3.61%). The progressive production is effective for multi-pressure system with different initial temperatures and pressures.

Distributed optimal congestion control and channel assignment in wireless mesh networks

Wireless mesh networks have numerous advantages in terms of connectivity as well as reliability. Traditionally the nodes in wireless mesh networks are equipped with single radio, but the limitations are lower throughput and limited use of the available wireless channel. In order to overcome this, the recent advances in wireless mesh networks are based on multi-channel multi-radio approach. Channel assignment is a technique that selects the best channel for a node or to the entire network just to increase the network capacity. To maximize the throughput and the capacity of the network, multiple channels with multiple radios were introduced in these networks. In the proposed system, algorithms are developed to improve throughput, minimise delay, reduce average energy consumption and increase the residual energy for multi radio multi-channel wireless mesh networks. In literature, the existing channel assignment algorithms fail to consider both interflow and intra flow interferences. The limitations are inaccurate bandwidth estimation, throughput degradation under heavy traffic and unwanted energy consumption during low traffic and increase in delay. In order to improve the performance of the network distributed optimal congestion control and channel assignment algorithm (DOCCA) is proposed. In this algorithm, if congestion is identified, the information is given to previous node. According to the congestion level, the node adjusts itself to minimise congestion.

The Eckert–Weise effect and energy separation under the flow interference behind side-by-side cylinders

Abstract

Dynamic analysis of the effect of platoon configuration on train aerodynamic performance

The improved delayed detached eddy simulation (IDDES) was used to study the influence of the platoon configuration of trains on its aerodynamic performance. CFD simulations were validated against the wind tunnel test and different mesh refinement to further verify the flow field around the high-speed train. The platoon configuration mainly affects the aerodynamic forces of the tail car of the front train (car3) and the head car of the rear train (car4) through flow interference. The surface pressure distribution of the train and the time domain and frequency domain characteristics of the aerodynamic force under different spacing are analyzed, and the changing law of the aerodynamic force and the lateral stability of the trains are summarized. The boundary layer and slipstream of trains in platoon are also compared with those of single trains. Meanwhile, both the time-averaged and instantaneous near-wake structures are compared for different cases.

Methodology for quantitative risk analysis of domino effects triggered by flood

Flood events impose great distress on chemical industrial areas, since they may cause Natech accidents involving multiple units. Furthermore, escalation vectors exerted by major accidents can trigger knock-on events, so-called domino effects, causing very severe consequences. In the present study, a methodology is proposed to include domino effects triggered by floods in a quantitative risk assessment, by addressing the frequency assessment of flood-induced domino scenarios. A comprehensive procedure is developed, combining the fragility model for unit damage due to floods, probability estimation for domino escalation, and combinatorial analysis for overall scenarios. Moreover, the flow interference due to the layout of chemical industrial areas is explored to calculate the damage probability more accurately. The methodology has been demonstrated by a case study, the changes in risk indexes and damage zones due to Natech domino effects are discussed. The results show that the overall risk significantly increases with respect to conventional scenarios when considering flood-induced Natech events and domino effects, evidencing the importance of risk analysis of Natech-related domino effects. Finally, some prevention measures have been proposed for chemical industrial areas to make them more resilient and safer when it comes to floods.

A study of flow interference and heat transfer between two-cylinders at different orientations

A numerical investigation is carried out for the different orientations of a circular cylinder where the upstream cylinder moves with varying angles α = 0˚, 30˚, 45˚, 60˚, 90˚ with respect to the downstream cylinder in a fixed position at a gap ratio (L/D) of 3 where L is the distance from centre to centre between cylinders and D is the diameter of the cylinder. Reynolds number (Re), is based on cylinder diameter, is kept constant at 200 for all the cases with air as the working medium. The vortex shedding formation is analysed when the vortices from the upwind cylinder interact with the downwind cylinder and give impressive flow patterns. It is observed that the drag and lift coefficients increase for both the cylinders with change in angular position. Strouhal number is calculated with the help of Fast Fourier transformation (FFT) of vorticity magnitude and evaluated for each case. It is observed that the effect of upwind cylinder on downwind cylinder is significant for α = 30˚, 45˚, 60˚ orientation cases and vortex shedding frequency increases for these cases. Further, the investigation is extending on the laminar forced convection heat transfer performance and variation of Nusselt number for the cylinders. Maximum heat transfer is observed for the downwind cylinder at α = 45˚. In contrast, the local Nusselt number does not vary much for the cylinders except for the downwind cylinder at α = 0˚.

Transformational-Decomposition-Method-Based Semianalytical Solutions of the 3D Problem of Oil Production from Shale Reservoirs

SummaryThe primary objective of this study is to develop fast analytical and/or semianalytical (A/SA) solutions for the problem of liquid flow/production and pressure interference in multifractured systems between parallel horizontal wells in ultralow-permeability reservoirs. We propose a new A/SA method that reduces the 3D flow equation into either a simple algebraic equation or an ordinary differential equation (ODE) in a multitransformed space, the inversion of which yields solutions at any point in space and time.In the proposed transformational decomposition method (TDM), a general, fully linearized form of the 3D partial-differential equation (PDE) describing low-compressibility liquid flow through porous and fractured media is subjected first to Laplace transforms (LTs) to eliminate time, and then to successive finite cosine transforms (FCTs) that eliminate either all three dimensions, yielding a simple algebraic equation, or two dimensions, yielding an ODE in space only. Inversion of the solutions of the multitransformed space equations provides solutions that are analytical in space and semianalytical in time. The TDM completely eliminates the need for time and space discretization, thus dramatically reducing the input-data requirements and long execution times of numerical simulations.The Fortran 95 code for the TDM solutions requires limited inputs and is easy to use. Because of the linearity requirements of the Laplace transformation of the underlying PDE, the TDM is only rigorously applicable at greater than the bubblepoint pressure. Using 3D stencils (the minimum repeatable elements in the horizontal well and hydraulically fractured system) as the basis of our study, solutions over extended production times were obtained for a range of isotropic and anisotropic matrix and fracture properties, constant and time-variable production regimes (rates or bottomhole pressures), combinations of stimulated reservoir volume (SRV) and non-SRV subdomains, variable hydraulic-fracture (HF) dimensions, and inner and boundary (toe and heel) stencils.The results were compared with analytical solutions (available for simple problems and domain geometries), as well as with numerical solutions from a widely used, fully implicit 3D simulator that involves very fine discretization of a 3D domain comprising more than 356,000 elements. The TDM solutions were shown to be in excellent agreement with the reference analytical and/or numerical solutions, while requiring a fraction of the memory and execution times of the latter because of the elimination of the need for time and space discretization.The TDM is an entirely new approach for the analysis of low-compressibility liquid flow and pressure interference in hydraulically fractured ultralow-permeability reservoirs. The TDM solutions have the potential to provide a reliable and fast tool to identify the dominant mechanisms and factors controlling the system behavior and can act as the basis for a rapid initial parameter identification in a history-matching process for possible further refinement using full numerical modeling at less than the bubblepoint pressure.

Aerodynamic characteristics of two closely spaced square cylinders in different arrangements

Wind tunnel experiments on flow interference of adjacent (spacing ratio P/B ​= ​1.75) twin square cylinders in various attack angles α were conducted at a Reynolds number of 8.0 ​× ​104 considering both horizontal and diagonal arrangements of models. Investigations on the mean and fluctuating aerodynamic force coefficients, mean and fluctuating wind pressure coefficients, spanwise correlations, power spectrum densities (PSD) of lift, and Strouhal numbers of two cylinders, as well as the inter-cylinder correlations between them, are presented. The results show that the aerodynamic characteristics of two diagonal cylinders differ significantly from those of horizontal ones. Compared with the single-cylinder, the pressure distributions on adjacent cylinders are dramatically changed, leading to the negative drag, attractive lift, or repulsive lift on the downstream cylinder. At small α, diagonal cylinders present stronger mean drag and higher fluctuating forces than horizontal cylinders do. Besides, a stronger spanwise correlation is found for the diagonal ones. The vortex shedding pattern can be divided into four stages for the horizontal arrangement and six for the diagonal case. PSD curves and Strouhal numbers are similar between two cylinders for both arrangements, suggesting that the two closely spaced cylinders act like one bluff body in the vortex shedding.

Three-dimensional visualization of flow pattern near transport airplane model with operating propellers in wind tunnel

This paper presents the experiment results of three-dimensional visualization of flow pattern behind the wing and fuselage of the light transport aircraft (LTA) model with operating propellers in the T-102 TsAGI subsonic wind tunnel (WT). Studying the flow pattern, it is possible to recognize the features of the flow and aerodynamic interference of model elements. As a result of the analysis of the flow pattern and comparison with the previously obtained integral characteristics, the model elements for improving the aerodynamic perfection of the aircraft are revealed. It is shown that at operational angles of attack behind the main landing gear fairing, the vortex flow forms, increasing drag and, apparently, negatively affecting the longitudinal stability characteristics. Vortices are formed behind the flattened tail of the fuselage. Thus, the visualization of the flow with dacron ribbons is an effective method of obtaining flow pattern around the airplane model elements in WT.