Ce travail de thèse s'intéresse à l'effet d'une variation longitudinale de l'occupation du sol de la plaine d'inondation sur l'écoulement d'une rivière en débordement. Nous traitons le cas d'une transition entre une zone de prairie et une zone de forêt, et vice versa. Cette variation d'occupation du sol est associée à une transition de rugosité hydraulique entre une rugosité de fond (prairie fortement immergée) et des macro-rugosités émergées (arbres), modélisées respectivement par une moquette plastifiée et par un champ de cylindres. Ces écoulements sont étudiés en laboratoire dans un canal de dimension 18 m x 3 m. Dans un premier temps, nous considérons l'écoulement à travers un champ de cylindres émergents en lit simple, en étudiant l'effet du fond sur le sillage des cylindres et le phénomène de seiche (fortes oscillations de la surface libre). Dans un deuxième temps, nous nous penchons sur le développement vers l'uniformité d'un écoulement en lit composé de rugosité uniforme. La croissance asymétrique de la couche de mélange du lit composé, la propriété d'autosimilarité ainsi que l'organisation tridimensionnelle des structures turbulentes cohérentes associées à la couche de mélange sont analysées. Le troisième temps fait l'objet de la transition longitudinale de rugosité en lit composé, dont l'effet sur la couche de mélange et sur les structures cohérentes est discuté. Nous évaluons également les différentes contributions au transfert latéral de quantité de mouvement entre lit mineur et plaine d'inondation par diffusion turbulente, par échange de masse et par les courants secondaires / This PhD thesis investigates the effect of a longitudinal change in floodplain land use on an overflooding river flow. We consider a transition between a meadow and a woodland and vice versa. This change in land use is associated with a change in hydraulic roughness, between a bed roughness (highly submerged meadow) and emergent macro-roughnesses (trees), respectively modelled by a plastic artificial grass and an array of emergent cylinders. The flows are experimentally investigated in an 18 m x 3 m laboratory flume. In a first step, we investigate the flow through a cylinder array in a single channel, focusing on the effect of bed roughness on the cylinder wakes and on the seiche phenomenon (strong free surface oscillations). In a second step, we study the development towards flow uniformity of compound channel flows with a uniform hydraulic roughness on the floodplains. The asymmetrical growth of the compound channel mixing layer, the self-similarity property and the three-dimensional organisation of the turbulent coherent structures associated with the mixing layer are analysed. In a third step, we investigate the longitudinal change in roughness in compound channel configuration, which effects on mixing layer and on coherent structures are discussed. We also assess the contributions to lateral transfers of momentum between main channel and floodplain by turbulent diffusion, by mass exchange and by secondary currents

Aim: To evaluate different parameters potentially affecting the efficacy of air-polishing devices in disinfecting implant surfaces in a non-surgical treatment approach of peri-implantitis lesions. Material and method: Altogether, 56 turned and 56 moderately rough implants were coated with a simulated biofilm. The implants were mounted in customized resin models simulating peri-implant 30° bone-defects, 3- and 5-mm deep; soft tissues were simulated with ballistic gelatin. Each implant was cleaned for 30 or 90 seconds in total (6 sites pr. implant; 5 or 15 seconds pr. site) with one of two different air-polishing devices (W&H and EMS). Implants were photographed in three different angulations and the amount of residual biofilm on the implant surface was measured digitally. Beta-regression models were used to assess the outcome. Results: Implant surface, treatment time and air-polishing device significantly affected the amount of residual biofilm. Turned implant surface, longer treatment time, and using the EMS device resulted in significantly less residual biofilm. In the most apical part of the defect, both air-polishing devices performed similarly, however, this was also the area with most biofilm left compared to more coronal aspects. Defect depth had no significant effect.  Conclusion: Superior biofilm removal is achieved at implants with turned surface, and when applying longer treatment time. At the deepest aspect of the defect, implant decontamination is compromised. / Syfte: Syftet med denna laborativa studie är att utvärdera olika parametrar som potentiellt kan påverka effekten av air-polishing maskiner vid icke-kirurgisk rengöring av implantat för behandling av peri-implantit. Material och metod: Sammanlagt, 56 turned (maskin bearbetade) och 56 moderately rough (måttlig ytråhet) implantat var belagda med en biofilmimitation. Implantaten var placerade i en specialgjord resin-modell som simulerar en 30° bendefektmodell med 3- respektive 5 mm defektdjup; mjukvävnaden simulerades med ballistiskt gelatin. Varje implantat rengjordes i totalt 30 eller 90 sekunder (6 sidor per implantat; 5 eller 15 sekunder per sida) med en av två air-polishing maskiner (W&H och EMS). Implantaten fotograferades sedan ur tre olika vinklar för att digitalt bedöma kvarstående biofilm. Implantatyta, tillverkare, defektdjup och behandlingstid analyserades som prediktionsvariabler för kvarstående biofilm (%). Beta-regressionsanalys användes för att bedöma resultatet. Resultat: Implantat-yta, tillverkare och behandlingstid påverkade mängden kvarvarande biofilmsimulation signifikant. Maskinbearbetade implantatytor, en längre behandlingstid, användande av EMS maskinen, resulterade alla i signifikant mindre kvarvarande biofilm. De två tillverkarna presterade endast lika i de mest apikala delarna av defekten, men detta var också det område med mest kvarvarande biofilm jämfört med mer koronala aspekter. Defekt djup hade ingen signifikant effekt på resultatet. Slutsats: Man kan förvänta sig bättre borttagning av biofilm när man behandlar maskinbearbetade implantatytor samt när man använder en längre behandlingstid.Vid den djupaste aspekten av defekten, äventyras dekontaminering av implantat