Wave Flow Research Articles

Wave function renormalization and flow of couplings in asymptotically safe quantum gravity

Wave function renormalization and flow of couplings in asymptotically safe quantum gravity

Cardiac contractility is a key factor in determining pulse pressure and its peripheral amplification.

Arterial stiffening and peripheral wave reflections have been considered the major determinants of raised pulse pressure (PP) and isolated systolic hypertension, but the importance of cardiac contractility and ventricular ejection dynamics is also recognised. We examined the contributions of arterial compliance and ventricular contractility to variations in aortic flow and increased central (cPP) and peripheral (pPP) pulse pressure, and PP amplification (PPa) in normotensive subjects during pharmacological modulation of physiology, in hypertensive subjects, and in silico using a cardiovascular model accounting for ventricular-aortic coupling. Reflections at the aortic root and from downstream vessels were quantified using emission and reflection coefficients, respectively. cPP was strongly associated with contractility and compliance, whereas pPP and PPa were strongly associated with contractility. Increased contractility by inotropic stimulation increased peak aortic flow (323.9 ± 52.8 vs. 389.1 ± 65.1 ml/s), and the rate of increase (3193.6 ± 793.0 vs. 4848.3 ± 450.4 ml/s2) in aortic flow, leading to larger cPP (36.1 ± 8.8 vs. 59.0 ± 10.8 mmHg), pPP (56.9 ± 13.1 vs. 93.0 ± 17.0 mmHg) and PPa (20.8 ± 4.8 vs. 34.0 ± 7.3 mmHg). Increased compliance by vasodilation decreased cPP (62.2 ± 20.2 vs. 45.2 ± 17.8 mmHg) without altering , pPP or PPa. The emission coefficient changed with increasing cPP, but the reflection coefficient did not. These results agreed with in silico data obtained by independently changing contractility/compliance over the range observed in vivo. Ventricular contractility plays a key role in raising and amplifying PP, by altering aortic flow wave morphology.

Gas Hydrate Formation and Slurry Flow Characteristics of Gas–Liquid–Solid Multiphase Systems

Hydrate formation, aggregation, and deposition have become major hazards for the safe transportation of oil and gas pipelines. Although there has been a great deal of research into the behavior of particles during hydrate formation and transport, there is less research into the multiphase generation and flow characteristics of hydrate gas and liquids. In this paper, the flow characteristics of hydrate slurry and the flow pattern transition in gas–liquid multiphase system were studied, and the generations of it were compared between a gas–liquid multiphase system and oil–water emulsion system. The results showed that the flow parameters such as pressure, pressure drop, and density fluctuated more drastically in the gas–liquid system than that in the emulsion system, the higher fluctuation meant a higher risk of pipe plugging. At the same time, the influence of pressure and dosage on multiphase flow pattern transformation and boundary change conditions were studied. A gas-slurry flow pattern transformation diagram was drawn based on the defined transformation conditions between flow patterns. The results also indicated that, with the increase of pressure from 5 to 6 MPa, the boundary of slug flow and air mass flow changed to the direction of higher gas and liquid flow velocity. While the boundary of slug flow and wave flow, stratified flow and wave flow changed to the direction of higher gas flow velocity. The boundary of slug flow and air mass flow changed to the direction of lower liquid flow velocity. In contrast, the boundary of slug flow and wave flow, stratified flow and wave flow, slug flow and stratified flow changed to the direction of higher gas flow velocity and lower liquid flow velocity in the 1% inhibitor period compared with that without the inhibitor. This study will provide theoretical references and technological supports for the safety of multiphase transportation pipelines and the safety of deep water production.

Thermodynamic Concepts in Civil Engineering

Thermodynamics is not always done well or usefully brought to bear in civil engineering. This paper addresses historical aspects of misunderstandings of thermodynamic concepts; applies the Second Law of Thermodynamics to applications including shock waves in compressible fluid flow, the tidal bore, spillway flow , and junction flow. Additional applications of thermodynamics in civil engineering are discussed. These include deriving hydraulic transient wave celerities for waterhammer analyses; the First Law of Thermodynamics for a closed system and for a control volume; one-dimensional flow, energy loss due to friction; parallel incompressible flow; application of the control volume to a pressure conduit; the modified Bernoulli equation; tees with small inflow and outflow branches; isentropic flow of a perfect gas and its application to flow metering, determination of choked flow conditions, and determination of the shaft power required to drive a blower.

Acoustofluidic control of chemical concentration within picoliter droplets in a disposable microfluidic chip

We propose an acoustofluidic method to dynamically control the chemical concentration (CC) within picoliter-scale droplets at high-throughput production exceeding 2000 drops per second. Co-flowing laminar streams of two fluids were rapidly mixed via acoustic streaming flow-induced micro-vortices, and the mixing index was precisely controlled by modulating the wave amplitude. The mixed aqueous sample was fed into a T-junction as a dispersed phase with a continuous phase oil to produce droplets. We conducted numerical and experimental analysis on the flow mixing in terms of the flow rate and wave amplitude. We produced the droplets with tunable CCs with higher than 100-fold enhancement and the droplet libraries with varying inter-droplet chemical concentration (CCD) gradients. The temporal stability and dynamic controllability of the CCD were also verified by the experiments. We demonstrated the applicability of the proposed method by generating doxorubicin-loaded droplets with tunable CCs. The proposed device includes a disposable microfluidic chip to enable the reusable transducer on the piezoelectric substrate, leading to improved flexibility and functionality. We expect that the proposed method to produce droplet libraries with desired CCs is promising for various droplet microfluidic applications including high-through drug screening and discovery, combinatorial biochemistry, and synthesis of functionalized hydrogels.

Environment-Adaptable Rotational Energy Harvesters Based on Nylon-core Coiled Carbon Nanotube Yarns.

Owing to increasing amount of research on energy harvesting, studies on harvesters for practical application and their performance are attracting attention. Therefore, studies on the use of continuous energy as an energy source for energy-harvesting devices are being conducted, and fluid flows, e.g., wind, river flow, and sea wave, are widely used as input energy sources for continuous energy harvesting. A new energy-harvesting technology has emerged based on the mechanical stretch and release of coiled carbon nanotube (CNT) yarns, which generate energy based on the change in the electrochemical double-layer capacitance. First, this CNT yarn-based mechanical energy harvester is demonstrated, which is applicable to various environments where fluid flow exists. This environment-adaptable harvester uses rotational energy as the mechanical energy source and is tested in river and ocean environments. Moreover, an attachable-type harvester for the application of the existing rotational system is devised. In the case of a slow rotational environment, a square-wave strain-applying harvester has been implemented, which can convert sinusoidal strain motion into square-wave strain motion for high output voltages. To achieve high performance of practical harvesting applications, a scale-up method for powering signal-transmitting devices has been implemented.

A unified steady and unsteady formulation for hydrodynamic potential flow simulations with fully nonlinear free surface boundary conditions

This work discusses the correct modeling of the fully nonlinear free surface boundary conditions to be prescribed in water waves flow simulations based on potential flow theory. The main goal of such a discussion is that of identifying a mathematical formulation and a numerical treatment that can be used both to carry out transient simulations, and to compute steady solutions — for any flow admitting them. In the literature on numerical towing tank in fact, steady and unsteady fully nonlinear potential flow solvers are characterized by different mathematical formulations. The kinematic and dynamic fully nonlinear free surface boundary conditions are discussed, and in particular it is proven that the kinematic free surface boundary condition, written in semi-Lagrangian form, can be manipulated to derive an alternative non penetration boundary condition by all means identical to the one used on the surface of floating bodies or on the basin bottom. The simplified mathematical problem obtained is discretized over space and time via Boundary Element Method (BEM) and Implicit Backward Difference Formula (BDF) scheme, respectively. The results confirm that the solver implemented is able to solve steady potential flow problems just by eliminating null time derivatives in the unsteady formulation. Numerical results obtained confirm that the solver implemented is able to accurately reproduce results of classical steady flow solvers available in the literature.

Simulation of the drift and diffusion of marine oil spill under the effect of wind, current and tides

Oil spill accidents occur in marine traffic accidents. Once the accidents happen, oil spill will drift and diffuse on the ocean as impacted by wind and tidal current, which has considerably impacted the work on wharfs and their surrounding environment. This study aimed to investigate the effect of wind, ocean current and tides on oil spill movement for the building of the drift and weathering models of oil particles to predict and assess the risks of oil spill on the ocean. In these models, the oil film drift algorithm considers the joint action of wind, ocean current, wave and density flow on oil spill. In this study, the fluid dynamic model was adopted to determine the drift motion generated by the tidal field, and the diffusion process was calculated with the random walk method. In addition, the random movement model of oil particles was employed for simulating the transport and weathering of the oil spill, as an attempt to simulate marine oil spill. Furthermore, the Ningbo port was taken as an example to obtain the numerical sum of the flow field obtained by the simulation, which can guide the prediction of oil spill risks near ports.

Cinnamomum cassia on Arterial Stiffness and Endothelial Dysfunction in Type 2 Diabetes Mellitus: Outcomes of a Randomized, Double-Blind, Placebo-Controlled Clinical Trial.

Cinnamomum cassia is a medicinal plant whose use has demonstrated benefits on body weight, blood pressure, glucose, and lipids. This study aimed to evaluate the effect of C. cassia on arterial stiffness and endothelial dysfunction (ED) in patients with type 2 diabetes mellitus (T2DM). A randomized, double-blind, placebo-controlled clinical trial was carried out in 18 subjects aged 40-65 years, with a diagnosis of T2DM of one year or less since diagnosis and treated with Metformin 850 mg daily. Patients were randomly assigned to receive either C. cassia or a placebo in 1000 mg capsules, thrice a day, before each meal for 12 weeks. At baseline and after 12 weeks of intervention, brachial-ankle pulse wave velocity and Flow Mediated Dilation were measured, as well as body weight, body mass index (BMI), blood pressure (BP), fasting glucose (FG), glycated hemoglobin A1c (HbA1c), total cholesterol, high density lipoprotein cholesterol, low density lipoprotein cholesterol, and very low density lipoprotein cholesterol, respectively, triglycerides, creatinine, and transaminases. The Mann-Whitney U test for differences between groups and the Wilcoxon signed-rank test for intragroup differences were used, and a P ≤ .05 was considered statistically significant. After C. cassia administration, statistically significant reductions in body weight (81.4 ± 10.4 kg vs. 79.9 ± 9.0 kg, P = .037), BMI (30.6 ± 4.2 kg/m2 vs. 30.1 ± 4.2 kg/m2, P = .018), and HbA1c (53 ± 5.4 mmol/mol vs. 45 ± 2.1 mmol/mol, P = .036) were observed. No changes statistically significant on arterial stiffness, ED, FG, BP, and lipids were observed. C. cassia administration decreases body weight, BMI, and HbA1c without statistically significant changes on arterial stiffness, ED, FG, BP, and lipids. CTR Number: NCT04259606.

Morphological Dynamics on Tidal Inlet System by Generating Variability of Tidal-Wave Energy Regimes; A Process-Based Model Approach of Tide Dominated Case and Mixed Tide Dominated Case

A process-based approach of 2D morphodynamic modeling is an alternative technique to investigate the morphological evolution in the long-term period. In the conceptual model application, there is two methodologies of morphodynamic model; realistic-based model (short time scale model in days/months) and realistic-analogue model which is called process-based model (long time scale model in ~100 years). Realistic-based model is the representative of generating force with complexity of real condition model in the field, however process-based model is the simplification of forcing model by representing the major factor. In this study, the domain model is as the adaptation of Dutch Wadden Zee tidal inlet system. A couple model technique of Flow module (Delft3d) and Wave module (X-Beach) is implemented into the model system. The tidal forcing is based on one main harmonic tidal component of M2 and super harmonic tidal component of M4 and M6 from the analysis harmonic of ZUNO model. The wave forcing is 1.4 m and 330 deg as the representative wave climate condition in Wadden Zee. A process-based model shows that initially the morphological response leading into establish-state condition. Tidal wave propagation which leads to stronger cross-shore ebb-flow perpendicular to the coastline contributes in morphological evolution inside the basin and forming the outer part of the inlet (ebb-tidal delta). Wave induce current in mixed-tide energy case are as the major contribution of stirring up sediments from the sea bed, leads to transport sediment because of longshore currents process, undertow, mass transport.

Transmission model of transient flow wave signal in intelligent layered water injection system

Fluid wave code communication is used in layered water injection intelligent monitoring system, but model of fluid transient flow wave signal transmission is still unknown. Based on the fluid energy equation of steady flow, a transmission mathematical model of fluid transient flow wave signal in intelligent layered water injection system was established. The model can accurately describe the transient flow wave transmission characteristics in the tubular string of water injection wells. The transient flow wave signals and influencing factors generated by the ground electric control valve and the downhole water distributor were studied, and the transmission mechanism of the signal in the water injection tubular string was revealed. Studies show that ground and downhole transient flow wave signals are generated by discharge changes caused by changes in the opening degree of the ground valve and the downhole water distributor. The length of the water injection tube has no effect on the downlink transmission of the wellhead signal, but has a certain influence on the uploading of the downhole signal. Numerical calculations show that the flow rate of the water injection tube has a great influence on the amplitude of the pressure signal. The larger flow rate can generate larger signal amplitude, which is beneficial to the signal transmission, signal detection and processing. It was verified by the experiments and simulations that the pressure and flow changes in the downhole and wellhead had good consistency during the transmission of transient flow waves. It is found that the greater the variation of opening degree, the greater the amplitude of transient flow wave signal, which is beneficial to the wave signal transmission. The optimal settings for the valve opening are selected as 100% rightleftarrows 0%. This study has theoretical guiding significance for the design and performance improvement of fluid wave code communication systems.

Exploratory research on bubbles migration behavior and mass transfer capacity evaluation of proton exchange membrane water electrolyzer based on a volume of fluid-coupled electrochemical model

The proton exchange membrane water electrolyzer (PEMWE) is a promising hydrogen production technology from renewable energy. Efficient bubble management is crucial to enhance energy conversion efficiency. In this study, a volume of fluid (VOF)-coupled electrochemical model was developed to investigate the effect of various parameters on bubble migration behavior and mass transfer capacity in a PEMWE. The results showed that plug flow was effective in reducing the shielding effect of bubbles on the bottom wall, whereas film and wave flows led to water starvation and PEMWE performance degradation. High outlet pressure and inlet velocity should be avoided at high current density to reduce the bubble coverage on the bottom wall. To prevent the formation of films and wave flows that decrease the mass transfer capacity of PEMWE, it is recommended to maintain a minimum depth of 1 mm in the anode channel (ACH). The hydrophobic ACH wall is beneficial to reduce the bubble coverage on the bottom wall. Reducing the contact angle of the anode porous transport layer (APTL) from 90° to 50° leads to a 42.9% decrease in bubble coverage on the bottom wall at 3 A/cm2 due to facilitated bubble detachment and increased plug flow height. In addition, the APTL contact angle showed the highest sensitivity in influencing the bubble coverage on the bottom wall. These finding provide valuable guidance for the design and operation of PEMWE.

Thrust characteristics research on continuous rotating detonation engine

Detonation combustion can produce pressure enhancement effect, increasing engine thrust. In this paper, a 2D Euler control equation with chemical reaction is used to solve the periodic flow of the detonation wave in a rectangular plane. The combustion of the air-breathing continuous rotating detonation engine is simulated. The RDE thrust is obtained through the outlet parameters of the engine. The fuel used is hydrogen, with the equivalent ratio to air. The calculation reflects the working condition of the engine running at low speed. The operating conditions of the engine at low speed are calculated, with a low intake pressure and temperature of 300K and 0.2/0.35 MPa respectively. It is found that the thermal efficiency of detonation wave is higher than that of the deflagration wave under low inlet pressure and temperature, and the thrust of RDE is significantly higher than that of the deflagration engine. The pressure enhancement effect of RDE is not as strong as that of detonation wave, so the pressure ratio of detonation wave can not be used to calculate the engine efficiency.

Branched flows of flexural elastic waves in non-uniform cylindrical shells.

Propagation of elastic waves along the axis of cylindrical shells is of great current interest due to their ubiquitous presence and technological importance. Geometric imperfections and spatial variations of properties are inevitable in such structures. Here we report the existence of branched flows of flexural waves in such waveguides. The location of high amplitude motion, away from the launch location, scales as a power law with respect to the variance, and linearly with respect to the correlation length of the spatial variation in the bending stiffness. These scaling laws are then theoretically derived from the ray equations. Numerical integration of the ray equations also exhibit this behaviour-consistent with finite element numerical simulations as well as the theoretically derived scaling. There appears to be a universality for the exponents in the scaling with respect to similar observations in the past for waves in other physical contexts, as well as dispersive flexural waves in elastic plates.

Stagnation Points Beneath Rotational Solitary Waves in Gravity-Capillary Flows

Stagnation points beneath solitary gravity-capillary waves in the weakly nonlinear weakly dispersive regime in a sheared channel with finite depth and constant vorticity are investigated. A Korteweg-de Vries equation that incorporates the surface tension and the vorticity effects is obtained asymptotically from the full Euler equations. The velocity field in the bulk fluid is approximated which allow us to compute stagnation points in the solitary wave moving frame. We show that stagnation points bellow the crest of elevation solitary waves exist for large values of the vorticity and Bond numbers less than a critical value that depends on the vorticity. Remarkably, the positions of these stagnation points do not depend on the surface tension. Besides, we show that when there are two stagnation points located at the bottom of the channel, they are pulled towards the horizontal coordinate of the solitary wave crest as the Bond number increases until its critical value.

Application of a novel PhysioCell apparatus for biopredictive dissolution tests of oral immediate release formulations – A case study workflow for in vitro-in vivo predictions

Biorelevant dissolution tests of oral solid dosage forms open the gate to valid in vitro-in vivo predictions (IVIVP). A recently developed apparatus, PhysioCell, allows mimicking the fluid flow and pressure waves occurring in the human fasted stomach. In this work, we used the PhysioCell to perform IVIVP for vortioxetine immediate-release (IR) tablets: the originator (Brintellix) and generic product candidates (VORTIO). The dissolved drug was monitored in the gastric (StressCell) and intestinal (Collection Vessel) compartments that contained biorelevant media. Simulated intermittent gastric stress at 15 min and “housekeeping wave” at 30 min increased the dissolution of Brintellix formulations only. A mechanistic model that best described the observations involved the first-order tablet disintegration with a stress-induced enhancement for Brintellix, dissolution of solid particles in the StressCell, and drug transfer to the Collection Vessel. Then, a semi-mechanistic pharmacokinetic model with dissolution parameters as inputs simulated vortioxetine plasma concentrations in healthy volunteers after single and multiple dosing of Brintellix. Despite different dissolution characteristics, VORTIO provided similar concentration profiles to the originator. In conclusion, PhysioCell dissolution tests, combined with semi-mechanistic IVIVP, can be successfully used to develop IR dosage forms exhibiting gastric stress-related effects.

Hydrodynamics and Sediment-Transport Pathways along a Mixed-Energy Spit-Inlet System: A Modeling Study at Chincoteague Inlet (Virginia, USA)

Tidal-inlet systems are dynamic features that respond to short-term (e.g., storms) and longer-term processes (e.g., sea-level rise, changes in tidal prism). The Chincoteague Inlet system, located along the northern Eastern Shore of Virginia (USA), is a dynamic coastal complex that experiences rapid change associated with sediment redistribution and a shifting inlet throat due to the southern elongation of adjacent Assateague Island. In this study, a numerical model based on Delft3D with coupled flow–waves, multiclass sediment transport, and morphologic feedback was developed to quantify the hydrodynamic and geomorphic controls within this rapidly evolving inlet–spit system and to develop a more comprehensive understanding of regional to local controls on sediment-transport pathways. Model results show that most of the sand transport along southern Assateague Island is sequestered nearshore and proximally in deeper sinks within Fishing Point, and, of that, only finer sand sizes are transported around the spit, confirming previous analysis and hypothesis. The model also showed that sand transport toward the south increases along Wallops Island and quantified spatially explicit transport trends for selected sediment classes, revealing that coarser sediment bypassing is a punctuated process that is proportional to storms.

DNA origami-designed 3D phononic crystals

Abstract Moulding the flow of phononic waves in three-dimensional (3D) space plays a critical role in controlling the sound and thermal properties of matter. To this end, 3D phononic crystals (PnCs) have been considered the gold standard because their complete phononic bandgap (PnBG) enables omnidirectional inhibition of phononic wave propagation. Nevertheless, achieving a complete PnBG in the high-frequency regime is still challenging, as attaining the correspondingly demanded mesoscale 3D crystals consisting of continuous frame networks with conventional fabrications is difficult. Here, we report that a DNA origami-designed-3D crystal can serve as a hypersonic 3D PnC exhibiting the widest complete PnBG. DNA origami crystallization can unprecedentedly provide 3D crystals such that continuous frame 3D crystals at the mesoscale are realizable. Furthermore, their lattice symmetry can be molecularly programmed to be at the highest level in a hierarchy of symmetry groups and numbers, which can facilitate the widening of the PnBG. More importantly, conformal silicification can render DNA origami-3D crystals rigid. Overall, we predict that the widest hypersonic PnBG can be achieved with DNA origami-designed 3D crystals with optimal lattice geometry and silica fraction; our work can provide a blueprint for the design and fabrication of mesoscale 3D PnCs with a champion PnBG.

On the velocity and frequency of disturbance waves in vertical annular flow with different surface tension and gas–liquid density ratio

In this study, the characteristics of disturbance waves, including velocity, longitudinal size, and frequency, are comprehensively investigated by conducting gas–liquid upward annular flow experiments in a 5 mm tube through the constant electric current method (CECM). The film thickness time trace is recorded with respect to time, and the information on disturbance waves is subsequently extracted. The effect of liquid and gas flow rate, density ratio, and surface tension on the disturbance wave is quantitatively analyzed. A predictive model of the wave velocity based on the shear stress balance of the liquid film is proposed. A physical model for wave frequency prediction is derived on the basis of the mass conservation equation. A simple empirical model with good prediction accuracy of wave frequency is also derived. Compared with existing correlations available in the literature, the newly derived models show better performance under a wide range of flow conditions.

Improving production and prediction of the flow regimes, pressure drop, and void fraction in the perforated horizontal wellbore

This study aimed to investigate how oil production could be improved by experimenting with different distribution methods across multiple profiles. The authors tested five different profiles that included uniform radial airflow (explained in profile 1) and variable radial airflow (explained in profiles 2, 3, 4 and 5) in a perforated horizontal wellbore. In addition, the study predicted the behavior of total pressure drop, superficial mixture velocity and void fraction encountered in different flow patterns (bubble, slug, stratum and stratum wave flow). Flow patterns were predicted using ANSYS Fluent R3 with a borehole length of 3 m and an ID of 0.0381 m. This was designed with 12 perforations opening vertically at the wellbore with a phase angle of 180 and a perforation density of 4 shots per foot to simulate the complex flow in a horizontal wellbore. In the perforated section, there was a fluctuation in the behavior of the parameters, while in the non-perforated section, the behavior remained constant. The behavior of the total pressure drop, the superficial velocity mixtures and the void fraction were also reasonably uniform in profile 1 in the perforated section.In contrast, they were irregular in the other profiles. In profiles 2, 3, 4 and 5, the behavior of the mixture superficial velocity and void fraction was inverse to the total pressure drop. Note that all theoretically calculated pressure drop modes increased as the Reynolds number of the mixture increased. The liquid and air product increased with increasing Reynolds number of mixture flow in the profiles. In contrast, in profile 1, lower production was obtained through all flow patterns due to the influence of the mixture pressure and the friction factor. The Vogels method was used to calculate maximum production from the horizontal wellbore. The convergence between experimental and numerical results was good during all cases (flow patterns), with some difference in the static pressure drop behaviuor occurring during flow patterns (bubble, dispersed bubble and slug flow).