In the quest for a high fidelity numerical scheme for CFD it is necessary to satisfy demands on accuracy, conservation, positivity and upwinding. Recently the requirement of rotational invariance has been added to this list. In the present work we are mainly interested in upwinding and rotational invariance of Least Squares Kinetic Upwind Method (LSKUM). The standard LSKUM achieves upwinding by stencil division along co-ordinate axes which is referred to as co-ordinate splitting method. This leads to symmetry breaking and rotational invariance is lost. Thus the numerical solution becomes co-ordinate frame dependent. To overcome this undesirable feature of existing numerical schemes, a new algorithm called KUMARI (Kinetic Upwind Method Avec Rotational Invariance, 'Avec' in French means 'with') has been developed. The interesting mathematical relation between directional derivative, Fourier series and divergence operator has been used effectively to achieve upwinding as well as rotational invariance and hence making the scheme truly or genuinely multidimensional upwind scheme. The KUMARI has been applied to the test case of standard 2D shock reflection problem, flow past airfoils, then to 2D blast wave problem and lastly to 2D Riemann problem (Lax's 3rd test case). The results show that either KUMARI is comparable to or in some cases better than the usual LSKUM.

Dans le cadre de la recherche de solutions visant à réduire les consommations d’énergie liées au rafraîchissement des bâtiments, une plateforme d’essais a été mise en place en 2012 à l’I2M et installée sur le site de l’IUT de l’Université de Bordeaux. Cette plateforme est issue d’un prototype de bâtiment BEPos, dénommée Sumbiosi, réalisée par un consortium rassemblé autour du campus de Bordeaux dans le cadre de sa participation à la compétition interuniversitaire du Solar Decathlon Europe 2012. Elle a notamment été conçue de façon à favoriser le stockage passif d’énergie diurne en hiver et le déstockage semi-passif d’énergie nocturne en été. Deux éléments principaux permettent a priori ces fonctions de stockage et déstockage passifs d’énergie : une dalle de forte masse thermique située du côté de la façade Sud vitrée du bâtiment, et des protections solaires et ouvertures pilotables sur les façades Sud, Nord et en lanterneau du bâtiment ; ces dernières assurent les trois principes fondamentaux en ventilation naturelle qui ont lieu grâce aux effets du tirage thermique et de la force du vent. L’objet des travaux menés actuellement ont pour objectif initial d’appréhender qualitativement le stockage-déstockage d’énergie dans la dalle, celle-ci étant soumise à des échanges radiatifs (extérieur et d’intérieur) et convectifs (générés par convection naturelle, forcée ou mixte). Ils visent par la suite à caractériser précisément et quantitativement le couplage entre ce stockage-déstockage, et les circulations d’air et apports radiatifs constatés. La mise en place d’une modélisation, reliant l’ensemble de ces paramètres est envisagée, dans le but d’avancer vers une loi de pilotage de ces éléments mobiles amenant à des conditions de confort internes au bâtiment optimales. Cette dernière doit nous permettre de montrer qu’un choix adéquat de stratégie de ventilation permet une minimisation de consommations électrique en évitant autant que possible le recours à la climatisation. Pour atteindre cet objectif, la démarche scientifique adoptée a consisté à mettre en évidence le rôle de la dalle en béton dans stockage/déstockage d’énergie thermique, sous l’effet de différents scénarii de ventilation naturelle de la plateforme. Cette dalle a été instrumentée, de façon discrète sur l’ensemble de sa surface, en termes de capteurs de flux de chaleur (Peltier et Captec), de températures (thermocouples T), et de la vitesse d’air proche de la dalle. Les premiers résultats, obtenus en période estivale, mettent clairement en évidence le couplage entre les phénomènes de stockage et déstockage d’énergie quotidiens et le cycle météorologique correspondant, ceci pour divers scénarii de pilotage des éléments mobiles de l’enveloppe du bâtiment (persiennes, ouvertures). / As part of the search for solutions to reduce the energy consumption related to the refreshment of buildings, a test platform was set up in 2012 at the I2M and installed on the IUT site of the " University of Bordeaux. This platform is the result of a prototype of a PEHs building called Sumbiosi, carried out by a consortium gathered around the Bordeaux campus as part of its participation in the inter-university competition of the Solar Decathlon Europe 2012. It was conceived in such a way as to favor the passive storage of diurnal energy in winter and the semi-passive destocking of nighttime energy in summer. Two main elements allow a priori these functions of passive storage and retrieval of energy: a slab of high thermal mass located on the side of the glazed south facade of the building, and solar protections and openings controllable on the facades South, North and skylight of the building ; the latter provide the three fundamental principles of natural ventilation, which take place through the effects of thermal draft and wind force. The object of the work currently carried out has the initial objective of qualitatively understanding the storage and de-stocking of energy in the slab, the latter being subjected to radiative (external and internal) and convective exchanges (generated by natural convection, forced or mixed). They are intended to characterize precisely and quantitatively the coupling between this storage and release, and the circulations of air and radiative contributions observed. The implementation of a modeling, linking all these parameters is envisaged, with the aim of advancing towards a law controlling these mobile elements leading to optimum internal comfort conditions for building. The latter must enable us to show that an adequate choice of ventilation strategy allows a minimization of electrical consumption by avoiding the use of air conditioning as much as possible. To achieve this objective, the scientific approach adopted consisted in highlighting the role of the concrete slab in the storage / destocking of thermal energy, under the effect of different scenarios of natural ventilation of the platform. This slab was instrumented, discretely over its entire surface, in terms of heat flux sensors (Peltier and Captec), temperatures (T thermocouples), and air speed close to the slab. The first results, obtained during the summer period, clearly show the coupling between the phenomena of daily energy storage and destocking and the corresponding meteorological cycle for various scenarios controlling the moving elements of the building envelope (shutters, openings).

För att skapa ett bra inomhusklimat i flerbostadshus ställs höga krav på ventilationssystemet för att ta hand om den fukt som skapas. Det finns således anledning att undersöka om Boverkets byggreglers krav för minsta luftflöde är tillräckligt ur fuktsynpunkt. Syftet är att uppmärksamma problem med ökande fukttillskott i nyproducerade flerbostadshus vilket skulle kunna förändra projekteringen av ventilation i framtiden. För att kunna undersöka om Boverkets byggreglers krav är tillräckligt ur fuktsynpunkt analyseras relativ fuktighet och fukttillskott i fyra flerbostadshus i Jönköping. Det framgår att flera lägenheter erhöll höga värden för fukttillskott och relativ fuktighet vilket kan skada byggnaden och påverka människors hälsa. Boverkets byggreglers krav för minsta luftflöde var otillräckligt ur fuktsynpunkt i flera av de undersökta flerbostadshusen. / To create a good indoor climate in apartment buildings, high demands are made on the ventilation system to take care of the moisture that is created. There is therefore reason to investigate if Boverket, the Swedish National Board of Housing, Building and Planning, requirements for minimum airflow are sufficient from a moisture point of view. The purpose is to rise awareness about increasing additional moisture in newly built apartment buildings, which could change the project planning of ventilation systems in the future. In order to investigate whether requirements of the Boverket building regulations are sufficient from a moisture point of view, relative humidity and additional moisture were analyzed in four apartment buildings in Jönköping. Several apartments received high values of additional moisture and relative humidity which could damage the building and affect human health. The requirements of Boverket building regulations for minimum airflow should therefore be reviewed.

The goal of this master thesis is to create a simplified model of an actual swirl diffuser using CFD (Computational Fluid Dynamics) simulation, so that it would be easy to calculate (would have a simple geometry, a proper mesh and would enable quick definition of the model’s boundary conditions) and would also create an airflow pattern in space as close to reality as possible. In the process a CFD model with a certain geometry was created. Subsequently, various model settings were tested. Calculation results were compared with the results of the experimental measurement done using the PIV method.

The diploma thesis deals with CFD simulating the air flow inside the car using the numerical calculation program Star-CCM+. The aim of the thesis was to prepare 3D geometry, resp. realistic model of the real car, preparing boundary conditions including material properties, simulating the steady state of the environment and evaluating the speed and temperature of the car cabin. The paper presents the results of the temperature distribution and air velocities in the cabin during the winter, spring and summer conditions in HVAC on and HVAC off modes. The monitored air temperatures and surface temperatures of the car parts are compared with the measured data. The average difference between simulation and measurement was at air temperatures of 2.3 °C and surface temperatures of 3.4 °C.

L'objectif de cette thèse est de réaliser une étude approfondie sur la vélocimétrie par suivi 3D de particules (3D Particle Tracking Velocimetry, 3D PTV) pour l'air intérieur convective thermique. Ce travail se concentre principalement sur l'étude de la littérature, l'évaluation des performances des algorithmes de mesure de la 3D PTV, et l'étude expérimentale pour l'air intérieur convective thermique en utilisant la technologie 3D PTV. Tout d'abord, la technologie 3D PTV typique et ses principales applications précédentes pour l'étude de d'air intérieur sont examinés. Ensuite, les performances de différents algorithmes de mesure de la 3D PTV sont évalués numériquement et expérimentalement. Deux sections se compose de cette partie, on est de comparer les performances de mesure de l'algorithme de PIV typique et l'algorithme de 3D PTV, une autre est de comparer les performances des sept algorithmes complets de 3D PTV. Enfin, sur la base de l'analyse présentée dans la thèse, l'étude expérimentale de l'écoulement d'air intérieur généré par la méthode de ventilation mélange est réalisée / The objective of this thesis is to conduct a comprehensive study on 3D Particle Tracking velocimetry (PTV) for thermal convective indoor airflow. This work mainly concentrates on the literature survey, the performance evaluation of 3D PTV measurement algorithms, and the experimental investigation for thermal convective indoor airflow using 3D PTV measurement technology. First, typical 3D PTV technology and its main previous applications for indoor airflow study are carefully reviewed. Then, the performances of different 3D PTV measurement algorithms are evaluated numerically and experimentally. Two sections consist of this part, one is to compare the measurement performances of typical PIV algorithm and 3D PTV algorithm, another is to compare the performances of seven complete 3D PTV algorithms. Last, based on the analysis in the thesis, the experimental investigation for indoor airflow generated by mixing ventilation method is conducted

La ventilation nasale est vitale pour le nouveau-né, respirateur nasal exclusif. Le tiers antérieur des fosses nasales peut être modifié par une sténose congénitale de l’orifice piriforme, tandis leur partie postérieure peut être fermée par une atrésie choanale uni ou bilatérale ou par des lésions du nasopharynx.Les simulations numériques permettent d’analyser l’écoulement et le conditionnement de l’air en contournant les limites techniques et éthiques rencontrées in vivo. Devant la rareté des données dans la littérature, une étude de faisabilité a été nécessaire et concluante : les modèles numériques sont qualitativement proches de la réalité. Un travail sur les conditions physiologiques chez le nouveau-né a ensuite été réalisé, avec une méthodologie retravaillée. La reconstruction tridimensionnelle des fosses nasales est possible dès la naissance. La création d’une sphère centrée sur la pointe du nez, éloignant le domaine d’entrée de la zone d’intérêt, a permis d’analyser le rôle du tiers antérieur des fosses nasales.La valve nasale joue un rôle majeur en inspiration : perte de charge, accélération, guidage des flux et réchauffement de l’air. Les trois quarts du réchauffement ont lieu en amont du cornet inférieur. Une obstruction nasale entraîne une réduction des vitesses et une augmentation des températures de l'air. La simulation de l’inspiration d’air à 0°C a permis de constater que les fosses nasales permettent d’amortir les effets du refroidissement de l’air extérieur.Ce travail constitue une première approche de la physiologie de la ventilation nasale du nouveau-né par modélisation numérique, indispensable à la compréhension de la pathologie nasale néonatale. / Nasal breathing is essential for the newborn, exclusive nasal breather. The anterior third of the nasal fossae may be modified by a congenital stenosis of the pyriform aperture, while their posterior part may be closed by unilateral or bilateral choanal atresia.Numerical simulations are a good means to analyze airflow and air-conditioning: they circumvent the technical and ethical limits encountered in vivo. Given the rarity of available data in the literature, a feasibility study was necessary and was conclusive: numerical models are qualitatively close to reality. A work on the physiological conditions in newborns was conducted, using refined methodology. The three-dimensional reconstruction of the nasal fossae is possible from birth. The creation of a sphere centered on the tip of the nose, moving the boundary conditions away from the area of interest, made it possible to analyze the role of the anterior third od the nasal fossae.The nasal valve plays a major in inspiration: it is a zone of pressure loss, acceleration, flow guidance and air warming. Three-fourths of the warming takes place upstream the inferior turbinate. A partial nasal obstruction modifies these results with lower velocities and higher temperature of the air. The simulation of the inspiration of cold air (0°C) has shown that the nasal fossae can dampen, without canceling, the effects of air cooling. This work is a first approach to the physiology of nasal ventilation of the newborn by numerical modeling, which is essential to the understanding of neonatal nasal pathology.

Surgical site infection is responsible for 38 percent of reported infections after surgery. This infection increases mortality and treatment costs, and prolongs the hospitalization of patients. Bacteria-carrying particles are the main cause of surgical site infection and one of the main sources of these particles is skin fragments released from the surgical personnel during an ongoing surgery. Ventilation systems reduce the concentration of bacteria-carrying particles by supplying clean air in the operating room. The performance of operating room ventilation systems is affected by internal disruptions such as medical equipment, surgical lamps, number of staff and their behaviour during the surgery. Using computational fluid dynamics, this thesis investigates the airflow behaviour and distribution of the contamination in the operating room under the presence of various internal disruptions. In this regard, three common ventilation systems are considered: laminar airflow, turbulent mixing and temperature-controlled airflow ventilations. This study tries to overcome the weaknesses of the ventilation systems by providing sustainable solutions and continuously being in contact with design companies. It is common to use warming blankets to prevent reduction in the core body temperature of the patient during major surgeries. However, there is a major concern that these blankets disrupt the supplied airflow, which results in rising contaminant concentration. Most of the studies about warming blankets are clinical works and it is still not clear whether or not these blankets should be used. The results of the present study show that using warming blankets had no impact on increase of contamination level at the surgical zone. However, one common type of warming blanket – a forced-air warming blanket – can considerably increase the concentration of bacteria-carrying particles at the wound area if it becomes contaminated. The simulated results of the airflow field and particle tracking showed that the laminar airflow ventilation system was disturbed more easily by the local heat loads than overall heat loads in the operating room. Surgical lamps are considered as an obstacle in the supplied airflow path. These lamps create a stagnant area above the operating table and increase the contamination level. In this regard, a novel design of surgical lamp, a fan-mounted surgical lamp, was introduced to operating rooms.This device was used in the operating rooms equipped with laminar airflow and mixing ventilation system. The simulated results revealed that this lamp significantly reduced the contamination level at the operating table. Visualization techniques were adopted to teach and improve the understanding of surgical personnel about transmission of contaminated particles in operating rooms. Here, a virtual and augmented reality interface was used to visualize the impact of differences in ventilation principle, surgical staff constellation and work practice. / Infektioner relaterade till kirurgiskt ingrepp utgör 38 % av rapporterade infektioner efter operation. Dessa infektioner ökar dödligheten och behandlingskostnaderna samt förlänger patienternas sjukhusvistelse. Bakteriebärande partiklar är den främsta orsaken till infektion vid kirurgi. Huvudkällan till dessa partiklar är hudfragment som frigörs från kirurgisk personal under en pågående operation. Genom att tillföra ren luft via ventilationssystemet kan koncentrationen av baktebärande partiklar i operationssalen minskas. Ventilationssystemets förmåga att ventilera salen påverkas av föremål som stör luftströmmen, som exempel medicinsk utrustning, kirurgiska lampor samt av närvarande personal och deras beteende under operationen. Med avancerade numeriska strömningsberäkningar undersöks i denna avhandling luftflöden och fördelningen av föroreningar i operationssalen under inverkan av sådana störningar. Tre olika ventilationssystem inkluderas. Ett för laminärt luftflöde, ett för turbulent omblandning och ett för temperaturreglerad luftströmning. I studien kartläggs ventilationssystemens funktion och relevansen prövas i ett kontinuerligt samarbete med tillverkande industri. Användning av värmefiltar förekommer under större operationer för att hålla patientens kroppstemperatur stabil. Det finns emellertid en stor oro för att dessa filtar stör det tillförda luftflödet och därmed ökar föroreningsnivån. En vanlig typ av värmefilt med forcerad varmluft kan om den är förorenad avsevärt öka koncentrationen av bakteriebärande partiklar i sårområdet. De flesta undersökningar om värmande filtar är kliniska studier och det är fortfarande inte helt klarlagt i vilken mån och hur dessa filtar skall användas. Denna studie visar emellertid att användning av värmefiltar inte påverkar föroreningsnivån i den kirurgiska zonen. Gjorda datorsimuleringar av luftflödesfältet och partikelspårning visar att det laminära ventilationsflödet lättare störs av lokala värmebelastningarna än av generella värmebelastningar i operationssalen. Kirurgiska lampor betraktas som hinder i en planerad luftflödesväg. Lampor kan skapa en stillastående luftmassa ovanför operationsbordet och därmed öka föroreningsnivån. För detta introduceras en ny design av kirurgisk lampa, en fläktmonterad kirurgisk lampa för operationsrum, utrustade med laminärt luftflöde och omblandning. Simulerade resultat visar att denna nya kirurgiska lampa signifikant minskar föroreningsnivån vid operationsbordet. Visualiseringsteknik användes i denna studie för att förbättra förståelsen hos kirurgisk personal om hur förorenade partiklar kan spridas i operationssalen. Med ett virtuellt och förstärkt gränssnitt visualiserades föroreningshalter i rumsluften då olika typer av ventilationssystem användes. Visualiseringen visar också hur kirurgigruppens storlek och arbetsställning under operation påverkar spridningen av föroreningar. / <p>QC 20201103</p>

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