Parachute design is challenging to achieve innovative progress if the dominant role of testing continues, as it will be an increasingly expensive and time-consuming work. The aim of this study is to establish a reliable and efficient design tool using existing advanced numerical modeling methods. This paper presents a numerical method based on two-way coupled fluid-structure interaction (FSI) strategies

The hubless rim-driven thruster (RDT) has become increasingly interesting for ship propulsion. Gap flow has been proven as the main feature of RDT that cannot be simply neglected. In this study, based on a classical hubless RDT, the effects of the gap geometry are studied by adjusting its axial passage length, and inlet and outlet oblique angles. The hydrodynamic characteristics of the RDT were simulated

The dynamic characteristics of running away pump turbines (PTs) with a large head variable amplitude have not been understood thus far, primarily because of two difficulties in simulation and analysis. The first is how to provide accurate time-varying boundary conditions for transient simulation of the turbine runaway process (TRP). The other is how to determine the specific appearance time of each

This study enlightens the magnetohydrodynamic Jeffery-Hamel flow under an inclined Lorentz force through a non-uniform conduit having slip at walls, which is frequently applied in geothermal applications, electronic cooling devices, and modern energy systems, etc. Therefore, the performance of a two-dimensional purely radial flow inside a converging-diverging channel is explored from the perspective

Enhanced understanding of turbulent flow structure in bends in natural rivers is essential for waterway regulation, navigation safety and environmental and ecological wellbeing. However, the flow structure in consecutive bends has so far remained poorly understood, especially when it is subject to the influence of tributary inflow. Here, the 3D flow structure in two consecutive bends, namely Qigongling

The current mixers in the compressed air foam system used to generate liquid foam have high flow resistance. Kenics static mixer may be a better choice for making foam because its spiral structure can lower the flow resistance. However, the effects of the structure of Kenics static mixer on the properties of liquid foam remain unclear. The primary objective of this work is to study the influences of

A multiphase flowmeter (MPFM) is used in the upstream oil and gas industry for continuous, in-line, real-time, oil-gas-water flow measurement without fluid separation. An MPFM typically consists of phase-fraction and velocity measurements. It is desirable to have homogeneous flow at the measurement location so that the phase-fraction measurement is representative. A horizontal blind-tee pipe-section

Precisely forecasting air temperature as a significant meteorological parameter has a critical role in environment quality management. Hence, this study employs a hybrid intelligent model for accurately monthly temperature forecasting for one to three times ahead in the hottest and coldest regions of the world. The hybrid model contains the artificial neural network (ANN) hybridized with the powerful

Since the proposal of inertial microfluidics in 2007, it has been widely used for particle focusing and separation with superior performances. The particle migration behaviour in microchannel is extremely complicated involving various parameters. Recently, computational approaches have been utilized to obtain better insights into the underlying physics, which facilitates a comprehensive and intuitive

High-velocity aerated flow is a common phenomenon in spillways. Its accurate modelling is challenging, mainly due to the lack of realistic physics in the conventional two-phase models. To this end, this study establishes a population balance model (PBM) approach to account for the evolutionary process of air bubbles. The air-water flow in a stepped chute is examined. The model performance is evaluated

To examine the cavitation noise characteristics of centrifugal pumps, the combination of test and simulation was applied in this study. The numerical method is based on spherical cavity radiation theory and the acoustic finite element method. A multi-field synchronized test-rig was built to study and validate the numerical results under cavitating flow and cavitation noise conditions. The three-dimensional

ABSTRACT Smoothed Particle Hydrodynamics (SPH) method is used to solve water hammer equations for pipeline systems due to its potential advantages of easily capturing column separation and slug impact. Currently, the SPH-based water hammer model has been only developed to simulate single pipe flow with simple boundary conditions. It is still a challenge to apply the SPH-based water hammer model to

Recent technological advances have made it possible to produce particles with nanometer dimensions that are uniformly and steadily suspended in traditional solar liquids and have enhanced the impact of thermo-physical parameters. In this research, a three-dimensional flat plate solar collector was built using a thin flat plate and a single working fluid pipe. The physical model was solved computationally

The flat-plate solar collector (FPSC) three-dimensional (3D) model was used to numerically evaluate the energy and economic estimates. A laminar flow with 500 ≤ Re ≤ 1900, an inlet temperature of 293 K, and a solar flux of 1000 W/m2 were assumed the operating conditions. Two mono nanofluids, CuO-DW and Cu-DW, were tested with different shapes (Spherical, Cylindrical, Platelets, and Blades) and different

In the present study, a computational methodology based on computational fluid dynamics (CFD) is developed to investigate free surface film flow and its subsequent disintegration on a rotary disk atomizer. The present study provides an insight into efficiently modeling both liquid film formation and its subsequent disintegration. The presented computational methodology can easily be reproduced and

ABSTRACT The motion response of a ship in a cross sea is studied based on computational fluid dynamics. Firstly, according to the established numerical pool, and based on the Reynolds-averaged Navier–Stokes equations and the re-normalisation group K–ϵ turbulence model, the free surface is treated by the volume of fluid(VOF) method, and a numerical simulation method is established. The wave results

This paper proposes a leak detection and size identification technique in fluid pipelines based on a new leak-sensitive feature called the vulnerability index (VI) and 1-D convolutional neural network (1D-CNN). The acoustic emission hit (AEH) features can differentiate between normal and leak operating conditions of the pipeline. However, the multiple sources of acoustic emission hits, such as fluid

Precessing vortex rope (PVR) plays a key role in inducing hydraulic resonance in Francis turbines operating at partial load, possibly degrading power plant stability and availability. Air injection into the runner cone is a suitable mitigating alternative; however, the influence mechanism of air injection on PVR remains unclear. The principal objective of this study was to establish response relationships

Flow conditioners are widely utilized in pipeline systems to improve the precision of flow rate measurement in the pipeline systems of the offshore and subsea oil and gas industry. There is a lack of knowledge about the influences of the conditioners on the flow inside a bend pipe due to the measurement inaccuracy caused by geometries complexity. In this study, numerical simulations are carried out

Supercavitation has been recently presented as an effective method for the drag reduction of underwater vehicles. However, maintaining the supercavitating state requires a lot of energy, making vehicles difficult to control. Therefore, it is necessary to design an underwater vehicle with low drag in the fully wetted state while being able to move at ultra-high speed in the supercavitating state. In

In the paper, the modulation effect of rotor-stator interaction subjected to fluctuating rotation speed is investigated numerically. A quasi-bivariate variable mode decomposition method for analyzing non-stationary flow fields is proposed for the first time. Different from the previous studies, this paper emphasizes the local features of the transient flow field at fluctuating rotation speed. The results

ABSTRACT This paper put forward a new fully discrete scheme construction method – double entropy condition solution formula method. With that, we turn the state-of-the-art semi-discrete WENO + RK scheme into a fully discrete scheme, which is named as Full-WENO. A major difficulty of this work is that we lack exact solution expressions for nonlinear equations in general cases. A feasible way we can

Handling a large number of geometric constraints brings a big challenge to the surrogate-based aerodynamic shape optimization (ASO) driven by computational fluid dynamics (CFD). It is not feasible to calculate the geometric constraint functions directly during the sub-optimization of a surrogate-based optimization, as the geometric constraint functions are to be evaluated thousands of times for each

ABSTRACT Inspired by the natural bifurcating structures, tree-like microchannels have been applied for microelectronics cooling. In order to understand the thermal-hydraulic performance of a flat-plat tree-like microchannel, successive branching ratios of tree-like structure are optimized based on minimization of flow resistance. It is shown that the optimal successive diameter ratio of symmetrical

Vortex generator (VG) is one of the potential technical tools to reduce the aerodynamic resistance of high-speed trains. The passive control resistance reduction research of a high-speed train is carried out by using VG. Three typical installation locations, including flow separation point, boundary layer mutation and streamline transition location, and several nearby locations were selected to study

Accurate inflow turbulence wind profile is a key premise of large eddy simulation (LES) methodology for super tall buildings. This paper presents an improved method for narrow band synthesis random flow generation to produce a more accurate inflow turbulence of LES based on superposition of harmonics. The proposed method considers time correlation by adopting time parameters, and an accurate expression

The radial flow field structure, which has the advantages of low pressure drop, good water removal and good mass transfer, is an emerging structure for proton exchange membrane fuel cell (PEMFC) flow fields. However, optimization work on the design the structure is scarce for a complex structure that is difficult to manufacture. A comprehensive three-dimensional, non-isothermal and single-phase mathematical

Air-core vortices are a ubiquitous phenomenon in the intakes of hydropower stations. Due to the transient and instability of two-phase vorticial flow, the prediction of air-core vortex formation is challenging, and understanding of the instability mechanism remains elusive. In this study, the large eddy simulation (LES) method and a coupled level-set and volume-of-fluid (CLSVOF) method are performed

This numerical study investigated a single air jet impingement at a constant temperature. Different RANS turbulence models, namely the v2-f model and four Reynolds stress turbulence models (the linear pressure-strain model, the quadratic pressure-strain model, the stress-omega model and the stress-BSL model) were employed to simulate and compare the numerical results with other published measurement

Bilateral vertical noise barriers have been widely used along high-speed railway lines in coastal cities where typhoons are frequent. When a high-speed train (HST) enters (or exits) a noise barrier under strong crosswind conditions, its running safety will be more severely tested because of the instantaneous switching of aerodynamic environment. Installing a buffer structure at the end of the noise

During the operation of supercritical CO 2 (sCO 2) radial inflow turbines (RITs), sonic conditions may happen, which will decrease their efficiency. Non-standard design geometries are needed to reduce the losses. However, modifying the turbine geometry is a challenge, especially as the optimum shape may be non-intuitive; commercial computational fluid dynamics (CFD) software is not friendly towards

It is important to reduce carbon emissions caused by the energy consumption of pumps. This study used a centrifugal pump with a specific speed of 89.6 as the research object to improve pump efficiency. The adaptive single-objective method was adopted as the automatic optimization tool with computational fluid dynamics, which includes optimal space-filling experimental design, Kriging response surface

Tidal energy is one of the world's most predicable renewable energy sources and therefore holds great potential to be a valuable building block for the decarbonisation of electricity production. This paper focuses on a Venturi shaped duct structure (shroud) to accelerate the flow speed at a vertical axis tidal turbine utilising the low static pressure created at the exit of the shroud. This concept

ABSTRACT Accurate estimation of the longitudinal dispersion coefficient (LDC) is essential for modeling the pollution status in rivers. This research investigates the capabilities of machine-learning methods such as multi-layer perceptron (MLP), multi-layer perceptron trained with particle swarm optimization (MLP-PSO), multi-layer perceptron trained with Stochastic gradient descent deep learning (MLP-SGD)

ABSTRACT A major drainage systemwhich uses urban roadways as flood passages during extreme storm events has been proven to be effective and low-cost. However, to date, the amount of flow diverted at a bifurcating road crossing still could not be accurately assessed. Previous studies mainly focused on diversion flat bottom channels with no turning radius. Results from these studies are not applicable

The fixed scroll of the scroll compressor is usually immovable, and the deformation of the scrolls may lead to the operation stuck, which may be avoided by designing the fixed scroll as floating one. However, the introduction of floating fixed scroll will inevitably cause the variation of the dynamic characteristics, so it is necessary to establish a simulation model to explore the influence of floating

Due to the complicated geometric shape, it's difficult to precisely obtain the aerodynamic force of high-speed trains. Taking numerical and experimental data as the training data, the present work proposed a data-driven rapid prediction model to solve this problem, which utilized the Support Vector Machine (SVM) model to construct a nonlinear implicit mapping between design variables and aerodynamic

How to accurately predict the resonance operating point and the corresponding vibrating amplitude of the underwater structures are of interest in the field of hydraulic machinery. In the present investigation, a resonance risk assessment method consisting of unsteady CFD, modal work approach, and harmonic response analysis is established, and an implementation is carried out on a centrifugal impeller

ABSTRACT The aerodynamic drag of pantograph system hinders the increase of train operating speed, which can be reduced by the covering structure proposed in this study. Exploring the drag reduction mechanism of covering structure is critical. An IDDES method based on the SST κ–ω turbulence model was utilized to study the effect of covering structure on aerodynamic performance of high-speed train. The

In this paper, the simulation and modeling of the turbulent atmospheric boundary layers (ABLs) in the presence of forests are studied using a lattice Boltzmann method with large eddy simulation, which was implemented in the open-source program GASCANS with the use of Graphic Processing Units (GPU). A method of modeling forests in the form of body forces injected near the wall is revisited, while the

An integrated slipper/swashplate structure is developed for seawater hydraulic axial piston pump. Considering the overturning moment of the integrated slipper, the transient hydrodynamic lubrication model of the integrated slipper is established, and the body-fitted grid and five-point finite difference method is employed to accurately solve the model. An optimization design method based on a hybrid

ABSTRACT In this study, numerical simulations and experiments were conducted on patient-specific normal abdominal aorta and abdominal aortic aneurysm (AAA) with intraluminal thrombus (ILT) models, which were reconstructed from computed tomography angiography (CTA) images published online. A scale-adaptive simulation (SAS) of the abdominal aortic aneurysm with a posterior eccentric thrombus was performed

For a combustion-based thermophotovoltaic generator (TPV), the baffle-induced reacting flows are numerically investigated in the micro combustor with a multihole baffle representing a mixed feature of bluff body and multiple jets. The lobed flow feature is realized by the momentum difference between fuel and air streams and the baffle wall, not the geometrical conditions like a lobed nozzle. Compared

Stent intervention is a recommended therapy to reduce the pressure gradient and restore blood flow for patients with coarctation of the aorta (CoA). A remaining challenge for physician is to select the optimal stent before treatment. Here, we propose a framework for personalized stent intervention in CoA using in silico modeling, combining image-based prediction of the aortic geometry after stent intervention

This study investigates the effect of aspect ratios (Ra*) on the wake bi-stability behind the GTS model using improved delayed-detached eddy simulation (IDDES) at a Reynolds number of 2.7×104. Eight cases with Ra* in the range of Ra*∈[0.5, 2.0] have been considered to investigate the asymmetric wake flow and the corresponding aerodynamic response. The primary objective of this study is to reveal the

Solar power integration in electrical grids is complicated due to dependence on volatile weather conditions. To address this issue, continuous research and development is required to determine the best machine learning (ML) algorithm for PV solar power output forecasting. Existing studies have established the superiority of the artificial neural network (ANN) and random forest (RF) algorithms in this

To broaden the efficient operating zone and increase the energy efficiency of a multi-stage double-suction centrifugal pump, a multi-component and multi-condition optimization design method involving high-precision performance predictions, a flow loss visualization technique based on entropy production theory, and machine learning is proposed. First, the accuracy of the baseline pump numerical methodology

ABSTRACT Due to frequent drought events, increased water demand for agricultural production and limited, accurate estimation of reference evapotranspiration (ETo) is necessary for developing crop irrigation schemes and rational allocation of regional water resources. The extreme learning machine (ELM) was optimized using four biological heuristic algorithms, namely, Grey Wolf Optimizer (GWO-ELM), Moth-Flame

Blockages are commonly formed in fluid pipelines such as water supply systems, which may greatly affect the internal flow states and conveyance capacities. This paper investigates the transient behavior of a pressured water pipeline with blockage under different transient wave perturbations based on the Computational Fluid Dynamics (CFD) model. To this end, a water pipeline is modeled in a 2D axisymmetric

ABSTRACT This study focuses on the correlative mechanism of the ambient pressure and inflow uniformity on the vortex and cavitation dynamics of an axial flow pump. The shear stress transport k – ω turbulence model and Schnerr–Sauer cavitation model are applied in the unsteady detached eddy simulation. The results show that the vortex merging between the primary and secondary tip leakage vortices (TLV)

Suspended sediment load (SSL) is essential to river and dam engineering. Due to the complexity and stochastic nature of sedimentation, SSL prediction is a challenging task and conventional methods often fail to generate accurate results. Aiming to provide an improved estimation, this paper contributes to a new forecasting framework by integrating the seasonal adjustment (SA) and Bayesian optimization

ABSTRACT In this research, a coupled numerical–experimental approach is employed to investigate the spray–wall interaction on step geometries with slope angles from 0° to 90° as well as impinging on and off the step geometry. Spray contours are used to compare the numerical and experimental results and, in general, good agreement between them is found. The results from the model are used to provide

ABSTRACT Two hybrid back-propagation neural network (BPNN) models optimized by two heuristic search algorithms, namely genetic algorithm (GA-BP) and particle swarm optimization (PSO-BP), are proposed in this paper to predict radial maximum wall shear stress instead of traditional computational fluid dynamics (CFD) methods. The two proposed models are trained and validated using a database of 150 radial

Due to the outstanding properties, magnetic particles have been widely used as magnetic carriers and adsorbents in a diverse range of fields, such as biomedical diagnostics, food safety, and environmental monitoring, etc. Sorting different magnetic particles from each other based on size simultaneously can be very useful in multiple targets separation. To the best of our knowledge, this research firstly

A lattice Boltzmann method (LBM) based on Shan-Chen pseudo-potential model is used to investigate the process of droplets merging and shedding on a gradient wetting circular surface. The effects of wetting gradient, radius, and radius ratio on droplet merging and shedding were mainly explored. The results show that applying a wetting gradient on the circumferential surface can accelerate the process

This paper presents an investigation on the compressible flow past spanwise wavy wings with an incoming flow of M∞=0.5 and Re=107. The scale adaptive simulation is employed here to solve the Favre-averaged equations. Three wings, with the ratio of wavelengths (λ) to chord length (c) respectively equaling to 1/2 (W4), 1/3 (W6), 1/4 (W8), are aerodynamically investigated. The aerodynamic force and separation

Aiming to investigate the transient four-quadrant hydrodynamics on blades under the circumferential motion of the steering center, an efficient three-dimensional (3D) model with half blades was established in this paper. The 3D model with half blades accounts for the hydrodynamic loss induced by the complicated mechanical structure, predicting the hydrodynamic performance of the high-load cycloidal

River streamflow is an essential hydrological parameters for optimal water resource management. This study investigates models used to estimate monthly time-series river streamflow data at two hydrological stations in the USA (Heise and Irwin on Snake River, Idaho). Five diverse types of machine learning (ML) model were tested, support vector machine-radial basis function (SVM-RBF), SVM-Polynomial

The evolution and characteristics of large-scale vortices are critical for understanding temporal and spatial exchange of mass and momentum. Using a validated depth-averaged large-eddy simulation (DA-LES) model, this paper visualizes the vortex processes in a partly-obstructed canopy channel, and analyzes associated hydrodynamics. Particular interests are focused on the effect of canopy blocking ratio

A transonic centrifugal compressor with a ruled-impeller (that is, impeller blades are generated by a set of points swept by a moving straight line) was used as the baseline, and the impeller blades were redesigned using non-ruled surfaces (referred to as the ‘free-form impeller’) in this study to reveal the potential of this design approach to improve the performance of high-pressure-ratio centrifugal