Abstract

The work presented in this paper describes a novel multi-phase discharge and dispersion model capable of predicting the near-field fluid dynamics and phase-transition phenomena associated with accidental CO2 releases. Also presented in this paper are previously unpublished data describing the near-field structure of a number of largescale CO2 experimental releases, obtained through the EU-FP7 CO2PipeHaz (2009) project. The calculations employed an adaptive finite-volume grid algorithm to solve the Favre-averaged fluid-flow equations. This equation set was closed with the inclusion of both a two-equation k-e model and a second-moment Reynolds stress model to represent turbulent fluctuations. Results demonstrate the superior performance of the Reynolds stress transport model when compared to its compressibility-corrected counterpart. Document type: Part of book or chapter of book

Abstract

A research program was carried out at the University of Illinois in which develops a scientific approach to gas-liquid flows that explains their macroscopic behavior in terms of small scale interactions. For simplicity, fully-developed flows in horizontal and near-horizontal pipes. The difficulty in dealing with these flows is that the phases can assume a variety of configurations. The specific goal was to develop a scientific understanding of transitions from one flow regime to another and a quantitative understanding of how the phases distribute for a give regime. These basic understandings are used to predict macroscopic quantities of interest, such as frictional pressure drop, liquid hold-up, entrainment in annular flow and frequency of slugging in slug flows. A number of scientific issues are addressed. Examples are the rate of atomization of a liquid film, the rate of deposition of drops, the behavior of particles in a turbulent field, the generation and growth of interfacial waves. The use of drag-reducing polymers that change macroscopic behavior by changing small scale interactions was explored. Document type: Report

Abstract

This study presents the results from detailed experiments of the two-phase pressurized flow behavior during the rapid filling of a large-scale pipeline. The physical scale of this experiment is close to the practical situation in many industrial plants. Pressure transducers, water-level meters, thermometers, void fraction meters, and flow meters were used to measure the two-phase unsteady flow dynamics. The main focus is on the water–air interface evolution during filling and the overall behavior of the lengthening water column. It is observed that the leading liquid front does not entirely fill the pipe cross section; flow stratification and mixing occurs. Although flow regime transition is a rather complex phenomenon, certain features of the observed transition pattern are explained qualitatively and quantitatively. The water flow during the entire filling behaves as a rigid column as the open empty pipe in front of the water column provides sufficient room for the water column to occupy without invoking air compressibility effects. As a preliminary evaluation of how these large-scale experiments can feed into improving mathematical modeling of rapid pipe filling, a comparison with a typical one-dimensional rigid-column model is made. Keywords: Experimentation, Large-scale pipeline, Unsteady flow, Two-phase flow, Air–water interface, Flow-regime transition

Abstract

CityMobil was an integrated project in the Sixth Framework Program of the European Union. The objective of the project was to achieve more effective organization of urban transport for more rational use of motorized traffic with less congestion and pollution, safer driving, a higher quality of living, and enhanced integration with spatial development. This objective was reached by developing integrated traffic solutions: advanced concepts for innovative autonomous and automated road vehicles for passengers and goods embedded in an advanced spatial setting. The project was split into two parts: (a) research and development and (b) demonstration. The primary aim of the research and development part was to identify, address, and, where possible, eliminate barriers that still blocked the large-scale implementation of automated transport systems in urban traffic. The heart of the demonstration part consisted of three large-scale implementations of automated transport systems in urban areas and a number of smaller showcases and demonstrations. CityMobil was a 5-year project that started in May 2006 and ended in December 2011. The project results were presented at a final conference in Brussels, Belgium. This paper provides an update of a paper presented in 2009 and includes an overview of the final CityMobil results. The detailed results are available on the CityMobil website: www.citymobil-project.eu.

Abstract

There is a trend in Advanced Driver Assistance systems towards increased automation. Current systems and near-future systems will not yet be able to deal with all different situations that can be encountered and therefore need to share control of the vehicle with the driver. To safely and comfortably share control, a method for the transition of control (from manual to automated driving and vice versa) needs to be developed. This involves answering research questions like ‘how should the system take over’, ‘how can the driver take back control’, ‘can the driver be regarded as a backup if the system fails’, etc. This paper concentrates on finding different parameters and settings that may influence the transition of control for a ‘virtual tow bar’ system that is being developed at TNO . This serves as a first step to finding more general guidelines for transition of control and to develop necessary procedures, models and tools to evaluate these guidelines. Results of a first simulator experiment are presented and discussed.

Abstract

large number of pipelines in the petroleum industry simultaneously transport gas and liquid. Transient behaviour of multiphase flow is frequently encountered in these pipelines. A common example is severe slugging that can occur in multiphase flow systems where a pipeline segment with a downward or even horizontal inclination is followed by a riser segment with an upward inclination. Transient flow conditions associated with severe slugging are relatively slow. Therefore, a transient drift flux model consisting of one momentum balance equation might suffice to express the dynamics of severe slugging. We present a transient drift flux model to simulate severe slugging phenomenon in pipeline-riser systems. The present model contains recently published correlations by Shi et al. for the drift flux slip model which cover the complete range of flow conditions without introducing any discontinuities in the calculated flow parameters. Thus, the transient simulations are converging rapidly and efficiently without applying any form of smoothing. The present model is tested against experimental data for severe slugging showing a better performance than previously published models.

Abstract

Skin contraction during wound healing is mainly caused by fibroblasts (skin cells) and myofibroblasts (differentiated fibroblasts) that exert pulling forces on the surrounding extracellular matrix (ECM). Modelling is done in multiple scales: agent–based modelling on the microscale and continuum–based modelling on the macroscale. The momentum equilibrium equation is used to simulate this phenomenon in both models, with different expression of the cellular forces. In this manuscript, we managed to rigorously establish the link between the two modelling approaches for both closed–form solutions and finite–element approximations in one dimension.

Abstract

Biot's theory of coupled mechanical-transport behavior of porous materials is applied in the framework of discrete mesoscale modeling. The contribution presents asymptotic expansion homogenization of the discrete poromechanical model. The macroscale becomes homogeneous and continuous and contains all the coupling effects. In contrast, the microscale is discrete and completely decoupled, separate representative volume elements (RVEs) appear for mechanical and mass transport problems. Linear elastic material behavior is assumed, therefore response of the RVEs can be pre-computed in advance and used repetitively at integration points of the macroscopic model.