Three-dimensional measurement of flow fields in glaciology and urban climatology by means of light field photography
To describe the influence of climate changes the energetic investigation of climatologically relevant systems has gained enormously in importance in recent years. In the climatological research at RWTH this incorporates amongst others the balance of glacial ice, mainly because the impact on the global sea level and water supply is of considerable relevance. Furthermore, urban climatology has become an essential factor in urban planning in order to avoid bio-climatic stresses under changing climatic conditions and to ensure compliance with emission limits.
In both areas - glaciology and urban climatology - the resolution of the local energy balance is crucial. A full investigation and modeling of deglaciation is only possible through a closed energy balance. In urban climatology it is of strong interest, how and how far modern building materials affect the urban climate. The emergence of so-called heat islands in urban areas has health consequences, especially for an aging population. These problems can be more accurately predicted and thus avoided by planning measures, the more accurate the heating of the air can be described by a closed energy balance at the relevant surfaces.
The key to the energy balance is the knowledge of the convective heat transfer from the surface to the surroundings or from the surroundings to the surface. The convective heat transfer depends mainly on the flow conditions of the ambient air, so that the knowledge of the flow velocity is a prerequisite for the energy balance.
In this context, the aim of this project is to develop a measurement methodology for climatological field measurements, which allows to measure three-dimensional air flows within a large measurement volume. This measurement technique is based on the conventional particle image velocimetry (PIV), but uses the novel approach of light field iamging. An existing light field camera (Raytrix R29) at the Institute of Heat and Mass Transfer (WSA) is employed within the framework of this project, which allows to detect the position of a particle in three-dimensional space.