Laboratory investigation of tomography-controlled continuous steel casting

More than 96% of steel in the world is produced via the method of continuous casting. The flow condition in the mould, where the initial solidification occurs, has a significant impact on the quality of steel products. It is important to have timely, and perhaps automated, control of the flow during casting. This work presents a new concept of using contactless inductive flow tomography (CIFT) as a sensor for a novel controller, which alters the strength of an electromagnetic brake (EMBr) of ruler type based on the reconstructed flow structure in the mould. The method was developed for the small-scale Liquid Metal Model for Continuous Casting (mini-LIMMCAST) facility available at the Helmholtz-Zentrum Dresden-Rossendorf. As an example of an undesired flow condition, clogging of the submerged entry nozzle (SEN) was modelled by partly closing one of the side ports of the SEN; in combination with an active EMBr, the jet penetrates deeper into the mould than when the EMBr is switched off. Corresponding flow patterns are detected by extracting the impingement position of the jets at the narrow faces of the mould from the CIFT reconstruction. The controller is designed to detect to undesired flow condition and switch off the EMBr. The temporal resolution of CIFT is 0.5 s

The effect of using a high-albedo material on the Universal Temperature Climate Index within a street canyon

Abstract This study investigates the effect of different high-albedo adaptation strategies on air temperature, mean radiant temperature and the Universal Temperature Climate Index (UTCI) for a single idealized 2D street canyon. A simulation model has been used that computes these variables at 1 meter spatial resolution. Using high-albedo materials for all canyon surfaces decreases air temperature but increases mean radiant temperature, thereby increasing the UTCI. Differences in mean radiant temperature are much larger compared to differences in air temperature inside a single street canyon, and therefore have a larger impact on the UTCI. The impact of albedo-differences on the UTCI are relatively small compared to the large impact of shading. The best strategy for the outdoor environment with building height to width ratio H/W=0.5 was found to be a uniform albedo of 0.2. For H/W=1.0, an * Corresponding author Email address: [email protected] (P.J.C. Schrijvers) Preprint submitted to Building and Environment October 27, 2014 albedo gradient from a high albedo at the bottom part and a low albedo at the top of the vertical walls showed the lowest UTCI. Air temperature increases slightly compared to a uniform albedo, but a large decrease in mean radiant temperature and the UTCI was found. Although using high-albedo material can mitigate the atmospheric urban heat island effect, it is very likely to increase pedestrian heat stress, which might not be the desired result

Computational Simulations of Magnetic Particle Capture in Arterial Flows

The aim of Magnetic Drug Targeting (MDT) is to concentrate drugs, attached to magnetic particles, in a specific part of the human body by applying a magnetic field. Computational simulations are performed of blood flow and magnetic particle motion in a left coronary artery and a carotid artery, using the properties of presently available magnetic carriers and strong superconducting magnets (up to B ≈ 2 T). For simple tube geometries it is deduced theoretically that the particle capture efficiency scales as \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\eta \sim \sqrt{{Mn}_{\rm p}}$$\end{document}, with Mnp the characteristic ratio of the particle magnetization force and the drag force. This relation is found to hold quite well for the carotid artery. For the coronary artery, the presence of side branches and domain curvature causes deviations from this scaling rule, viz. η ∼ Mnpβ, with β > 1/2. The simulations demonstrate that approximately a quarter of the inserted 4 μm particles can be captured from the bloodstream of the left coronary artery, when the magnet is placed at a distance of 4.25 cm. When the same magnet is placed at a distance of 1 cm from a carotid artery, almost all of the inserted 4 μm particles are captured. The performed simulations, therefore, reveal significant potential for the application of MDT to the treatment of atherosclerosis

Energy spectra and turbulence generation in the wake of magnetic obstacles

Numerical simulations and analysis of flow and heat transfer of an electrically conducting fluid past magnetic obstacles are reported. We studied the channel flow configuration with electrically and thermally insulated horizontal walls containing a single or multiple (two or three) magnetic dipoles. Different values of the interactive parameter 0 ? N ? 50 and with a fixed value of Re = 103 are simulated. Detailed insights into energy spectra and turbulence generation in the wake of magnetic obstacles are provided. Although the temperature is a passive scalar, strong dissimilarities between mechanisms of production of the turbulent kinetic energy and temperature variance are observed. The long-term averaged second moments of velocity and temperature revealed the presence of anisotropic turbulence and countergradient diffusion of turbulent heat fluxes. It is concluded that configurations with multiple magnetic dipoles can be utilized in practical applications where the local generation of turbulence and intensification of mixing and heat transfer are required.ChemE/Chemical EngineeringApplied Science