Numerical study of VIV over a flexible riser

This study is based on the simulation of the fluid-structure interaction on risers. We aim to quantify the structural response of these long flexible pipes, used for the extraction of offshore petroleum when they are subjected to marine currents. Toe occurring phenomenon is known as VIV (Vortex induced VIbration). These problems are a relevant challenge for several offshore companies, which are associated with K-Epsilon in a Citeph project. Toe project's goal is to use the FSI simulation tool developed by K-Epsilon and initially used for the simulation offlexible membranes such as sails, to model these VIV phenomena. Toe problem of VIV in the case of a riser is a strongly coupled problem, meaning that the added mass is not negligible compared to the mass of the structure. This can be challenging for most fluid-structure interaction software. A strongly coupled algorithm is presented [6]. First, numerical results of fluid around cylinders are presented and compared to experimental results ([l], [10]) with several turbulence models, and time step sizes. Toen, Chaplin's benchmark is presented with experimental / numerical comparison [3]

Influence of a thermal treatment on the functionality of hen's egg yolk in mayonnaise

The viscosity and emulsifying properties of egg yolk submitted to a heat treatment at 68 °C for up to 11 min were investigated in a standard mayonnaise recipe. Heating of the egg yolk prior to emulsification was found to lead to a reduction of the average oil droplet size in mayonnaise of up to 40% compared to non-heated egg yolk. This led to an increased viscosity and greater pseudoplasticity of the mayonnaise prepared with heated egg yolk. In order to investigate the effect of egg yolk heating on the rheological properties of the mayonnaise independently from the oil droplet size, emulsions having various median oil droplet diameters were prepared with non-heated and heated egg yolk. This work shows that heating of egg yolk prior to emulsification significantly impacts the rheological properties of mayonnaise when the median oil droplet diameter exceeds 5 lm. The presence of thermally unfolded and interacting proteins in the aqueous lamella of continuous phase surrounding each oil droplet of the mayonnaise may explain the impact of heating on the rheological properties of the product. The increased thixotropy observed in mayonnaise prepared with heated egg yolk may reflect the formation of a network of oil droplets connected by weak bonds formed between proteins adsorbed at the interface and within the continuous phase. c 2005 Elsevier Ltd. All rights reserved

Numerical and experimental analysis of unsteady separated flow behind an oscillating car model

International audienc

Experimental and numerical study of unsteady wakes behind an oscillating car model

International audienc

Experimental and numerical of the wake of a simplified car model in incidence

International audienc

A comparison between full RANSE and coupled RANSE-BEM approaches in ship propulsion performance prediction

International audienc

Investigation of water depth and basin wall effects on KVLCC2 in manoeuvring motion using viscous-flow calculations

National audienceThe objective of the NATO AVT-161 workinggroup is to assess the capability of computational tools toaid in the design of air, land and sea vehicles. For seavehicles, a study has been initiated to validate tools that canbe used to simulate the manoeuvrability or seakeepingcharacteristics of ships. This article is part of the workconcentrating on manoeuvring in shallow water. Asbenchmark case for the work, the KVLCC2 tanker fromMOERI was selected. At INSEAN, captive PMMmanoeuvring tests were conducted with a scale model ofthe vessel for various water depths. Several partners in theAVT group have conducted RANS calculations for aselected set of manoeuvring conditions and water depthsfor the bare hull. Each partner was asked to use their best practice and own tools to prepare the computations and runtheir flow codes. Specific instructions on the post-processingwere given such that the results could be comparedeasily. The present article discusses these results. Detaileddescriptions of the approach, assumptions, and verificationand validation studies are given. Comparisons are madebetween the computational results and with the experiments.Furthermore, flow features are discussed

The influence of distributed chemical reaction groups in a multiphase coffee bean roasting model

The coffee industry relies on fundamental research to improve the techniques and processes related to its products. While recent theoretical and modelling work has focused on the heat and mass transfer processes within roasting coffee beans, modelling and analysis of chemical reactions in the context of multiphase models of roasting beans has not been well-studied. In this paper, we incorporate modified evaporation rates and chemical reaction groups to improve existing mathematical models of roasting coffee beans. We model the phase change from liquid to vapour water within the bean during roasting using first-order Arrhenius-like global reactions, and for other components of the bean, we consider a threecomponent solid phase model which includes sucrose, reducing sugars, and other organic compounds, which allows for porosity of the solid matrix to vary during the roasting process. We non-dimensionalise and then solve the multiphase model numerically, comparing the simulations with data we have collected through full bean and chopped bean experiments. We demonstrate that numerical solutions of the enhanced multiphase model with global water reactions and three-component solid phase reactions agree with experimental data for the average moisture content in whole beans and small chunks of bean, but that the data allows for a range to possible parameter values. We discuss other experimental data that might be collected to more firmly determine the parameters and hence the behaviour more generally. The indeterminacy of the parameters ensures that the additional effects included in the model will enable better understanding the coffee bean roasting process