Flow Model Research Articles

Numerical study of entropy production and EMHD effects in a peristaltic motion of Prandtl fluid with solid particles and porous medium

Particulate-fluid flow involving chemical reactions plays a crucial role in pharmaceutical manufacturing, catalytic converters, and combustion processes. This research focuses on the analysis of mass and thermal transfer, highlighting the influence of electroosmosis and magnetic forces on the flow of Prandtl fluid through a peristaltic porous micro-channel. In addition, the multiphase flow attitude, affected by chemical reactions, is extensively examined. The flow model is formulated by utilizing the lubrication theory estimation, integrating lengthy-wavelength and creeping flow approximation to simplify the considered problem. To further simplify the problem, Debye linearization is used, resulting in a set of two ordinary differential equations. The outcomes indicate that velocity drops with rising magnetic field, while it enhances with the Helmholtz-Smoluchowski velocity coefficient. Furthermore, thermal distribution increases with greater concentrations of solid fragments and greater magnetic field. These findings provide valuable insights into optimizing mass and thermal conveyance in peristaltic problems, with potential appliances spanning numerous industrial and biomedical areas.

Approximation of sea surface velocity field by fitting surrogate two-dimensional flow to scattered measurements

In this paper, a rapid approximation method is introduced to estimate the sea surface velocity field based on scattered measurements. The method uses a simplified two-dimensional flow model as a surrogate model, which mimics the real submesoscale flow. The proposed approach treats the interpolation of the flow velocities as an optimization problem, aiming to fit the flow model to the scattered measurements. To ensure consistency between the simulated velocity field and the measured values, the boundary conditions in the numerical simulations are adjusted during the optimization process. Additionally, the relevance of quantity and quality of the scattered measurements is assessed, emphasizing the importance of the measurement locations within the domain as well as explaining how these measurements contribute to the accuracy and reliability of the sea surface velocity field approximation. The proposed methodology has been successfully tested in both synthetic and real-world scenarios, leveraging measurements obtained from Global Positioning System (GPS) drifters and high-frequency (HF) radar systems. The adaptability of this approach for different domains, measurement types and conditions implies that it is suitable for real-world submesoscale scenarios where only an approximation of the sea surface velocity field is sufficient.

The viscosity of a partially molten layer in a paleo-orogenic plateau

Orogenic plateaus (e.g., Tibet, Altiplano) are characterized by broad, flat-top topography at high elevation and significantly increased crustal thickness. Partial melt is thought to weaken the middle crust of orogenic plateaus, and thus reduce the viscosity of the crust; however, the amount of partial melt and the magnitude of associated weakening remain unconstrained. The New England Appalachians represent an exposed mid- to lower crustal section of a paleo-orogenic plateau, similar to modern-day Tibet. In this study, we utilize the relationship between the spacing of deformation bands and the compaction length to constrain mid-crustal shear viscosity in a late Devonian migmatite. We find that the viscosity of the middle orogenic crust in the paleo-orogenic plateau of the New England Appalachians is 1017–18 Pa∙s at ∼3–9% melt. This finding is consistent with geophysical models of orogenic channel flow and provides field-based evidence for a significant rheologic transition at low melt-fraction. Our results suggest that the key elements for the formation of a weak, mid-crustal layer in orogenic plateaus are an influx of water and temperatures near the hydrous granite solidus.

Improving fault zones hydrodynamic characterization and simulation in karstified carbonate environments with GLM and IES invers methods

A quantitative and qualitative estimation of groundwater resources is a challenge for water management in the world, especially in carbonated and karstified aquifers. Within these aquifers, fault zones exert a significant influence on groundwater hydrodynamics and transport. Improving the management of this type of aquifer involves better assessment of its hydrodynamics properties. Sustainability and management solutions can be estimated through numerical modeling. In this study hydrodynamic parameter of fault zone in karstified carbonate environments are estimated from cross-hole pumping test data. These estimations allow the simulation and forecasting of fault zone flow and transport. For this purpose, a flow and transport model has been set up using MODFLOW6 and MODPATH7 codes. Inverse modeling of hydrodynamic parameters is performed with the PEST++ code suite, with both the Gauss-Levenberg-Marquardt algorithm (GLMA) and the iterative ensemble smoother (IES) which is a recent approach with few applications so far. Simulation, parameter estimation, and forecasts of drawdown and pollutant travel time through the fault zone have been first evaluated on a synthetic fault zone and are eventually applied to a real-world fault zone of interest in karst carbonate environments. A comprehensive comparison and analysis of GLMA and IES results are performed for parameter estimation, parametric and predictive uncertainties, ensuring a thorough assessment of results. The findings reveal satisfactory levels of uncertainty associated with the hydraulic conductivity field and both flow and transport forecasts. This approach demonstrates its ability to estimate the hydrodynamic parameter field with a high level of accuracy within the internal structures of the fault zone. This study constitutes valuable and reproducible insights into the simulation and forecasts of fault zones in karst carbonate aquifers. The findings are a step forward in groundwater flow and transport simulation of fault zones and provide relevant practical help for the management and protection of water resources in these critical areas of interest.

Bi-level optimization of novel distribution network with VPP and flexible load cluster

To satisfy the power requirements of modern industrial parks, while also enhancing energy efficiency and system economy, a bi-level optimization model is proposed for a novel distribution network, which incorporates a virtual power plant (VPP) and flexible load cluster. The proposed optimization model for the distribution network layer considers factors such as minimum voltage offset and operating cost. It accounts for uncertainties associated with new energy sources, control of the soft open point (SOP), as well as dispatching of the static var compensator (SVC). A normalized normal constraint (NNC) method is used to obtain Pareto front. The power flow model is converted into a normalized cone programming model utilizing second-order cone relaxation technique. The VPP optimization layer aims to achieve the lowest operational cost and comprehensively considers the complementarity of multiple types of distributed energy resources. The bi-level iterative solution is obtained using the analytical target cascading (ATC) method. Finally, the enhanced IEEE 33-node system example demonstrates that the proposed bi-level optimization model effectively reduces the system’s operating cost, optimizes the power flow distribution, and minimizes network losses.

Investigating the Impact of Vessel Geometry on Cerebral Aneurysm Formation using Multi-Phase Blood Flow Models

Cerebral aneurysms represent a life-threatening condition associated with considerable morbidity and mortality rates. The formation of cerebral aneurysms is influenced by various factors, including vessel geometry, blood flow characteristics, and hemodynamic forces. In this study, we investigate the impact of vessel geometry on the formation of cerebral aneurysms utilizing computational fluid dynamics (CFD) simulations for multi-phase blood flow models.More precisely, we employ the Finite Volume Method to numerically solve the Navier-Stokes equations for simulating blood flow. To accurately capture the intricate nature of blood behavior, we utilize a multiphase blood flow model, as blood consists of red blood cells, white blood cells, and platelets suspended in the blood plasma.Our results demonstrate that the local curvature of the vessel has a pronounced effect on the blood flow patterns and hemodynamic forces within the vessel. Specifically, our simulations indicate that an increase in vessel curvature can lead to the formation of regions of high stress and flow stagnation, both of which are known to be associated with an increased risk of aneurysm formation.The current study provides significant insights into the impact of vessel geometry on the formation of cerebral aneurysms. The obtained results may aid in designing treatment and preventive strategies for cerebral aneurysms, while also contributing to the existing body of knowledge on the subject. Additionally, the approach developed in this study can be applied to investigate various other vascular pathologies, including arterial stenosis and atherosclerosis.

Integrated Subsurface Hydrologic Modeling for Agricultural Management Using HYDRUS and UZF Package Coupled with MODFLOW

The present work aims to compare two different subsurface hydrological models, namely HYDRUS and MODFLOW UZF package, in terms of groundwater recharge; thus, both models were coupled with MODFLOW. The study area is an experimental kiwifruit orchard located in the Arta plain in the Epirus region of Greece. A novel conceptual framework is introduced in order to (i) use in situ and laboratory measurements to estimate parameter values for both sub-surface flow models; (ii) couple the developed models with MODFLOW to estimate groundwater recharge; and (iii) compare and evaluate the performance of both approaches, with differences stemming from the distinctive equations describing the flow in the unsaturated zone. Detailed soil investigation was conducted in two soil horizons in the research field to identify soil texture zones, along with infiltration experiments implementing both double-ring and single-ring infiltrometers. The results of the field measurements indicate that fine-textured soils are predominant within the field, affecting several hydrological processes, such as infiltration, drainage, and root water uptake. Field measurements were incorporated in unsaturated zone flow modeling and the infiltration fluxes were simulated with the application of both the UZF package of MODFLOW and the HYDRUS code. The two codes presented acceptable agreement between the simulated and observed hydraulic head values with a similar performance in terms of statistics; however, they produced different results regarding recharge rates in the aquifer as simulated by MODFLOW. HYDRUS produced higher hydraulic head values in the aquifer throughout the simulation, related to higher recharge rates arising from the root water uptake and the capillary effects that are computed by HYDRUS but neglected by the UZF package of MODFLOW.

Prolonged intracranial catheter dwell time exacerbates penumbral stress and worsens stroke thrombectomy outcomes

BackgroundThe duration of mechanical thrombectomy (MT) is a negative predictor of outcomes in acute ischemic stroke (AIS), yet the precise mechanisms are unclear. We investigated whether the placement of large-bore...

A New Multicommodity Network Flow Model and Branch and Cut for Optimal Quantum Boolean Circuit Synthesis

This study introduces a new optimization model and a branch-and-cut approach for synthesizing optimal quantum circuits for reversible Boolean functions, which are pivotal components in quantum algorithms. Although heuristic algorithms have been extensively explored for quantum circuit synthesis, research on exact counterparts remains relatively limited. However, the need to design quantum circuits with guaranteed optimality is increasing, especially for improving computational fidelity on noisy intermediate-scale quantum devices. This study presents mathematical optimization as a viable option for optimal synthesis, with the potential to accommodate practical considerations arising in fast-evolving quantum technologies. We set a demonstrative problem to implement reversible Boolean functions using high-level gates known as multiple control Toffoli gates while minimizing a technology-based proxy called quantum cost—the number of low-level gates used to realize each high-level gate. To address this problem, we propose a discrete optimization model based on a multicommodity network and discuss potential future variations at an abstract level to incorporate technical considerations. A customized branch and cut is then developed upon different aspects of our model, including polyhedron integrality, surrogate constraints, and variable prioritization. Our experiments demonstrate the robustness of the proposed approach in finding cost-optimal circuits for all benchmark instances within a two-hour time frame. Furthermore, we present interesting intuitions from these experiments and compare our computational results with relevant studies, highlighting newly discovered circuits with the lowest quantum costs reported in this paper. History: Accepted by Giacomo Nannicini, Area Editor for Quantum Computing. This paper has been accepted for the INFORMS Journal on Computing Special Issue on Quantum Computing. Funding: This research was supported by the Ministry of Science and Information and Communication Technology, South Korea [Grants 2017R1E1A1A0307098814 and 2020R1A4A307986411]. Supplemental Material: The software that supports the findings of this study is available within the paper and its Supplemental Information ( https://pubsonline.informs.org/doi/suppl/10.1287/ijoc.2024.0562 ) as well as from the IJOC GitHub software repository ( https://github.com/INFORMSJoC/2024.0562 ). The complete IJOC Software and Data Repository is available at https://informsjoc.github.io/ .

Numerical Simulation of the Horizontal Water-Entry Process of High-Speed Vehicles

Based on the RNG k-ε turbulence model and VOF multiphase flow model, a numerical model of horizontal water-entry of the vehicle was established, and the numerical method was verified by experimental results. The cavitation characteristics, fluid resistance, and motion of the vehicle under different conditions were studied during the vehicle’s water-entry process. The results show that the cavitation process can be divided into the cavity development stage, saturation stage, and collapse stage. With the increase in initial velocity and mass of the vehicle, more water vapor will be generated during the water-entry process. The initial velocity of the vehicle had a limited effect on the resistance coefficient. The resistance coefficient in the stable stage remained almost unchanged for vehicles with different masses. Nevertheless, the time interval of the stable stage was shortened, and the resistance coefficient was greater in the gradually increasing stage for the vehicle with a smaller mass. For vehicles with higher initial velocity or smaller mass, the instantaneous velocity decreased faster after it entered the water. The vehicle with a streamlined design was able to reduce the generation of water vapor and decrease fluid resistance and its coefficient, and the vehicle can run farther during the water-entry process.

Thermal-Gas-Elastic Coupling Modeling and Performance Analysis of Foil Cylindrical gas Film Seal Considering Speed Slip, Temperature Jump and Shaft Misalignment

Abstract The Compliant foil cylindrical gas film seal is an advanced sealing technology designed for high-speed and high-temperature conditions in a jet engine. Its design involves using a compliant foil to create a cylindrical sealing surface, achieving adaptive sealing in environments with high pressure differences and rotational speeds. For high-speed and high-temperature operation, a speed slip flow model was established by considering film slip flow, wall temperature jump, foil deformation, and gas viscosity-temperature thermal effects. The variations in the lubrication performance of the foil cylindrical gas film seal with changes in shaft misalignment directions, misalignment angles, and operating parameters were investigated. The speed slip leads to a decrease in gas film lift and an increase in leakage. The wall temperature jump phenomenon caused by speed slip leads to a 2.56% decrease in film temperature. The shaft misalignment angles on the high-pressure and low-pressure sides have different impacts on the flow field, with film pressure and temperature differing by 66.78% and 11.19%, respectively.

A Study of Loss Model Parameter Sensitivity in Compressor Unsteady Flow Simulations

Abstract This article presents results from a comprehensive sensitivity analysis focused on loss models used in a recently developed compressor unsteady mean line flow model for a transonic axial-centrifugal compressor. The mean line flow model treats flow through rotors and stators in their respective reference frames (rotating or stationary), and the compressor performance is determined by the kinetic energy addition and various physics-based loss models in relative frames. In this paper, we describe the modeling approach of the compressor flow model, as well as the loss models that are used to obtain a relatively good match against test data. Sensitivity studies of selected loss model parameters are presented to show the effect of individual loss model parameters on the overall compressor characteristics in the entire speed range. The effects of losses on unsteady flow transients are assessed by comparing the transient responses when a step reduction of throttle area is applied. The comparisons show that the change in loss magnitude has weak effects on transient response if the change of loss does not significantly change the system stability.

Fractional modeling of bioconvection in Jeffrey nanofluids with gyrotactic organisms

AbstractThe current study examines how mass and heat transfer affect mobility of Jeffrey fluid while taking sun radiation across the vertical plate into account. In the polyvinyl alcohol water base fluid, the study combines gyrotactic organisms with copper nanoparticles. Microorganisms classified as gyrotactic respond to gravitational and viscous forces by swimming and orienting themselves, which results in the formation of patterns known as bioconvection, which is the result of the collective movement of these microorganisms. The main goals are to address the growing uses of solar plates by creating a unique mathematical model for flow and thermal properties of the parabolic trough solar collector (PTSC) installed on solar panel. Sunlight is directed onto a single focal line by curved mirrors in PTSCs, which heat the fluid moving over the plate at this focused line. The momentum, heat, and mass equations are solved by the model using Fourier and Fick's laws. The Laplace transform is then used to convert the solution sets into dimensionless Partial differential equation (PDE) for the velocity, energy, and mass fields. The innovative aspect of this model is its in‐depth examination of non‐Newtonian nanofluids, which are boosted by the addition of gyrotactic organisms and copper nanoparticles to increase heat transfer efficiency. The impacts of several factors on flow characteristics, including the Lewis number, mass Grashof number, Grashof number for bioconvection, magnetic and electric parameters, Peclet number, chemical reaction parameter, and Prandtl number, are shown graphically. Increasing the radiation parameters and volume fraction results in a noticeable improvement in the temperature profile. By demonstrating the superior heat transfer capabilities of non‐Newtonian nanofluids in solar energy applications, this work advances the field. It is particularly relevant to microchip cooling, solar energy systems, and thermal energy systems. In summary, the work provides a comprehensive model that advances our understanding of heat and mass transfer in non‐Newtonian nanofluids that are exposed to ambient sunlight. In the future, the model will be employed in real solar energy systems to confirm its effectiveness. The findings have applications in the development of temperature control technology and solar energy systems that are more effective.

Mathematical Models on Mechanics of Biofluids

In this work, we study the mathematical models of flows for some biofluids. In biomechanics, peristaltic flow plays an important role in which the motion generated in the fluid contained in a distensible tube when a progressive wave of area contraction and expansion travels along the wall of the tube. We consider the effect of elasticity of the tube wall in the flow through the progressive wave travelling along its length without its direct calculation. Since the no – slip condition has used on a moving undulating wall surface, it determines the sinusoidal boundary conditions on the upper and lower wall of the tube. The wide occurrence of peristaltic motion gives its result physiologically from neuro-muscular properties of any tubular smooth muscle.

A comparative study of numerical methods for approximating the solutions of a macroscopic automated-vehicle traffic flow model

In this paper, a particle method is used to approximate the solutions of a “fluid-like” macroscopic traffic flow model for automated vehicles. It is shown that this method preserves certain differential inequalities that hold for the macroscopic traffic model: mass is preserved, the mechanical energy is decaying and an energy functional is also decaying. To demonstrate the advantages of the particle method under consideration, a comparison with other numerical methods for viscous compressible fluid models is provided. Since the solutions of the macroscopic traffic model can be approximated by the solutions of a reduced model consisting of a single nonlinear heat-type partial differential equation, the numerical solutions produced by the particle method are also compared with the numerical solutions of the reduced model. Finally, a traffic simulation scenario and a comparison with the Aw-Rascle-Zhang (ARZ) model are provided, illustrating the advantages of the use of automated vehicles.

Flow Characteristics of Asymmetric Plunger Pairs in High-Pressure Plunger Pumps

Abstract The deep-sea submersible is an essential piece of equipment for deep-sea development, serving as a crucial tool for conducting exploration and operations in the deep ocean. As the core component of the hydraulic system, the plunger pump is vital for ensuring the smooth lifting and lowering of the submersible. The plunger pair, which constitutes the most significant friction pair in plunger pumps, plays a pivotal role in determining both the service life and volumetric efficiency of the pump through its friction, lubrication, and sealing performance. This article proposes a flow model for the plunger pair in eccentric and inclined positions, considering its various orientations and placements. It elucidates the deformation and leakage characteristics of the plunger pair under different configurations, including various postures, material properties, and design parameters. The findings not only provide a theoretical foundation for the design of reciprocating seals and the evaluation of sealing performance but also contribute to the broader field of parameter design and performance assessment for other types of gap seals.

Analysis and Application of Particle Backtracking Algorithm in Wind–Sand Two-Phase Flow Using SPH Method

Due to the high sensitivity of grid-based micro-scale wind–sand flow models to deformation and distortion, this study employs the Smooth Particle Hydrodynamics (SPH) method for numerical simulations. The advantage of the SPH method is that it can dynamically analyze the entire trajectory of the particles, thus allowing the initial positional distribution of sand-buried particles to be traced. This study utilizes the advantages of the SPH method. It develops particle backtracking algorithms based on the SPH method using the C language. It analyses the initial location distribution, concentration, velocity, and particle size distribution of sand-buried particles to formulate targeted measures to cope with wind–sand disasters. Meanwhile, this paper improves a particle modeling algorithm to realize arbitrary mixing particle size and mixing ratio by programming in C language and combining it with pixel recognition technology. In addition, this paper will use the particle backtracking algorithm to analyze the classical embankment wind and sand flow field and then propose adequate measures for embankment wind and sand disaster management by investigating sand particle movement characteristics.

Integrated energy microgrids participating in voltage regulation ancillary services: An improved ADMM based distributed optimization approach

AbstractThe integrated energy microgrid (IEM) has good potential for both active and reactive power regulation, which are gradually becoming critical resources for participating in power system ancillary services. This paper constructs a distributed optimization model for the IEMs participating in voltage regulation ancillary services by considering multiple physical network constraints. To reduce computational complexity, the DistFlow power flow model and the second‐order cone relaxation method are introduced to transform the optimization model into a second‐order cone programming problem. Moreover, an improved accelerated consensus alternating direction method of multipliers algorithm is proposed to accelerate distributed optimization solutions of the model while protecting user privacy. Finally, the proposed optimization model and solution method are tested in the modified IEEE‐33 node test case to verify their effectiveness and feasibility.

Research on the Internal Flow and Cavitation Characteristics of Petal Bionic Nozzles Based on Methanol Low-Pressure Injection

This paper aims to discuss the internal flow and cavitation characteristics of petal bionic nozzle holes under different injection pressures to improve the atomization effect of methanol. The FLUENT (v2022 R1) software is used for simulation. The Schnerr-Sauer cavitation model in the Mixture multiphase flow model is adopted, considering the evaporation and condensation processes of methanol fuel to accurately simulate cavitation and internal flow performance. The new nozzle hole is compared with the ordinary circular nozzle hole for analysis to ensure research reliability. The results show that the cavitation of the petal bionic nozzle hole mainly occurs at the outlet, which can enhance the atomization effect. In terms of turbulent kinetic energy, the internal turbulent kinetic energy of the petal bionic nozzle hole is greater under the same pressure. At 1 MPa, its outlet turbulent kinetic energy is 38.37 m2/s2, which is about 2.3 times that of the ordinary circular nozzle hole. When the injection pressure is from 0.2 MPa to 1 MPa, the maximum temperature of the ordinary circular nozzle hole increases by about 33.4%, while that of the petal bionic nozzle hole only increases by 12.3%. The intensity of internal convection and vortex is significantly reduced. The outlet velocity and turbulent kinetic energy distribution of the petal bionic nozzle hole are more uniform. In general, the internal flow performance of the petal bionic nozzle hole is more stable, which is beneficial to the collision and fragmentation of droplets and has better uniformity of droplet distribution. It has a positive effect on improving the atomization effect of methanol injection in the intake port of methanol-diesel dual-fuel engines.

Large Amplitude Dynamic Instability of a Graphene-Reinforced Pipe Conveying Pulsating Flow

In many industries’ applications, one deals with pipes conveying fluid. Besides, the implementation of advanced materials in manufacturing of new-brand structures is developing. Consequently, in this paper, one of the most important dynamics analyzes that an advanced pipe conveying fluid may meet it is addressed. For the first time, linear and nonlinear dynamics of a pipe reinforced with graphene nanoplatelets (GPL pipe) that conveys pulsating flow is presented. The Euler–Bernoulli beam model follows the plug flow model in order to formulate the problem. The method of multiple scales (MMS) applied to the discretized couple nonlinear gyroscopic governing equations with the aim of specifying the instability region and the steady-state response of the GPL pipe subjected to the principal parametric resonance of one of its modes, as a consequence of pulsating flow. Respectively, the Floquet theory and the Runge–Kutta fourth-order (RK4) method are applied to the linear governing equations and nonlinear governing equations for the sake of confirming the current MMS results. It is deduced that a small amount usage of GPL reinforcement phase improves substantially the resistance against static instability, and the critical fluid excitation amplitude fraction, meanwhile declines the instability region bandwidth, and the steady-state response of the pipe. In contrary, it is confirmed that a heavier fluid makes reverse the preceding statements with respect to a lighter fluid. The aforementioned findings shed light on the essential design keys that outstandingly affect the mechanics of the GPL pipe conveying pulsating fluid that lead and conduct forthcoming studies and open new horizons for designers in industry implementations.