The hump formation mechanism has not been fully understood so far, mainly because of two difficulties in analysis. The first one is how to find the most important external characteristic factor inducing humps, and the other is how to avoid too many assumptions when analysing the change in the runner’s capacity for work (the direct use of Euler’s formula makes too many assumptions). This paper proposes

A bionic concept originating from the mechanism of gastric mucosa protecting a gastric wall from corrosion by gastric acid is creatively proposed, with the intention of finding a new way to reduce the corrosion of insulation coatings in liquid metal blankets. A compatible fluid barrier that mimics the function of gastric mucosa is used to prevent the flowing liquid metal from contacting the inner wall

In this study, we simulate the acceleration-induced cavity bubble expansion and its non-spherical collapse in a drastically varying pressure field caused by mechanical impact, and we qualitatively compare the results with those for similar ζ number (Obreschkow et al., 2011) as recorded by a high-speed camera (Taylor, 2012). The gas–liquid interface is tracked by using the volume of fluid method. The

This work evaluates the capabilities of Large Eddy Simulation with perfectly stirred reactor (PSR) assumption and detailed chemistry to predict unsteady, premixed, hydrogen combustion sequences. The model was benchmarked with hydrogen-air experimental tests and with numerical data of flame acceleration in an obstructed channel. Results permit to identify major shortcomings that should be addressed

ABSTRACT Microfluidic devices or systems to generate recirculating flow are increasingly utilized in the fields of chemistry, biomedicine, biology, with bottlenecks in integration and miniaturization needed a breakthrough. Here, a concept for a highly integrated valve-less piezoelectric micropump generating recirculating flow (VPMGRF) is proposed, simultaneously realizing innovation in theory and method

ABSTRACT Cross-flow turbines have recently been proposed for energy recovery in aqueducts when the outlet pressure is greater than zero, owing to their constructive simplicity and good efficiency within a large range of flow rates and head drops. In the case of high head drop (higher than 150 m) and relatively small discharge (lower than 0.2 m3/s), the traditional design of these turbines leads to

In the current study, a novel intelligent numerical computing paradigm based upon the foundation of the artificial neural networks legacy involving the Bayesian regularization (ANN-BR) approach has been implemented for the investigation of the non-uniform heat preoccupation process with the bio-convective flow dynamics of nanomaterial involving gyro-tactic microorganisms. The designed bio-convective

The diffusion of molecules in aqueous solutions in the domain of membrane technology is critical in the efficiency of chemical engineering and purification processes. In this study, the diffusion in high and low concentration regions is simulated with finite difference method (FDM), and then the results of numerical computations are coupled with adaptive network-based fuzzy inference system (ANFIS)

ABSTRACT Short-term hourly reliable prediction of significant wave height is an important research topic in coastal engineering. Many researchers have carried out in-depth studies in many ocean regions. Generally, most of this work is implemented through numerical models. However, as for numerical models, with the increase of hourly prediction duration, the accumulation of wave randomness leads to

This study proposes two techniques: Deep Learning (DL) and Ensemble Deep Learning (EDL) to predict groundwater level (GWL) for five wells in Malaysia. Two scenarios were proposed, scenario-1 (S1): GWL from 4 wells was used as inputs to predict the GWL in the fifth well and scenario-2 (S2): time series with lag time up to 20 days for all five wells. The results from S1 prove that the ensemble EDL generally

Future civil aircrafts require simple, low-noise, and highly efficient trailing-edge flaps. In this study, a detailed numerical study for flap improvements using steady and unsteady Reynolds-averaged Navier–Stokes computations was conducted. A movable trailing edge (MTE) was applied to the main element as a passive flow control method to improve the traditional Fowler flap. A new concept of a backward

The ship powering performance can be predicted based on model tests or simulations. However, differences exist between the full-scale ship performance and extrapolated model data. Therefore, research on full-scale ship performance simulation has important scientific significance and engineering value. This study used the REGAL general cargo vessel to perform full-scale ship resistance and self-propulsion

Accurate prediction of water level (WL) is essential for the optimal management of different water resource projects. The development of a reliable model for WL prediction remains a challenging task in water resources management. In this study, novel hybrid models, namely, Generalized Structure-Group Method of Data Handling (GS-GMDH) and Adaptive Neuro-Fuzzy Inference System with Fuzzy C-Means (ANFIS-FCM)

Among several indicators for river engineering sustainability, the longitudinal dispersion coefficient ( Kx) is the main parameter that defines the transport of pollutants in natural streams. Accurate estimation of Kx has been challenging for hydrologists due to the high stochasticity and non-linearity of this hydraulic-environmental parameter. This study presents a new hybrid machine learning (ML)

Research on turbulent drag reduction has been limited owing to the limitations of existing parameters used for the identification of vortex structures. As a new and more suitable vortex parameter, Liutex provides a novel research method for turbulence control. We used a channel with a transverse groove structure as the research model and employed large-eddy simulation method based on Liutex to study

Based on the analysis of the entropy condition scheme formulation, the accuracy order comes from initial value interpolation and flux reconstruction. Following the limiters of the traditional second-order Total Variation Diminishing scheme, higher accuracy order and non-oscillatory nature are retained with a newly proposed smoothness threshold method. Then, the scheme using the solution formula method

Inspired by the animal upper digestive tract, a unique soft-elastic reactor (SER) has recently been researched whose mixing phenomena should be further investigated. Numerical simulation is an excellent method with which to explore the phenomena in SERs for a large number of conditions. It may also offer insights into the ways of effective mixing in this kind of reactor. The mixing processes in 2D

Operation of heavy-duty machines leads to an observation that seals in hydraulic cylinders are frequently subjected to thermal degradation. The basis of this research is the previously proven thesis that the temperature of the liquid in the cylinder and the cylinder itself may significantly differ from the temperature of the liquid in the system and in the tank, thus enabling the temperature in the

In biodiesel production by trans-esterification, one of the essential compound is glycerin. Global glycerin production is increasing significantly, projecting a global value reduction for glycerol. Consequently the scientific community had been encouraged to investigate converting glycerol into more valuable products. In this research, the primary sources and processes of biodiesel production are surveyed

The idea of using the compact device with higher heat transfer potential has encouraged researchers to use microchannels. Creating sinusoidal walls is a technique leading to better effectiveness and smaller size. In this study, the effects of discrete heat sources location on heat transfer and pressure drop are investigated, using graphene nanoplatelets/water inside a sinusoidal microchannel. For this

Owing to the importance of municipal waste as a determining factor in waste management, developing data-driven models in waste generation data is essential. In the current study, solid waste generation is taken as the function of several parameters, namely month, rainfall, maximum temperature, average temperature, population, household size, educated man, educated women, and income. Two different stand-alone

Utilizing new approaches to accurately predict groundwater level (GWL) in arid regions is of vital importance. In this study, support vector regression (SVR), Gaussian process regression (GPR), and their combination with wavelet transformation (named wavelet-support vector regression (W-SVR) and wavelet-Gaussian process regression (W-GPR)) are used to forecast groundwater level in Semnan plain (arid

The liquid rocket propellant burns inadequately in the combustion chamber; therefore, the exhaust gas reacts with oxygen and the heat that was generated, which in turn affects the thermal environment. By using finite-rate chemical kinetics and discrete ordinates method, the calculation model for the four-engine rocket exhaust flowfield is established, and numerically investigates the afterburning effect

This paper proposes a bio-inspired hull shape (BHS) for AUV by studying and modeling the body shape of humpback whales. Among factors affecting hydrodynamic characteristics, this paper considers both the hull drag and displacement volume to optimize the BHS, which profitably improve the space utilization and voyage of the AUV. The optimization is conducted by a surrogate model using response surface

Ensuring accurate estimation of evaporation is weighty for effective planning and judicious management of available water resources for agricultural practices. Thus, this work enhances the potential of support vector regression (SVR) optimized with a novel nature-inspired algorithm, namely, Slap Swarm Algorithm (SVR-SSA) against Whale Optimization Algorithm (SVR-WOA), Multi-Verse Optimizer (SVR-MVO)

This paper reports on the derivation and implementation of a shape optimization procedure for the minimization of hemolysis induction in blood flows through biomedical devices.Despite the significant progress in relevant experimental studies, the ever-growing advances in computational science have made computational fluid dynamics an indispensable tool for the design of biomedical devices. However

To investigate the seismic performance of a wind turbine that is influenced by both the ice load and the seismic load, the research proposes a numerical approach for simulating the seismic behavior of a wind turbine on a monopile foundation. First, the fluid–solid coupled equation for the water–ice–wind turbine is simplified by assigning reasonable boundary conditions and solving the motion equation

Vortex is the dominant flow structure in hydro-energy machinery, and its swirling features are mainly determined by the rigid rotation part of vorticity. In this study, the rigid vorticity transport equation is proposed based on the vorticity decomposition. The vortex spatial evolution is described by the stretching term RST, the dilatation term RDT, the Lamb term RCT and the viscous term RVT. The

This work computationally explores the two-phase flow of nanofluids and their thermal energy transport coefficients in 3D diamond-shaped cavities with square-shaped barriers having reducing dimensions. Materials with two emissivity values, ϵ=0.3 and 0.9, have been considered to investigate the effect of the radiation thermal energy transport coefficient while the hot side is maintained at 400 or 500 K

This research aims to estimate the overflow capacity of a curved labyrinth using different intelligent prediction models, namely the adaptive neural-fuzzy inference system, the support vector machine, the M5 model tree, the least-squares support vector machine and the least-squares support vector machine–bat algorithm (LSSVM-BA). A total of 355 empirical data for 6 different congressional overflow

This paper studies the interaction of two droplets splashing on a stationary film. A source term is included in the large-density-ratio pseudopotential lattice Boltzmann method to achieve tuneable surface tension. This model offers excellent numerical accuracy and stability for droplet impacts on liquid films. The influence of the Reynolds number, Weber number, film thickness, and horizontal/vertical

ABSTRACT The magnetically assisted resistance spot welding (MA-RSW) method provides a promising approach for improving weld performance. However, the MA-RSW process involves complex multiphysics fields that make numerical modeling very challenging. Thus, most resistance spot welding (RSW) models adopt electrothermal-mechanical coupling and ignore the influence of fluid flows caused by electromagnetic

Cage-type control valves are widely used in process industries, but cavitation can occur when the valves are used in extreme high-pressure drop and large volume flow rate conditions. In this study, the cage-type control valve with improved valve cages is introduced, and its flow and cavitation characteristics are compared with other cage-type control valves with no dead zones in the regulation process

With airborne transmissions found as one of the major transmission routes of SARS-CoV-2, its transmission in airliner cabin environments drew special attention due to high number of imported cases and in-cabin transmissions. This study numerically investigated the transmission of COVID-19 by cough-induced particles in a cabin section of Boeing 737 model. One passenger was coughing in each case, while

This study compares several advanced machine learning models to obtain the most accurate method for predicting the aeration efficiency (E20) through the Parshall flume. The required dataset is obtained from the laboratory tests using different flumes fabricated in National Institute Technology Kurukshetra, India. Besides, the potential of K Nearest Neighbor (KNN), Random Forest Regression (RFR), and

To accurately predict tropospheric ozone concentration(O3), it is needed to investigate the variety of artificial intelligence techniques’ performance, such as machine learning, deep learning and hybrid models. This research aims to effectively predict the hourly ozone trend via fewer input variables. This ozone prediction attempt is performed on diversity data of air pollutants (NO2, NOx, CO, SO2)

An optimization method of structure parameters based on the quadratic regression orthogonal combination (QROC) and Genetic Algorithm (GA) is proposed in this work. The following work has been conducted to improve the performance of the coal pyrolysis filtration system and prolong the service life of the filter tubes based on QROC-GA method. Firstly, a simulation model is established and two factors

We investigated the effects of atherosclerosis in the carotid region on cerebral haemodynamics. A total of 15 stenosis cases following NASCET criteria were modelled using patient-specific medical image data and an open-source package, SimVascular. The formulation adopted the stabilised Petrov–Galerkin scheme with Newtonian and incompressible assumptions. The boundary conditions employed pulsatile inflow

The present work investigates heat transfer through natural convection using a series of experiments and computational modeling using Computational Fluid Dynamics (CFD) simulations in a one-meter bundle pipe with three internal pipes. The exact complex geometry is modeled where the flow channel is reduced through a spiral groove attached to a rod inside the internal tubes which was challenging compared

A dynamical system involving the decaying test of a partially filled liquid tank is analyzed in the present paper. This analysis is relevant for the design of aircraft fuel tanks, where the wings' structural dynamics are influenced by the complexity and the violence of the internal flow generated when atmospheric turbulence or gust is encountered. The study of this kind of system is performed in order

Porous wind barriers (PWBs) are gradually applied to tunnel–bridge–tunnel infrastructures (TBTIs) along high-speed railway lines. Due to the remarkable aerodynamic effect of high-speed trains (HSTs), the windproof performance of a PWB at tunnel–bridge section (TBS) is particularly critical when a HST passes through the TBTI under crosswind. And it seems to be easily ignored by researchers. This study

The ship hull form optimization using the Computational Fluid Dynamics (CFD) method is increasingly employed in the early design of a ship, as an optimal ship hull form can obtain good hydrodynamics. However, it is time-consuming due to its many CFD simulations for the optimization. This paper presents a ship hull form optimization loop using the surrogate model, deep belief network (DBN), to reduce

Lubrication and cooling performances of face gears with oil–jet lubrication are closely related to the nozzle layouts. To investigate the influence of the nozzle layouts on the lubrication performance of the face gears, a numerical analysis method based on heat-flow coupling is adopted in this study for predicting the transient temperature characteristics. First, a mathematical model of impingement

Turbine guide vane faces extremely high thermal load, especially on the leading edge region. In order to enhance cooling performance, the present study investigates the effects of leading-edge film cooling arrangements by adiabatic and aero-thermal coupled simulation. The three-row cooling design of the 25° inclined angle with the trenched holes is used to replace five-row showerhead holes. The SSTk−ωγ−Reθ

This study numerically investigates the combustion characteristics in a swirl burner for CO-H2 syngas by large eddy simulation. Firstly, experimental data are used to verify the applicability of the Boivin mechanism and the Sandia mechanism. The simulation results show that the Boivin mechanism predicts a more reasonable flame structure. Then, Syngas25, Syngas45, and Syngas100 (composed of 25%, 45%

This paper aims at ensuring the safety of catenary operation, by considering the flow field characteristics of the specific railway terrain and the wind-induced dispalcement of the catanery contact wires. Combining fluid and structure analyses, the improved delayed detached eddy simulation (IDDES) method based on the κ-ω turbulence model was used to explore the flow field characteristics at the position

In this study, a computational fluid dynamics approach based on solving the Reynolds-averaged Navier-Stokes equation and shear stress transport (SST) (Menter) k-ω turbulence model is used to solve the rotor in ground effect. A discrete element method based on solving the Hertz-Mindlin (no-slip) contact model and considering the real physical properties and collision is used to solve the motion and

Gaseous and vaporous cavitation have extremely harmful effects on hydraulic axial plunger pumps, reducing flowrate and increasing flow pulsation. The collapse of vapor bubbles strongly impacts the inner wall and produces many pits. Therefore, it is very important to reduce gaseous and vaporous cavitation to improve the performance of hydraulic axial plunger pumps. In this work, a full cavitation model

ABSTRACT Complex two-phase flow phenomena in wellbores after sour gas kick may lead to severe well control incidents. By bridging the gas solubility, H2S phase transition and flow equations, a two-phase flow model is established under conditions of transient and non-isothermal states in wellbores, which is well validated against the two-phase flow experimental data. The following conclusions are drawn

ABSTRACT Sediment transport in the ejector is highly stochastic and non-linear in nature, and its accurate estimation is a complex and challenging mission. This study attempts to investigate the sediment removal estimation of sediment ejector using newly developed hybrid data-intelligence models. The proposed models are based on the hybridization of adaptive neuro-fuzzy inference systems (ANFIS) with

The evaporation-driven motion and deposition dynamics of nanoparticles (NPs) play significant roles in inkjet-printed structures such as the finger electrodes of solar cells. The objective of the present work is to reveal the mechanisms of NPs motion and distribution on a textured surface in the multi-droplets impact, coalescence and evaporation process. However, the complex interplay among NPs, host

The MENA-CORDEX (the Middle East and North Africa-COordinated Regional Downscaling Experiment) wind speed data at the height of 10 m is converted to the turbine hub-height for estimating the mean wind power in the Gulf of Oman. The results show high spatial variability of the historical and future mean wind power projection. Furthermore, the impact of climate change on the mean wind power (under the

The propeller wake can cause vibrations on the rudder surface, which worsen the noise and reliability. The vibration monitoring of the rudder operating in the propeller wake with fluid-structure interaction (FSI) method is still challenging. In the present study, the structural response during propeller-rudder interaction is investigated using detached eddy simulation. Three-dimensional distributions

Double-unit trains increase passenger capacity but also increase energy consumption. Therefore, research about the aerodynamic resistance of a double-unit train is of great importance to save energy. In this study, a commercial long-marshalling high-speed train and 8 kinds of double-unit trains are used to investigate the effect of the gap length on aerodynamic resistance. The results show that the

Design optimization of transonic airfoils for rotary blades is a challenging subject that remarkably affects the stage and overall performance of axial-flow compressors. This paper describes a surrogate-based multi-objective optimization process over a transonic rotary blade. This blade works in the first high-pressure stage of a pre-designed industrial axial compressor. It experiences a massive separation

ABSTRACT The turbulent convective thermal transfer in channel heat exchangers (CHEs) is studied numerically via the CFD (Computational Fluid Dynamics) method. Deflectors are inserted on the hot bottom walls of the heat channel to enhance the hydrothermal characteristics. Various shapes of in-line deflectors are considered, namely: rectangular (a/b = 0.00), cascaded rectangular-triangular (a/b = 0.25

ABSTRACT Rivers in the north-western region of China have a high sediment content, and the construction of reservoirs on these rivers must address the problem of sedimentation that results in a loss of reservoir capacity. In this study, the YZD (Yazidang) reservoir was considered as a typical case, to address the problem of sedimentation in injection-type water supply reservoirs in Northwest China

This paper presents a coupled heat transfer model for coal-fired boilers that integrates boiler’s fire side computational fluid dynamics (CFD) solution with the boiler’s steam cycle, and thus, can predict the boiler steam temperatures subject to different boiler design and operation conditions. In this coupled model, the heat transfer submodels describing the gas-steam heat exchange for each part of

It is important to optimize the structure of inlet due to the increasing demand of ram air. In this paper, structural optimization of the submerged inlet is pursued using a hybrid model by integrating least squares support vector machines (LS-SVM) prediction model and improved genetic algorithm-particle swarm optimization (GA-PSO). Inlet shape is controlled by changing three-dimensional geometric parameters

ABSTRACT In this study, the unique reverse-flow around the inlet nozzle of a squirrel-cage fan was numerically studied by computational fluid dynamics (CFD), and a non-axisymmetric D-type inlet nozzle was proposed to inhibit it. It is shown that serious back flow develops at the volute tongue when the fan operates at a low flow coefficient that is lower than the best efficiency point. The airflow passing