The tubeless vortex reducer was used to reduce the pressure drop in a cavity with radial inflow. In previous studies, the mechanism of vortex breakdown in tubeless vortex reducers was not clear, and there was a lack of direct guidance for engineering design. In this paper, we studied the vortex and pressure in the cavity in detail by large-eddy simulation (LES) and experiments. A mathematical model

Purpose The purpose of this study is to investigate the two-dimensional unsteady inclined stagnation point flow and thermal transmission of Maxwell fluid on oscillating stretched/contracted plates. First, based on the momentum equation at infinity, pressure field is modified by solving first-order differential equation. Meanwhile, thermal relaxation characteristic of fluid is described by Cattaneo–Christov

To investigate the hard-to-measure complex flow in a squirrel-cage fan, a slice model was established in the present study to perform a partial large eddy simulation calculations on an r-θ sectional flow field instead of the large-scale and time-consuming full three-dimensional flow calculations. The method used to build the slice model was first introduced, and then the model was verified by the results

Purpose The purpose of this paper is to analyze the heat and momentum transfer for steady two-dimensional incompressible nanofluid flow through a wavy channel with linearly varying amplitude in the entrance region. Design/methodology/approach The mass, momentum and energy conservation equations for laminar flow of Cu-water nanofluids are computationally solved using the finite element method. A parametric

Purpose The purpose of this paper is to identify freezing in pitot tubes at real-time, by means of the estimated heat transfer coefficient (HTC) at the tip of the probe. The prompt identification of such freezing is paramount to activate and control mechanisms for ice removal, which in turn are essential for the safety of the aircraft and its passengers. Design/methodology/approach The proposed problem

Purpose This paper aims to deal with the heat transmission of Sutterby fluid-containing gyrotactic microorganism by incorporating non-Darcy resistance law. The mathematical modeling is based on nanoparticle concentration, energy, momentum and motile microorganism equations. Design/methodology/approach The governing nonlinear coupled equations are first rendered into nonlinear ordinary equations using

Purpose This study aims to investigate lattice Boltzmann (LB) simulation of the fluid flow and heat transfer characteristics of a heated porous elliptic cylinder in uniform flow based on the two-domain scheme. In the present research, the effect of axis ratio (1 ≤ AR ≤ 2), Reynolds number (5 ≤ Re ≤ 40) and Darcy number (10−4 ≤ Da ≤ 10−2) are studied. Design/methodology/approach To perform the LB simulation

Purpose The purpose of this paper is to analyze numerically forced convective conjugate heat transfer characteristics for laminar flow through a wavy minichannel. Design/methodology/approach The mass and momentum conservation equations for the flow of water in the fluidic domain and the coupled energy conservation equations in both the fluid and solid domain are solved numerically using the finite

The wind resistance of a model of a large container ship was investigated experimentally and numerically under various conditions to investigate the aerodynamic performance and identify approaches for reducing wind resistance. The container ship model with and without six types of forecastle fairing was tested in a wind tunnel under conditions of full load and various uneven loads in different wind

The hydraulic joint is the key driving component of a robot. To reduce the joint size of the hydraulic robot, and improve the control accuracy and dynamic response performance, this paper proposes a novel joint structure and control method of a ball double-screw hydraulic robot. Using ball and circular arc spiral groove transmission, the hydraulic joint has a small transmission friction coefficient

Purpose The purpose of this paper is to experimentally and numerically investigate the cooling performance of the air-to-water thermoelectric cooling system under different working conditions. Design/methodology/approach An air-to-water thermoelectric cooling system was designed and manufactured according to the principle of discrete binary thermoelectric Peltier modules, and the thermal performance

Purpose Thus, the purposes of this study are to study the limits of applicability of the self-similar solution to the problem of fluid flow, heat and mass transfer in conical gaps with small conicity angles, to substantiate the impossibility of using a self-similar formulation of the problem in the case of large conicity angles and to substantiate the absence of the need to take into account the radial

A gas journal microbearing and the corresponding rotor-bearing system are studied both theoretically and experimentally for their application in the high-speed air compressor of fuel cell vehicles. The gas microbearing is proved to provide reliable support for the rotor, as it shows both static and dynamic pressure effects under the high operating speed of the on-board air compressor. In order to realize

In pursuit of stable operation in thermal hydraulic engineering, this paper researches two-phase flow through tube bundles by the lattice Boltzmann method. The single-relaxation-time lattice Boltzmann model and the multicomponent, multiphase pseudo-potential lattice Boltzmann model are adopted. Specifically, the two-phase flow past double-tandem circular cylinders, double-parallel circular cylinders

Purpose The purpose of this paper is to thoroughly investigate the aerodynamic effects of blade pitch angle on small scaled horizontal axis wind turbines (HAWTs) using computational fluid dynamics (CFD) method to find out the sophisticated effects on the flow phenomena and power performance. Design/methodology/approach A small HAWT is used as a reference to validate the model and examine the aerodynamic

The suspended sediment load (SSL) is one of the major hydrological processes affecting the sustainability of river planning and management. Moreover, sediments have a significant impact on dam operation and reservoir capacity. To this end, reliable and applicable models are required to compute and classify the SSL in rivers. The application of machine learning models has become common to solve complex

Purpose This paper aims to examine the squeezing flow of hybrid nanofluid within the two parallel disks. The 50:50% water–ethylene glycol mixture is used as a base fluid to prepare Ag–Fe_3O_4 hybrid nanofluid. Entropy generation analysis is examined by using the second law of thermodynamics, and Darcy’s modal involves estimating the behavior of a porous medium. The influences of Viscous dissipation

Purpose The boundary integral method (BIM) provides unparalleled computational efficiency for solving problems wherever it is applicable. For Stokes flows, the BIM in its current form can only be applied to a limited class of problems that generally comprises boundaries with either specified velocity or stress. This study aims to radically extend the applicability by developing a general method within

Purpose Stent malapposition is one of the most significant precursors of stent thrombosis and restenosis. Adverse haemodynamics may play a key role in establishing these diseases, although numerical studies have used idealised drug transport models to show that drug transport from malapposed drug-eluting stent struts can be significant. This paper aims to study whether drug transport from malapposed

Particles and condensing vapors contribute to the contamination of optical components of solar thermochemical reactors including windows and secondary concentrators and result in severe reactor performance deterioration. We propose an impinging-jet solar reactor in a distinctive topology to enhance aerodynamic-aided window protection. The vector fields on the two-dimensional inner surfaces of the impinging-jet

Purpose The purpose of this paper is to analyse the buoyancy flow, mass and heat transfer in coaxial duct under Soret and Dufour effect. The combined effects of the thermal-diffusion and diffusion-thermo coefficients, as well as the Schmidt number, on natural convection in a heated lower coaxial curve were explored using the proposed physical model. The Dufour and Soret effects are taken into consideration

Swirling gas flow is an important topic of research that helps in the design of rockets, atomizers,and gas turbine combustors. In the present work, swirl flow inside annular geometries with constant and varying cross-sectional areas are examined using computational fluid dynamics (CFD). Effects of changing the flow and geometric parameters on the swirl behaviour were studied. Reynolds number was found

The launch vehicle will experience extreme acoustic environment at lift-off, which will cause the invalidation and destruction of the aerospace equipment, and reducing noise is of great significance for improving launch safety. In this paper, the numerical simulation of gas–liquid two-phase flow and its acoustic field is carried out, and the flow field is simulated by the discrete phase model (DPM)

Purpose This study aims to perform flow simulations inside the acinus with fine alveolar pores (Kohn pores) using hexagonal cells and bottom-up geometric modeling, which enabled the elimination of invalid voids using previous top-bottom methods and spherical or circular cells. Design/methodology/approach Regular hexagonal cells were used to construct alveoli with no gaps via tessellation. Some hexagonal

Purpose The Fay and Riddell (F–R) formula is an empirical equation for estimating the stagnation-point heat flux on noncatalytic and fully catalytic surfaces, based on an assumption of equilibrium. Because of its simplicity, the F–R has been used extensively for reentry flight design as well as ground test facility applications. This study aims to investigate the uncertainties of the F-R formula by

Purpose This paper aims to propose a semi-analytical benchmarking framework for enthalpy-based methods used in problems involving phase change with latent heat. The benchmark is based on a class of semi-analytical solutions of spatially symmetric Stefan problems in an arbitrary spatial dimension. Via a public repository this study provides a finite element numerical code based on the FEniCS computational

Most mixed-flow pumps obtain a saddle-like Q-P curve with a backflow, owing to the increased incidence angle at low flow rates. The backflow was developed near the shroud and followed downstream again at its end to form a recirculating flow. The rotating stall, which could be a part of the recirculating flow, followed the impeller’s rotational direction, and its properties affected the local stability

Purpose This study deals with the computational simulation and inverse analysis of the cooling treatment of the hypoxic-ischemic encephalopathy in neonates. A reduced-order model is implemented for real-time monitoring of the internal body temperatures. The purpose of this study is to sequentially estimate the transient temperatures of the brain and other body regions with reduced uncertainties. D

Dropshafts with tangential intakes are common structures in urban water drainage systems. The plunging and vortex flowpatterns are the typical flow regimes, which are mainly affected by the tangential intake design and flood discharge. However, thehydraulic flow transition between vortex and plunging flow patterns has received little attention, which may affect the dropshaftoperation during extreme

Counter-rotating axial-flow compressor (CRAC) is a promising technology to increase the thrust-to-weight ratio of aero-engines. Self-recirculating casing treatment (SRCT) is selected to explore its stability enhancement capacity in the CRAC. In the present work, an effective SRCT is designed by the design of experiment method, and the stability improvement potential of the SRCT and its mechanism of

To reduce the crosswind effect on high-speed trains, in this paper, by using the Improved Delayed Detached Eddy Simulation (IDDES) method and the SST k−ω turbulence model, a novel blowing measure is studied and compared by considering different positions of blowing slots on the train surface. The concerned blowing positions on the train surface include the top position (Top); windward side (WWS): the

Purpose This paper aims to focus on the cavitating flow around the Clark-Y hydrofoil when the dissolved air is taken into account as the third phase. As the RNG k-epsilon model yields poor prediction due to overestimation of viscosity, the modification approaches including density corrected method, filter-based model and filter-based density correction model are used, and the turbulence model is modified