A model has been developed to predict the movement of oblate and prolate particles on amicro- and nano-scale in laminar channel flow, both for purposes of statistical aggregationand to study motion of single particles. For the purpose of this thesis the model has beenadapted to examine particle deposition patterns in the human lung and the filtration ofparticles during manufacturing of composites, but the possibilities of the model extendto all areas where the particle Stokes and Reynolds numbers are small.To examine the influence the breathing pattern has on the deposition of inhalednano- and micro-fibres deposition rates were compared at different injection points ofthe breathing cycle, where maximum deposition was found when the particles releasedat the beginning of the respiratory cycle while minimum deposition occurred when therelease came at peak inhalation. A comparison between a quasi-steady flow and a cyclicflow was done and it was found that a quasi-steady solution provides a reasonably goodapproximation if the velocity used is a mean of the velocity during the residence time ofthe simulations.A statistical study was done to compare the deposition rates of oblate and prolateparticles of different size and aspect ratio as they travel down narrowing bronchi in asteady, fully developed parabolic flow field. The model shows a clear correlation betweenincreased particle size and increased deposition, it also consistently yielded a higherdeposition rate for oblate particles compared to prolate particles with a similar geometricdiameter. A study of the motion and orientation of single oblate and prolate particleswith large aspect ratio and the same geometric diameter has also been done.In liquid moulding of fibre reinforced composites the resin can be enhanced by nanoandmicro-particles to give the final product additional properties. This is a processthat can be simulated by approximating the gap formed between the fibre bundles to achannel flow with a radially suctioning component caused by the capillary pressure in themicro channels in the bundles. First this flow field is described with a radial componentthat is constant over the length of the channel and compared with a flow purely drivenby an applied pressure gradient without radial forces. Particle size showed a small butstill noticeable influence, particularly for larger particles under the influence of gravity.The second flow field used is time dependent where the flow front in the bundlesand channel mimics that of previous observations. There is initially a period where theflow front in the channel is leading but the radial capillary fluid transport causes thisto retreat and be overtaken by the flow front in the bundles. Particles mixed in theresin will in general travel with a velocity greater than that of the fluid front until theradial velocity component at that point filters the particles by transporting them to thechannel wall. Particle geometry has a smaller impact on the deposition rates in compositemanufacturing than in inhalation since the effect of Brownian forces and gravity are muchsmaller, although there is still some discernible patterns such as a higher deposition ratefor spherical particles during the transport to the flow front.

A constantly increasing number of advanced driver assistance systems are implemented in cars.The driver is required to interpret the data reported by these systems while driving, and thereforeit is important to know how the information signals provided by such systems affect the driver.Driving relies to a large extent on vision, and most current advanced driver assistance systemsuse visual information, requiring visual attention from the driver. This conflicts with the drivingtask and leads to an increase in inattention and in cognitive and visual workload. Off-loadingvisually demanding tasks to other sensory modalities should be beneficial in terms of the driver’sability to divide attention resources. The aim of this thesis is to gain knowledge on how the driveris affected by information and interaction with driver assistance systems utilising 3D auditorydisplays. The goal is to provide knowledge of how to create robust interfaces that assist the driverwhile maintaining the necessary safety aspects while driving.The first paper investigated the importance of sound source placement within the car compartment.Since sound can be a very effective means of capturing attention, it could cause dangeroussituations if used in the wrong way. If sound is used to draw attention, one must be sure to notdraw the driver’s attention away from something more critical. The study showed that soundcan improve attention to the road when the sound source location is in front of the driver.Previous research has shown that a combination of sensory modalities increase the robustnessof perception. To avoid additional load on the visual modality, the second paper investigatedthe usefulness of vibrotactile information, in combination with auditory and/or visual signals.There was no significant increase in performance when adding vibration to a sound signal, butvibration and sound on their own led to similar performance. It can be argued, however, thatcombinations are still useful since they reduce the risk of an important signal being missed orneglected. In this investigation, all signals containing a visual component provided the fastestresponse time.The third paper investigated the usefulness of a 3D auditory display applied on a parking assistancesystem. A user study was conducted to evaluate drivers’ workload and performancewhen using different system implementations. It was found that a 3D auditory display was wellreceived as long as the sound only came from one direction at a time. Providing too much informationto the driver by using simultaneous sound sources at different locations was perceived asconfusing and annoying. In some cases, the effort required to perform a successful parking wassignificantly reduced when using a 3D auditory display system compared to a traditional parkingassistance system using only two sound sources. There were also indications that 3D soundcan reduce drivers’ mental workload and frustration with parking assistance systems.Placing sound sources in the car where they are most suitable can be difficult, especially if soundsources outside the car are required. The fourth paper investigated if it would be possible to use acrosstalk cancellation technique in combination with binaural recordings to reproduce 3D audiousing only two loudspeakers in the car compartment. It was found that when the loudspeakersare placed close to the ears of the driver, crosstalk cancellation can be effective inside the car compartment by avoiding strong reflections. Closely placed loudspeakers reduce filter creationcomplexity and improve sound quality.The fifth paper tackles the problems of within-the-head perception and front-back confusion,commonly found in binaural recordings and synthesis. It has been shown that reverberant binauralsounds are perceived more externalised than anechoic sounds, and tend to suffer less fromfront-back confusion. However, information sound signals should rarely be reverberant. Theidea was to create an image-source model with focus on early reflections and compare it withtraditional artificial head recordings. The image-source model performed better than the artificialhead recordings in terms of front-back confusion, and at the same time considerably limitedthe inherent room acoustics in the sound.In conclusion, meaningful and informative sound signals can raise driving performance if theyare placed in front of the driver. This encourages the driver to maintain focus on the road, byusing the attention capture capabilities of sound. A 3D auditory display can be beneficial forsystems such as parking assistance, since it helps lowering driver effort, mental workload andfrustration. Also, 3D auditory displays increase the drivers’ sense of safety and comfort, by augmentingthe drivers’ surrounding and thereby increasing their situational awareness. If a 3Dauditory display should be implemented in the car, a transaural system with crosstalk cancellationshowed promise for virtual sound source reproduction. However, binaural synthesis hasinherent problems that need to be addressed, specifically front-back confusion. It is hard to recommendusing crosstalk cancellation with binaural synthesis at the current state for locationcritical signals due to localisation confusion. However, using more than one modality for informationsignals makes the signals difficult to miss and could also help with the front-back confusionproblem, but further research is needed. If a transaural system with crosstalk cancellationis chosen as reproduction format, make sure to carefully select the loudspeaker placementsin order to avoid as many problems with filter generation as possible, since this will cause errorsin crosstalk suppression and affect the reproduction sound quality. Directive loudspeakersmounted in the neck rest, or ceiling, are good candidates for implementation.

Before presenting the Sheet Moulding Compound (SMC) process, which is the primarily focus of this work, a literature survey is carried out to deal with fibre reinforced polymer composites in general. Then the first part of this work is presented and is primarily focused on experimental visualisation of the flow during mould closure of SMC. Circular plates are manufactured with industry scale equipment at close to production conditions. Special attention is given to the advancing flow front, for which the full complexity is captured by means of continuous high resolution close-up monitoring. From the experimental visualisation of the flow front, three phases are defined, namely squish, flow, and boiling. During the initial phase, squish, outer layers do not remain outer layers, the actual flow is very complex and air is likely to be entrapped. The governing process parameters during this phase are mould temperature, mould closing speed and amount of preheating in the mould. During the second phase, flow, the flow is stable and seemingly viscous. During the last phase, boiling, bubbles are observed in the low pressure region at the flow front, favouring the void content both internally and on the surface. Based on a chemical analysis including mass spectrometry and thermogravimetry, the gas is probably styrene. In the second part it is investigated if an inverse modelling approach by proportional regularisation can be applied to mimic the pressure distribution during compression moulding of SMC. The process is simulated with Computational Fluid Dynamics and the mastered parameter, the viscosity of the SMC, is allowed to vary as a function of time. A grid refinement study of two ways to model the process and for three fictitious pressure scenarios yields that the suggested approach work very well and that the numerical errors can be minimised as desired. Finally a validation process is carried out showing that to get quantitative agreements of the whole pressure field more advanced viscosity models must be used. In order to verify the inverse modelling system have to important errors are studied. Firstly the error between calculated and experimental pressure, secondly the discretisation error due to solving the problem for many small volumes. Both have to be minimized and the later is studied with Richardson's extrapolation. The conclusions are that the initial guess is very important for predictions in the beginning of the simulation. / Godkänd; 2005; 20070108 (haneit)

Hydropower is one of the main sources for Sweden’s energy, which is clean and renewable. It is a clean energy source because no fuels are burned which does not pollute the air and it is a renewable energy source as it only uses natural water cycle for generating energy. However, hydropower has some consequences in nature, such as creating dams in rivers and changing water flow directions, which lead to some problems for migrating fishes. These fish migration problems are mostly studied from a biological point of view but more detailed studies are required from a fundamental fluid mechanics point of view. Fish migrates when ecological imbalance is created and one of the reasons for this imbalance is having dams for hydropower. Some dams have fishways or fish ladders to allow fish to migrate past the dam and during swimming or passing this fishway or fish ladder, fish has to tackle some sort of flow obstructions like, turbine intakes, stones and concrete structures etc. Fluid flow characteristics in fish ladders or fishways during fish migration is crucial for designing effective fishways to migrate fishes effectively. Flow characteristic measurements can provide quantitative information of the velocity distribution in fish ladders, which has strong correlation with the attraction of of fish. Recent research suggests that turbulence also has a large effect on fish migration. This is why obtaining flow information from well-defined turbulent flows, such as flow past cylindrical objects is the prime aim of these measurements. Particle Image Velocimetry (PIV) and Laser Doppler Velocimetry (LDV) have become the most popular and promising techniques for these types of non-contact measurements. PIV techniques are used to visualize and measure the flow characteristic in a selected area while LDV techniques are suited for point-based measurement. The works included in this thesis are reviewing PIV techniques previously used in fish movement related studies, LDV measurements both at upstream (bow wake) and downstream wake of cylindrical obstructions and finally Computational Fluid Dynamics (CFD) for validation of experimental measurements. The results find relatively acceptable agreement between CFD and experiments with some disparities.

Computational Fluid Dynamics (CFD) approaches have been developed to studypollution reduction in the manufacturing phase and heat transfer in the packed beds of iron ore pellets. CFD is a versatile tool that can be applied to study numerous problems in fluid mechanics. In the present thesis it is used, verified and validated to reveal the fluid mechanics of a couple of processes taking place during the drying and sintering of iron ore pellets. This is interesting in itself and can facilitate the optimization of the production as to product quality of the pellets, reduced energy consumption and reduction of emissions such as NOx and CO2. The practical aim with the pollution reduction research project is to numerically study the use of Selective Non-Catalytic Reduction (SNCR) technologies in gratekiln pelletizing plants for NOx reduction which had, to the best knowledge of the author, never been used in this context before despite that it is commonly used in cement and waste incineration plants. The investigation is done in several stages: 1)Reveal if it is possible to use the technique with the two most commonly reagents, ammonia and urea. 2) Derive a chemistry model for cyanuric acid (CA) so that this reagent also can be scrutinized. 3) Compare the reagents urea and CA in the gratekiln pelletizing process.A CFD model was developed and numerical simulations were carried out solving the flow field. A model for spray injection into the grate was then included in the model enabling a study of the overall mixing between the injected reagent droplets and the NOx polluted air. The results show that the SNCR technique with urea and CA may reduce the amount of NOx in the grate-kiln process under certain conditions while ammonia fails under the conditions investigated. The work also lays grounds for continued development of the proposed chemistry model by the adding of reactions to the RAPRENOx-process for CA as reagent, facilitating an extension to ammonia and urea as reagents.The grate-kiln plant consists of a grate, a rotating kiln and an annular cooler. The pellets are loaded onto the grate to shape a bed with a mean height of about 0.2 m. The pellets in LKABs processes consist mainly of magnetite and different additives chosen to fit the demand from the customer. Throughout the grate a temperature gradient is formed in the bed. This gradient should be as even as possible throughout the grate to ensure an even quality of the pellets. Method to study this numerically is the second main task in this thesis. The aim is to find out how temperature distributions in the bed can be modeled and adjusted. Of special interest is how the incoming process gas, leakage, and the detailed composition of the pellet bed influence the heat transfer through the bed. To achieve the goals and create a trustful model for the heat transfer through the packed bed the model must be build up in steps. Heat transfer to a bed of iron ore pellets is therefore examined numerically on several scales and with three methods: a one-dimensional continuous model, a discrete three-dimensional model and traditional computational fluid dynamics.In a first study the convective heat transport in a relatively thin porous layer ofmonosized particles is set-up and computed with the one-dimensional continuous model and the discrete three-dimensional model. The size of the particles is only one order of magnitude smaller than the thickness of the layer. For the three-dimensional model the methodology applied is Voronoi discretization with minimization of dissipation rate of energy. The discrete model captures local effects, including low heat transfer in sections with low speed of the penetrating fluid and large velocity and temperature variations in a cross section of the bed. The discrete and continuousmodel compares well for low velocities for the studied uniform boundary conditions. When increasing the speed or for a thin porous layer however, the continuous model diverge from the discrete approach if a constant dispersion is used in the continuous approach. The influence is larger from an increase in pellet diameter to bed height ratio than from increased velocity. In a second study the discrete model is compared to simulations performed with CFD. If local values are of importance the discrete model should always be used but if mean predictions are sufficient the CFD model isan attractive alternative that is easy to couple to the physics up- and downstream the packed bed. The good agreement between the discrete and continuous model furthermore indicates that the discrete model may be used also for non-Stokian flow in the transitional region between laminar and turbulent flow, as turbulent effects show little influence of the overall heat transfer rates in the continuous model. / Godkänd; 2015; 20150407 (burper); Nedanstående person kommer att disputera för avläggande av teknologie doktorsexamen. Namn: Per E.C. Burström Ämne: Strömningslära/Fluid Mechanics Avhandling: Computational Fluid Dynamics of Processes in Iron Ore Grate-Kiln Plants Opponent: Professor Xue-Song Bai, Avd för strömningsteknik, Institutionen för energivetenskaper, Lunds tekniska högskola, Lund Ordförande: Professor Staffan Lundström, Avd för strömningslära och experimentell mekanik, Institutionen för teknikvetenskap och matematik, Luleå tekniska universitet Tid: Torsdag 4 juni kl 13.00 Plats: E231, Luleå tekniska universitet

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Product sound design has received much attention in recent years. This has created a need to develop and validate tools for developing product sound specifications. Elicitation of verbal attributes, identification of salient perceptual dimensions, modelling of perceptual dimensions as functions of psychoacoustic metrics and reliable auralisations are tools described in this thesis. Psychoacoustic metrics like loudness, sharpness and roughness, and combinations of such metrics into more sophisticated models like annoyance, pleasantness and powerfulness are commonly used for analysis and prediction of product sound quality. However, problems arise when sounds from several sources are analysed. The reason for this complication is assumed to be the human ability to separate sounds from different sources and consciously or unconsciously focus on some of them. The objective of this thesis was to develop and validate methods for product sound design applicable for sounds composed of several sources. The thesis is based on five papers. First, two case studies where psychoacoustic models were used to specify sound quality of saxophones and power windows in motor cars. Similar procedures were applied in these two studies which consisted of elicitation of verbal attributes, identification of most salient perceptual dimensions and modelling of perceptual dimensions as functions of psychoacoustic metrics. In the saxophone experiment, psychoacoustic models for prediction of prominent perceptual qualities were developed and validated. The power window experiment showed that subjects may judge only parts of the sound. Power window sound consists of the motor sound and the scratching of a window sliding over the seal. The motor sound was filtered out and models developed using motor sound alone showed good agreement with listening tests. This demonstrated the human ability to separate sound from different sources and pointed out the importance of handling auditory stream segregation in the product sound design process. In Paper III sound sketches (simple auralisations) was evaluated as a way to assess sounds composed of several sources. Auralisation allows control of the contributions of different sources to a sound at the listening position. This way, psychoacoustic analysis and listening tests may be carried out on the contributions from sources separately and as an ensemble. Sound sketches may also serve to specify a target sound for a product. In Papers IV and V, the precision of auralisations related to intended use was investigated. Auralisations were made by filtering engine sounds through binaural transfer functions from source locations to the listening position in a truck cabin. In Paper IV simplifications of auralisations of one source were compared to artificial head recordings. For idling sounds auralisations through binaural transfer functions with a resolution of 4 Hz or better, or smoothed with maximum 1/96 octave moving average filters were found to preserve perceived similarity to artificial head recordings. In Paper V the effect of simplifications of transfer functions on preference ratings of auralisations was examined. This is of interest in applications where audible differences may be acceptable as long as preference ratings are unaltered, e.g. when auralisations are used as rough sound sketches. At 500 rpm idle speed, a resolution of 32 Hz or better, or smoothing with maximum 1/24 octave moving average filters showed no significant alteration of subject preference ratings. These figures may serve as guide for required accuracy in auralisations used for evaluation of idling sounds in truck cabins. To conclude, psychoacoustic analysis of total sound may be used for prediction of perceived sound quality as long as the sound is generated by one source. When several sources generate sound, auditory stream segregation effects in combination with cognitive effects may deteriorate the results. Auralisation is a useful tool in such cases, since it makes it possible to analyse the effects of contributions from each source. It can also be used for making sound sketches which can serve as support in the design process. / Godkänd; 2008; 20080925 (ysko)

This thesis contains an analysis of fluid flow and heat transfer problems in the resin transfer moulding (RTM) process for manufacturing of polymer based fibre composites and it consists of five separate papers. The permeability of unidirectional fabrics, that are often used in advanced composites, is considered in Paper A and a theory for the permeability dependence on the micro geometry is developed. The theory is based on lubrication theory for narrow gaps which is motivated by the fact that most of the flow resistance comes from a small region where the fibres are closest to each other. Despite this limitation the results agree excellently with numerical results. 'Me best performance of the theory is expected at high fibre volume fractions (Vf) but the dependence on Vf is surprisingly good even at as low values as 0.3. Although the theory is formulated for an idealised geometry it can be used to predict the variation of the anisotropic permeability tensor with fibre volume fraction in real fabrics after fitting of three model parameters. Paper B is a study of the influence from different process parameters on the void content in the laminate. The void content is shown to be reduced strongly by an applied vacuum during mould filling. The main mechanism for void formation appears to be mechanical entrapment at the flow front. The voids are convected by the flow so that their concentration is highest close to the flow front. Microscopy investigation of the bubbles show that they are of two basic types, large spherical bubbles in the interstices between fibre bundles and smaller cylindrical bubbles inside the fibre bundles. The positive influence of vacuum compared to no vacuum can be explained as a combined effect of an increased mobility due to larger volume changes during mould filling and compression by the increased pressure during cure. In Paper C a comparison is made between the mould filling times for different injection strategies. The possible alternatives for a normal laminate are point injection, edge injection and peripheral injection. Theoretical results are derived that can be used to estimate the mould filling time with the different alternatives. In addition, fundamental theoretical results are derived from the governing equations showing the scaling of the mould filling time with the process parameters. This analysis also shows that the flow front motion during mould filling is only a function of the anisotropy of the reinforcement and the location of the gates. Paper D presents an analysis of the non-uniform flow at the flow front during impregnation of a stack of fabrics consisting of layers with different flow resistance. A detailed derivation of the theory and an analytical solution to the equations are presented in an addendum to Paper D. The theoretical model is compared with experimental results and is found to describe the experiment qualitatively well. The resulting permeability of a stack of different fabrics is derived from the basic equations and is found to be a weighted average of the permeability in the individual layers. This result is compared with experiments with different stacking sequences and it is found that the stacking sequence has no influence on the resulting permeability as expected from the theory. Experimental results in excellent agreement with Darcy's law are also presented for the case with radial flow and with unidirectional flow. Finally, Paper E is a theoretical study of the curing behaviour of thick laminates. A general solution independent of the cure kinetic model is derived. The solution is valid for low exothermal peak temperatures and it is characterised by two dimensionless numbers. The first parameter is the ratio between the time scales for the reaction and for heat conduction, the second parameter is the ratio between the processing temperature and the adiabatic temperature rise. The general solution is specialised to a second order autocatalytic cure model so that the results can be compared to numerical results. The agreement between the numerical and the analytical solution is excellent for small exothermal peak temperatures, as expected. The particular model used also serves as an example of the additional dimensionless parameters that are introduced by a specific kinetic model. / <p>Godkänd; 1993; 20070426 (ysko)</p>

A basic understanding of fluid flow through a porous media facilitates a comprehensive understanding of internal erosion in embankment dams. Hence, it is necessary to reveal the detailed seepage flow, the flow-induced forces acting within the porous media and the fluid flow deformation of the porous media. In order to increase the knowledge of the fluid flow a Computational Fluid Dynamics approach is applied to investigate different flow regimes. The regimes ranges from creeping flow, where a Darcy law formulation is sufficient, via an inertia dominated region, where a non-linear term must be added to the Darcy's law such as the Ergun equation, to the turbulent region, where the full Navier-Stokes equations must be solved including a Reynolds decomposition. Since it is not obvious when these transitions takes place the CFD-simulations are used to calculate the apparent permeability, the Blake-type friction factor and the normal and shear forces for a variety of model geometries. This includes quadratic and hexagonal packing of cylinders as well as spheres. One result is that the Reynolds number, where inertia-effects become significant, varies with the packing and the porosity. For a quadratic arrangement of cylinders this occurs around a Reynolds number about 10 while for a hexagonal arrangement it takes place between 30 and 50 depending on the porosity. Another result is that for quadratic arrangement the turbulent set-up at high Reynolds number gives higher forces than a corresponding laminar set-up regardless of the porosity. For hexagonal packing a turbulent set-up can, however, give lower forces. These ranges, regarding the Reynolds number, have been utilized in order to develop an expression for theoretical limits of the effective diameter and the applied pressure gradient to be applied when designing down-scaled geotechnical experimental setups. Regarding the deformation of the porous media there are several methods that has the potential to model the internal erosion process. One way is a mesh deformation approach where the normal and shear forces acting on the particles generate the motion. This methodology requires that the computational mesh is upgraded in every time-step resulting in rather computational heavy simulations. Another way is to combine CFDsimulations of flow in the vicinity of single particles with Monte-Carlo simulations of a system of a large number of particles by using the fact that the distribution of the stream function follows the known principle of minimal dissipation rate of energy. Main result is that the more compact the system is the larger is the possible relative change of permeability by applying a high flow rate. When applying this technique on a classical geotechnical experimental setup, the No Erosion Filter test, results indicate that the developed model captures the main characteristics of the sought particle transportation, both for a sealing as well as a non-sealing design of the filter and fine combination. / För en övergripande förståelse av inre erosion i fyllnadsdammar är det viktigt att få en grundläggande förståelse av villkoren för flöde genom porösa material. Därför är det nödvändigt att belysa de detaljerade flödesförhållandena, flödesinducerade krafter som verkar inom porösa material och flödesinducerad deformering av porösa material. För att öka kunskapen om dessa flöden är "Computational Fluid Dynamics" -simuleringar ett lämpligt tillvägagångssätt att använda för att undersöka olika flöden. Dessa villkor ger upphov till olika flödesregimer allt från krypande flöde, där en formulering baserad på Darcy's lag är tillräcklig, via en region dominerad av tröghetseffekter, där en icke-linjär term måste läggas till Darcy's lag såsom är fallet i Ergun's ekvation, till den turbulenta regionen, där de fullständiga Navier - Stokes ekvationer måste lösas. Men när dessa övergångar sker är inte uppenbart, därav användandet utav CFD-simuleringar för att beräkna den skenbara permeabilitet, en friktion faktor av Blake-typ och de normala och skjuvkrafter för olika modellgeometrier. Detta inkluderar kvadratiska och hexagonala packningar av cylindrar samt sfärer. Ett resultat är att Reynoldstalet där tröghetseffekterna blir betydande, varierar med packning och porositet. För en kvadratisk packning av cylindrar inträffar detta runt ett Reynolds tal omkring 10 medan för en hexagonal packning äger den rum mellan 30 och 50 beroende på porositet. Ett annat resultat är att för kvadratisk packning med turbulenta inställningar genereras högre krafter vid höga Reynolds tal än en motsvarande laminär inställning och detta sker oavsett porositet. För hexagonal packning kan en turbulent inställning ge lägre krafter. Dessa flödesregimer har använts för att fastställa ett matematiskt uttryck för de teoretiska gränserna gällande den effektiva diametern och lämplig tryckgradient för design utav nedskalade geotekniska experiment.När det gäller deformering utav ett poröst material finns flera metoder som har potential att modellera den inre erosions processen. Ett sätt är en nätdeformationsmetod där normal och skjuvkrafter som verkar på partiklarna genererar rörelse utav det porösa materialet. Denna metod kräver att beräkningsnätet uppdateras i varje tidssteg vilket genererar ganska beräkningsintensiva simuleringar. Ett annat tillvägagångssätt är att kombinera CFD-simuleringar utav flödet i närheten av enstaka partiklar med Monte Carlosimuleringar på ett större system med partiklar. De beräknade parametrarna kombineras på det större systemet där minimering utav dissipationen ger oss ett linjärt ekvationssystem med avseende på strömfunktionen. Från strömfunktionen beräknas fördelningen av krafter på strukturen som ger upphov till en omfördelning av partiklarna, detta för att kunna förutse förändringar i permeabiliteten hos det stora systemet av partiklar. Huvudresultatet är att ju mer kompakt systemet är desto större är den möjliga relativa förändringen utav permeabilitet genom att tillämpa ett högt flöde. Om man tillämpar denna teknik på ett klassisk geotekniskt experiment, No Erosion Filter test, så indikerar resultaten att metoden beskriver huvuddragen vad gäller transport utav partiklar i ett poröst material bestående utav en zon med fint material som kopplar till en filter zon. / <p>Godkänd; 2009; 20091019 (gunhel); DISPUTATION Ämnesområde: Strömningslära/Fluid Mechanics Opponent: PhD/Associate Professor Thanasis D. Papathanasiou, University of Thessaly, Grekland Ordförande: Professor Staffan Lundström, Luleå tekniska universitet Tid: Fredag den 20 november 2009, kl 09.00 Plats: E 243, Luleå tekniska universitet</p>

The solar wind interaction with the terrestrial magnetosphere is a source for many spectacular phenomena on or close the Earth's surface. A key question during the last fifty years have been how the solar wind plasma can enter the terrestrial magnetic shield represented by the magnetosphere and its outermost layer called the magnetopause. This have been the seed for many controversies among researchers throughout the years. Today we know that there are several possibilities for the solar wind to break through the magnetic boundary of the Earth. The main plasma transport mechanism at the magnetopause is called magnetic reconnection, where the magnetic energy stored in the solar wind is converted to kinetic energy through a localized break-down of the ideal frozen-in condition of the magnetic field within the plasma. Since its introduction to the space-physical community in the late 1950's, reconnection research have had its primary focus on understanding the onset mechanisms inside the diffusion region where the solar wind magnetic field is reconnected with the magnetospheric magnetic field. In this thesis work we put the context well out of the diffusion region and focuses on the implications of magnetic reconnection onto the surrounding solar wind plasma, rather than on the main mechanisms which initiates the process. We present solutions for the structure of the plasma flow through the magnetopause surface during conditions of ongoing reconnection. This is done through viscous-resistive reconnection models together with models where finite gyro-radius effects are considered. In order to validate the viscous-resistive model we also couple the analytical solutions with \textit{in situ} measurements made by the Cluster spacecraft fleet. This results in an entirely new way of determining the magnetopause transition layer thickness and the location of the reconnection site from spacecraft data. / Godkänd; 2007; 20070904 (pafi)