Modelling particulate flow during impregnation of dual-scale fabrics

Filtration of particles during impregnation of dual-scale fabrics is studied numerically for a number of configurations with a previously derived model. The initial position and size of the particles are varied. The main result is that structural composites can be tailor-made as to additional properties by such an approach.Godkänd; 2011; 20130418 (ysko

Permeability of clustered fibre networks : modelling of unit cell

The paper is focused on estimating the permeability of a clustered fiber network by variational methods. First, a laminar flow in ducts is considered by using polynomial trial functions. Then, a longitudinal flow through a square array is described by expanding the flow-rate field in trigonometric and Laurent series. Finally, a formal scheme for estimating the longitudinal permeability in a cluster with an irregular distribution of fibers is given. The irregular distribution is modeled by setting an individual effective radius for each fiber and then letting this fiber reach its minimum gravitational energy. The results obtained here form a basis for future predictions of the permeability of fibrous reinforcements.Validerad; 2003; Bibliografisk uppgift: MCM-2002 International Conference on Mechanics of Composite Materials, June 9-13, Riga (2002); 20070105 (ysko

Lattice-gas analysis of fluid front in non-crimp fabrics

The fluid flow front during impregnation of non-crimp fabrics is considered. Irregularities in fiber bundle architecture lead to generation of bubbles at the fluid front. The velocity of this interface is highly influenced by capillary forces mainly caused by the small fibers inside the bundles. In order to derive the shapes of the fluid front, a lattice-gas model has been applied. First, the macroscopic properties of the solved gas in the fluid are discussed. Next, the bubble inclusions are analyzed as to fluid-liquid interface position and concentrations of minor component in each phase. Finally, the flow in the interior of the fiber bundles is scrutinized, where the viscous stresses are considered, as well.Godkänd; 2008; Bibliografisk uppgift: CD-ROM; 20080828 (ysko

Endimensionell bäddmodell för simulering av torkning av järnmalmspellets

Järnmalmspellets är en högt förädlad produkt utvecklad av gruvindustrin för användning iexempelvis masugnar. För ett bandugnsverk sker pelletsprocessen huvudsakligen i fyra steg då en kontinuerlig bädd av pellets transporteras på rosterband genom torkzon, förvärmningzon,brännzon och kylzon. Genomströmmande luft används för att torka, sintra och kyla materialet ide olika zonerna. Då produktionen av järnmalmspellets är tids- och energikrävande finns deten naturlig drivkraft att förbättra processen så att produktionen kan optimeras medbibehållen produktkvalitet.För att i detalj studera torkzonen har en modell för konvektiv torkning av en enskildpellet tidigare tagits fram. Resultat från simuleringarna visar tydligt fyra torkningsfaser; i)förångning av vätska från pelletens yta, ii) förångning av vätska vid ytan samtidigt som vissinre förångning sker då ytan lokalt är torr, iii) torkning enbart på grund av inre förångningoch iv) kokning av vatten inuti pelleten [1]. Den framtagna torkningsmodellen har ävenapplicerats på en sfärisk geometri med syfte att undersöka hur fukthalten i inloppsluftenpåverkar torkningen [2]. Simuleringar visar att effekten av luftfuktighet främst uppkommeri början av den första torkningsfasen medan skillnaderna minskar i slutet av perioden då ettförlängt stadie av konstant torkhastighet fås vid höga luftfuktigheter.Ovanstående resultat visar att det är av stort intresse att även undersöka hur pellets i enpelletbädd påverkas av omgivande lufttemperatur och luftfuktighet. En endimensionellbäddmodell har därför utvecklats som ett komplement till enkulemodellen för attundersöka hur våttemperatur, pellettemperatur, torkhastighet etc. varierar som funktion avbäddhöjd i den första torkningsfasen. I modellen beräknas förångning från pelletsens ytamed motsvarande fukttransport genom den porösa bädden och det är därmed möjligt attutreda vilka områden i bädden som påverkas av eventuell återkondensation.Godkänd; 2011; 20111010 (ysko

INTERCOMPARAISON DE MODÈLES AUTONOMES ET DE MODÈLES EMBOÎTÉS À DEUX VOIES POUR LE SERVICE EN AVAL DU CMEMS

International audiencePrediction of hydrographic conditions e.g., sea level, temperature, salinity and currents in coastal-estuary continuum is the basis for climate change adaptation and mitigation and ecosystem-based management in coastal waters. In this study, we compare and develop two strategies: either use stand-alone Limfjord setup with boundary conditions from CMEMS or extend the CMEMS Baltic Monitoring Forecasting Centre (BAL-MFC) setup with a nested Limfjord domain. The resolution of Limfjord domain in about 185 m horizontal resolution. This domain is not covered by CMEMS, despite its importance for sea shipping, aquaculture and mussel fi sheries. The ocean model that is applied is the BAL-MFC HBM model (HIROMB-BOOS Model). The results show that both approaches are able to provide high quality sea level forecast for storm surge warning, temperature, salinity and currents with reasonably good quality for ecosystem-based management both for nested an stand-alone models. The models are able to handle the shallow thermoclines in summer as well as the strong tidal and wind driven transport through narrow straits in autumn and winter. Nested models usually have better performance and do not depend on possible change of CMEMS model that supplies boundary conditions. Nevertheless, stand-alone setup is attractive as it requires much less computational resources, can be tuned more effectively, less limits for increasing the resolution

Application of permeability network model to non-crimp fabrics

Godkänd; 2004; 20070913 (ysko

Flow-induced deformation of non-crimp fabrics during composites manufacturing

Flow induced alteration in permeability of deformable systems of fibres is studied. Low Reynolds number transversal flow through random arrays of aligned cylinders is considered by using a combined methodology of directly solving the twodimensional Navier-Stokes equations for the flow in the vicinity of a single fibre and minimisation of the dissipation rate in a system of fibres. The permeability of large random arrays increases always which is most apparent for compact systems with equal sized fibres. The permeability can also decrease but then for structured or small systems. The elastic deformations of fibre bundles are calculated basing microscopic fibre structure.Godkänd; 2009; 20091108 (stlu)</p

Derivation of dispersion coefficients in large random arrays of spheres and cylinders

Godkänd; 2012; 20121030 (andbra

Alteration of permeability caused by transversal flow-induced deformation of fibres during composites manufacturing

Godkänd; 2010; 20120920 (gunhel

Derivation of dispersion coefficients in large random arrays of spheres and cylinders

Godkänd; 2012; 20121030 (andbra