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The potential of flexible micro pillars for measuring near wall flow phenom- ena was theoretically and experimentally investigated. The bending of the micro pillars is a measure for the local wall shear stress (WSS) or a visualisa- tion of near wall flow phenomena. Polydimethylsiloxane (PDMS) was chosen as material for the sensor. Within the thesis the experimental work with the shear stress sensor mainly has the focus on the transition to turbulence. Closely connected are improvements of the measurement techniques. The transition is thereby investigated qualitatively and quantitatively. Another huge part of the thesis was the improvement of the reliability of the manu- facturing process of the micro pillars. For this purpose new manufacturing methods for single pillars and pillar arrays have been tested. Further on, dif- ferent detection methods for capturing the bending of the pillar were tested, too. The measurements of the transitional flow were performed at flat plate boundary layer in an oil channel. Ondina 913 was used as test fluid. The physical properties of the PDMS changed dramatically while longer exposed to Ondina 913. Hence, it was unfeasible to receive reproducible quantita- tive results. Better results were achieved if the pillars are used as flexible micro tufts revealing the flow and WSS topology directly at the wall quali- tatively. With the pillar sensor it was possible to detect turbulent spots in the transitional state of the flat plate boundary layer. Furthermore, coherent structures and their typical sign in the viscous sublayer could be identified and the occurrence of critical points and back flow could be experimentally verified.

Most of the old oil fields in China have reached high water cut stage, in order to meet the booming energy demanding, oil production rate must be kept in the near future with corresponding IOR (Improving Oil Recovery) methods. Z106 oilfield lies in Shengli Oilfields Area at the Yellow River delta. It was put into development in 1988. Since the oil belongs to heavy oil, the oil-water mobility ratio is so unfavourable that water cut increases very quickly. Especially for reservoir Ng21, the sand rock is sediment from river channel, the permeability heterogeneity and heavy oil properties together lead to extremely poor water flooding efficiency. In order to improve the oil recovery, IOR methods are needed urgently. Considering all practical situations for this reservoir and present technique level, polymer flooding method has been selected as an IOR test with numerical simulation. For polymer flooding, since polymer resolution has the capability of enlarging water viscosity, it controls the mobility of water phase and at the same time improves the driving efficiency. During polymer flooding simulation, many factors must be taken into account for the construction of mathematical model, such as inaccessible pore volume, polymer shear thinning effect, polymer adsorption, relative permeability reduction factors, etc. All simulations were done with black oil model with polymer option in ECLIPSE. Simulation results for a theoretical river channel reservoir with serious permeability heterogeneity and heavy oil, and simulation results for practical reservoir Ng21, both have shown that polymer flooding is a feasible method for IOR. For reservoir Ng21, with polymer slug size of 0.235 PV, polymer concentration at 1.5 kg/m3, the final oil recovery after polymer flooding could reach 12.8%, the enhanced oil recovery is about 5%. If only the developable oil reserve being taken into account, the final oil recovery is about 34%, and enhanced oil recovery from polymer flooding is more than 12%. For such heavy oil river channel reservoir to reach such a final oil recovery, it could be concluded as a great success. Since there are still many such oil reservoirs in Shengli Oilfields Area, polymer flooding will be of great importance for improving oil recovery in this area in the near future.

The thesis describes state of the art volumetric measurement techniques and applies a 3D measurement technique, 3D Scanning Particle Tracking Velocimetry, to the transitional backward facing step flow. The measurement technique allows the spatial and temporal analysis of coherent structures apparent at the backward facing step. The thesis focusses on the extraction and interaction of coherent flow structures like shear layers or vortical structures.

Most of the old oil fields in China have reached high water cut stage, in order to meet the booming energy demanding, oil production rate must be kept in the near future with corresponding IOR (Improving Oil Recovery) methods. Z106 oilfield lies in Shengli Oilfields Area at the Yellow River delta. It was put into development in 1988. Since the oil belongs to heavy oil, the oil-water mobility ratio is so unfavourable that water cut increases very quickly. Especially for reservoir Ng21, the sand rock is sediment from river channel, the permeability heterogeneity and heavy oil properties together lead to extremely poor water flooding efficiency. In order to improve the oil recovery, IOR methods are needed urgently. Considering all practical situations for this reservoir and present technique level, polymer flooding method has been selected as an IOR test with numerical simulation. For polymer flooding, since polymer resolution has the capability of enlarging water viscosity, it controls the mobility of water phase and at the same time improves the driving efficiency. During polymer flooding simulation, many factors must be taken into account for the construction of mathematical model, such as inaccessible pore volume, polymer shear thinning effect, polymer adsorption, relative permeability reduction factors, etc. All simulations were done with black oil model with polymer option in ECLIPSE. Simulation results for a theoretical river channel reservoir with serious permeability heterogeneity and heavy oil, and simulation results for practical reservoir Ng21, both have shown that polymer flooding is a feasible method for IOR. For reservoir Ng21, with polymer slug size of 0.235 PV, polymer concentration at 1.5 kg/m3, the final oil recovery after polymer flooding could reach 12.8%, the enhanced oil recovery is about 5%. If only the developable oil reserve being taken into account, the final oil recovery is about 34%, and enhanced oil recovery from polymer flooding is more than 12%. For such heavy oil river channel reservoir to reach such a final oil recovery, it could be concluded as a great success. Since there are still many such oil reservoirs in Shengli Oilfields Area, polymer flooding will be of great importance for improving oil recovery in this area in the near future.

The potential of flexible micro pillars for measuring near wall flow phenom- ena was theoretically and experimentally investigated. The bending of the micro pillars is a measure for the local wall shear stress (WSS) or a visualisa- tion of near wall flow phenomena. Polydimethylsiloxane (PDMS) was chosen as material for the sensor. Within the thesis the experimental work with the shear stress sensor mainly has the focus on the transition to turbulence. Closely connected are improvements of the measurement techniques. The transition is thereby investigated qualitatively and quantitatively. Another huge part of the thesis was the improvement of the reliability of the manu- facturing process of the micro pillars. For this purpose new manufacturing methods for single pillars and pillar arrays have been tested. Further on, dif- ferent detection methods for capturing the bending of the pillar were tested, too. The measurements of the transitional flow were performed at flat plate boundary layer in an oil channel. Ondina 913 was used as test fluid. The physical properties of the PDMS changed dramatically while longer exposed to Ondina 913. Hence, it was unfeasible to receive reproducible quantita- tive results. Better results were achieved if the pillars are used as flexible micro tufts revealing the flow and WSS topology directly at the wall quali- tatively. With the pillar sensor it was possible to detect turbulent spots in the transitional state of the flat plate boundary layer. Furthermore, coherent structures and their typical sign in the viscous sublayer could be identified and the occurrence of critical points and back flow could be experimentally verified.

Für die effektive numerische Berechnung von Strömungsphänomenen im frühen Entwicklungsprozess wurde methodisch das Zusammenwirken verschiedener Berechnungstools hinsichtlich der Berechnungsdauer und Güte auf handelsüblichen Desktoprechnern untersucht. Dabei ist die Skalierbarkeit der Berechnungsmodelle auf unterschiedliche geometrische Skalen sowie die Umsetzungsmöglichkeit der Berechnung kombinierter Fluidphasen essenziell. Für die Umsetzung wurden erste Grundlagenuntersuchungen an einfachen Geometrien experimentell und virtuell durchgeführt sowie die Ergebnisse gegenübergestellt. Daraus konnten Anforderungen abgeleitet und bereits im Ausschlussverfahren für das Projekt ungeeignete Software detektiert werden. Weiterhin wurden die Simulationsparameter, aufbauend auf den Grundlagenuntersuchungen, an die komplexen Geometrien von Bauteilen/Baugruppen bis hin zum Viertelfahrzeug angepasst. Somit konnten für die jeweiligen Berechnungstools die Stärken hinsichtlich der Anforderungen an die Geometrie und die physikalischen Randbedingungen abgeleitet werden. Anschließend wurde eine Software entwickelt, welche automatisiert Ergebnisse unterschiedlicher Softwarelösungen und geometrischer Skalen verarbeitet, interpoliert und anschließend auf gewählten Schnittstellen bereitstellt. Somit lassen sich die effektivsten Berechnungsmethoden miteinander verknüpfen. Zudem konnte im Laufe der Bearbeitungszeit eine Software (PreonLab) zum Einsatz kommen, welche hinreichend genau und dennoch zeitlich effektiv komplexe Strömungsphänomene berechnen kann. Im Zuge der Projektbearbeitung konnten somit Anforderungen als auch Randbedingungen für die numerische Berechnung komplexer Strömungsphänomene am Gesamtfahrzeug beschrieben werden.

Despite the increasing popularity of high-order methods in computational fluid dynamics, their application to practical problems still remains challenging. In order to exploit the advantages of high-order methods with geometrically complex computational domains, coarse curved meshes are necessary, i.e. high-order representations of the geometry. This dissertation presents a strategy for the generation of curved high-order surface meshes. The mesh generation method combines least-squares fitting with energy functionals, which approximate physical bending and stretching energies, in an incremental energy-minimizing fitting strategy. Since the energy weighting is reduced in each increment, the resulting surface representation features high accuracy. Nevertheless, the beneficial influence of the energy-minimization is retained. The presented method aims at enabling the utilization of the superior convergence properties of high-order methods by facilitating the construction of coarser meshes, while ensuring accuracy by allowing an arbitrary choice of geometric approximation order. Results show surface meshes of remarkable quality, even for very coarse meshes representing complex domains, e.g. blood vessels.