2023 February - 45 articles
The dynamics of coalescence of small Lennard–Jones droplets as a function of droplet size and temperature is explored with molecular simulations. Droplet sizes vary from several hundred to several thousand molecules, and three different tempera...
The reduction in energy consumption and the increasingly demanding emissions regulations have become strategic challenges for every industrial sector. In this context, the glass industry would be one of the most affected sectors due to its high energ...
Internal waves are responsible for many important processes in the ocean environment (ocean ventilation, energy transfer from large-scale processes to turbulence, etc.). Our goal is to draw attention to the relatively little studied effect of interna...
Chromate and dichromate solutions used for the activation and passivation of cadmium and zinc galvanic coatings of metal products are widely used due to their ability to form corrosion-protective films. Therefore, in this article, we examined the kin...
The quest for the physical mechanisms underlying turbulent high-speed jet flows is underpinned by the extraction of spatio-temporal coherent structures from their flow fields. Experimental measurements to enable data decomposition need to comprise ti...
We propose a simple two-step approximation for the radial distribution function of a one-component two-dimensional Yukawa fluid. This approximation is specified by the key parameters of the system: coupling parameter and screening parameter. On the b...
Purpose: The analysis of pathological human left ventricular hemodynamics using high-resolved image-based blood flow simulations shows a major potential for examining mitral valve insufficiency (MI) under exercise conditions. Since capturing and simu...
Nowadays, wind energy is one of the most cost-effective and environmentally friendly energies in high demand due to shortages in fossil fuels and the necessity to reduce global carbon footprint. One of the main goals of wind turbine development is to...
The microstructure and suspended particle behavior should be considered when studying the flow properties exhibited by particle suspension. In addition, particle migration, also known as Segré–Silberberg effects, alters the microstructur...
Liquefied natural gas (LNG) is one of the most promising fuels for energy supply because it has a favorable combination of environmental and economic properties in connection with new trends aimed at the development of ecological and sustainable cons...
This paper presents an unsteady coupled heat transfer model in mine air and surrounding rock mass in the presence of distributed heat sources. The case of distributed heat sources is typical when analyzing the temperature distribution in mine excavat...
Low-fidelity methods such as the Blade Element Momentum Theory frequently provide rotor aerodynamic performances. However, these methods must be coupled to databases or correlations to compute heat transfer. The literature lacks correlations to compu...
The numerical solution of hyperbolic conservation laws requires algorithms with upwind characteristics. Conventional methods such as the numerical difference method can realize this characteristic by constructing special distributions of nodes. Howev...
Due to current EU regulations, constant-speed testing on test tracks is used for aerodynamic certification of heavy-duty vehicles (HDV). However, the aerodynamic development of HDVs is performed using wind tunnels and computational fluid dynamics (CF...
With regard to drying fresh grain prior to storage, the drying tower with a downward moving bed with hot air is often used, which always has high energy consumption during operation. To optimize the operation, according to the actual operating parame...
This paper deals with the design of an experimental circular channel model specially adapted for particle image velocimetry (PIV) measurements of airflow. The goal is to find a simple, fast, and functional approach for creating experimental models. T...
The integration of intermittent renewable energy resources to the grid system requires that hydro turbines regularly operate at part-load conditions. Reliable operation of hydro turbines at these conditions is typically limited by the formation of a...
In this study, divided into two parts, the effect on a two-dimensional backward-facing step flow (BFSF) of a cylinder placed downstream of the step was numerically investigated. While in Part 1, the numerical simulations carried out without the cylin...
The aerodynamic drag reduction of road vehicles is of continuing interest. The drag arising from the rear surfaces is usually the dominant component, but this can be alleviated by the tapering of the rear body. The effects on the aerodynamic characte...
This contribution aims at emphasizing the importance of ideal reactors in the field of environmental engineering and in the education of the corresponding engineers. The exposition presents the mass flow governing equations of the ideal reactors (bat...
In this paper, a new rheological model for the flow of phosphate-water suspensions is proposed. The model’s ability to replicate the rheological characteristics of phosphate-water suspensions under different shear rate conditions is evaluated u...
The problem of non-unique solutions at fictitious frequencies that can appear in the boundary element method for external acoustic phenomena described by the Helmholtz equation is studied. We propose a method to fully desingularise in an analytical w...
The backward-facing step flow (BFSF) is a classical problem in fluid mechanics, hydraulic engineering, and environmental hydraulics. The nature of this flow, consisting of separation and reattachment, makes it a problem worthy of investigation. In th...
The present work analyzes the thermal instability of mixed convection in a horizontal porous channel that is saturated by a shear-thinning fluid following Ellis’ rheology. The fluid layer is heated from below by a constant heat flux and cooled...
This paper is devoted to numerical modeling of a supersonic flow around a blunt body by a viscous gas with an admixture of relatively large high-inertia particles that, after reflection from the surface, may go beyond the shock layer and change the f...
For weakly nonlinear waves in one space dimension, the nonlinear Schrödinger Equation is widely accepted as a canonical model for the evolution of wave groups described by modulation instability and its soliton and breather solutions. When there...
Cloud formation is based on the fundamental principle of atmospheric convection, which involves the vertical transport of heat and moisture into an unstable environment. Convective transfer of moisture and heat in the form of turbulent fluxes over th...
(1) Background: Many studies suggest that migratory bird groups fly in a V-formation to improve their aerodynamic efficiency, the goal being to reduce their energy expenditure to fly longer distances. To further validate this hypothesis, we numerical...
The paper is devoted to an experimental study of the fluid motion excited by a light spherical body floating along the axis of a rotating vertical cylinder. The experiments are performed with fast rotation. The high-speed video recording examines the...
Bulk viscosity and acoustic wave propagation in polyatomic gases and their mixtures are studied in the frame of one-temperature and multi-temperature continuum models developed using the generalized Chapman–Enskog method. Governing equations an...
This article presents the results of a study on the dynamics of a volume of magnetic fluid levitating in a uniform magnetic field of an electromagnet experiencing an oscillatory shift. Samples with different physical parameters were considered, and t...
Machine learning-based modeling of physical systems has attracted significant interest in recent years. Based solely on the underlying physical equations and initial and boundary conditions, these new approaches allow to approximate, for example, the...
The article presents the results of processing non-emergency pressure measurements that are transmitted via the SCADA hardware and software system to the control center of the main gas pipeline. SCADA is widely used for real-time control of the modes...
Digital photography of cavitation in narrow gap flows, e.g., lubrication films in journal bearings or squeeze film dampers, demands a high time-resolution and a solution to approaching the particular spatial restrictions. Typically, the lubrication f...
Physics-informed neural networks (PINN) can be used to predict flow fields with a minimum of simulated or measured training data. As most technical flows are turbulent, PINNs based on the Reynolds-averaged Navier–Stokes (RANS) equations incorpo...
The formation of droplets in microchannels (droplet microfluidics) has a large number of applications, such as in micro-dosing and gas meters. This paper considers the dynamics of direct and inverse emulsions based on water, polydimethylsiloxane, and...
Scour is one of the main causes of hydraulic structural failures. The present experimental study examines the use of riprap, submerged vanes, and a combination of these for scour reduction around vertical walls and spill-through abutments under clear...
A parametric study of a ground-to-air heat exchanger (GAHE) using numerical models based on computational fluid dynamics with the finite volume method to evaluate the thermal potential of GAHE is presented. After the validation of the numerical code...
In the framework of innovative aerodynamics, active airfoils can be developed and exploited based on the integration of shape memory metal alloys (SMAs), allowing for surface adaptation, i.e., shape changes in response to operative thermal inputs, de...
Experimental studies have revealed that the introduction of a small amount (0.5% by volume) of permanent and chemically inert gas bubbles leads to the intensification of droplets disintegration in a liquid–liquid system (emulsification) in a pu...
This work explored the adsorption of Malachite Green (MG) dye by Acorn Pericarp (AP) in the context of biomass valorization. The Acorn Pericarp was analyzed by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction. The adsorption capac...
Investigations of fluid instability and density-driven convection in soils and rocks are motivated by both natural phenomena giving rise to ecological problems, and human activities. Knowledge about the admixture transportation by underground fluid f...
The displacement of a shear-thinning fluid by a denser and less viscous Newtonian fluid in a vertical duct is investigated using experiments and numerical simulations. We study how shear-thinning and increased viscosity contrast between the fluids af...
We investigate the solutions of a generalized diffusion-like equation by considering a spatial and time fractional derivative and the presence of non-local terms, which can be related to reaction or adsorption–desorption processes. We use the G...
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