Search results for "Fluid Flow"
showing 10 items of 405 documents
Thermoconvective instabilities in an inclined porous channel heated from below
2011
Abstract The thermoconvective instability in an inclined rectangular channel filled with a fluid saturated porous medium and heated from below with a uniform flux is investigated. A stationary parallel buoyant flow with a linear temperature change in the transverse direction is considered. The linear stability to transverse and longitudinal roll disturbances of this basic state is examined. The thermoconvective instability onset of transverse rolls occurs when the Darcy–Rayleigh number exceeds a critical value, that increases with the inclination angle. The critical Darcy–Rayleigh number is discontinuous at the inclination angle 23.4749° above the horizontal. It is shown that, when the incl…
Recent advances in the preparation of zeolites for the selective catalytic reduction of NOx in diesel engines
2019
Metal-exchanged zeolites with small pore sizes have attracted much attention in recent years due to their application in the selective catalytic reduction (SCR) of NOx in diesel engines. Typically, copper-chabazite (e.g. Cu-SSZ-13) has been gradually used as an SCR catalyst in heavy-duty diesel vehicles over the last decade due to its relatively excellent catalytic performance and stability. However, most SSZ-13 zeolites are still prepared via the traditional hydrothermal process in the presence of organic templates, requiring consecutive solid separation and thermal treatment steps to achieve the final zeolite products. In recent years, several strategies for the environmentally friendly p…
Investigation of Flow and Heat Transfer in Corrugated-Undulated Plate Heat Exchangers
2000
An experimental and numerical investigation of heat transfer and fluid flow was conducted for corrugated-undulated plate heat exchanger configurations under transitional and weakly turbulent conditions. For a given geometry of the corrugated plates the geometrical characteristics of the undulated plates, the angle formed by the latter with the main flow direction, and the Reynolds number were made to vary. Distributions of the local heat transfer coefficient were obtained by using liquid-crystal thermography, and surface-averaged values were computed; friction coefficients were measured by wall pressure tappings. Overall heat transfer and pressure drop correlations were derived. Three-dimen…
A mathematical simulation of high temperature induction heating of electroconductive solids
2007
The mathematical model of non-stationary coupled electromagnetic and thermal processes in polarizable and magnetizable axisymmetric electroconductive solids subjected to electromagnetic field generated by external currents is proposed. The processes parameters are connected through heat sources and temperature dependence of material characteristics. The problem is solved by finite element method. The process of induction heating of a finite steel cylinder is considered.
Solid inclusions in an electromagnetically induced recirculated turbulent flow: Simulation and experiment
2014
Abstract The paper presents the numerical and the experimental investigation of the particle-laden recirculated turbulent flow of liquid metal that is driven by electromagnetic force. Such flow is typical for induction metallurgical furnaces. The paper describes the behaviour of solid spherical particles that are mixed in the flow from a top surface of a melt and covers 3 stages of an admixing process as well as deposition of inclusions on the wall of a vessel. Experimental investigation of particles concentration at the quasi-stationary stage is fulfilled on the basis of a novel idea: ferromagnetic particles are proposed as a physical model of non-conductive inclusions in liquid metal at t…
Microwave heating of water in a rectangular waveguide: Validating EOF-Library against COMSOL multiphysics and existing numerical studies
2019
The purpose of this work is two-fold: first, we successfully validate our open-source tool EOF-Library, which efficiently couples Elmer FEM and OpenFOAM, against COMSOL Multiphysics, a commercial simulation package; second, we inform about significant discrepancies between our results and the experimental and simulation data found in a series of research papers. We reproduce the previously published numerical simulations wherein microwaves are supplied to a water domain through a rectangular waveguide, inducing convective flow. This is a conjugate problem with weakly coupled electromagnetics, heat transfer and fluid dynamics. It involves effects such as permittivity dependence on temperatur…
In-Gel Assay to Evaluate Antioxidant Enzyme Response to Silver Nitrate and Silver Nanoparticles in Marine Bivalve Tissues
2022
Silver is back in vogue today as this metal is used in the form of nanomaterials in numerous commercial products. We have developed in-gel electrophoretic techniques to measure the activity of the antioxidant enzymes catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPX), and used the same techniques in combination with HSP70 Western blot analysis to evaluate the effects of nanomolar amounts of silver nitrate and 5 nm alkane-coated silver nanoparticles in tissues of the marine bivalve Mytilus galloprovincialis (Lam.) exposed for 28 days in mesocosms. Our results showed a negligible effect for nanosilver exposure and dose-dependent effects for the nitrate form.
MHD free convection in a liquid-metal filled cubic enclosure. I. Differential heating
2002
An MAS-based subjective model for indoor adaptive thermal comfort
2015
The achievement of high level personalized sets of comfort parameters is contemplated within the more general context of the so-called smart buildings, where people, by means of the new communication technologies, become active actors to the process of the singling out and control of the best indoor conditions. This Dynamic Intelligence approach would usefully contribute to a better energy efficient and environmental friendly management of buildings. Multi-Agent schemes are suitable tools in this aim, since they are able to manage the user-building-plant system where the adaptivity of people to the indoor conditions is suitably achieved. In this paper a contribution to a development of the …
Nonlinear model based particle swarm optimization of PID shimmy damping control
2016
The present study aims to investigate the shimmy stability behavior of a single wheeled nose landing gear system. The system is supposed to be equipped with an electromechanical actuator capable to control the shimmy vibrations. A Proportional-Integrative-Derivative (PID) controller, tuned by using the Particle Swarm Optimization (PSO) procedure, is here proposed to actively damp the shimmy vibration. Time-history results for some test cases are reported and commented. Stochastic analysis is last presented to assess the robustness of the control system.