Measurement of three-dimensional convective flows by digital light field photography
Convective transport processes are the main mechanism of heat transfer in various natural and industrial processes. Examples are oceanic or atmospheric currents as well as various applications in energy and chemical engineering.
The design, analysis and optimization of related applications rely on accurate numerical simulations of these processes using simplified physical models. In order to yield reliable results, these models have to be validated through experimental data. Thereby it is ensured, that all properties of the problem are correctly incorporated in the employed model and valid assumptions have been made for simplification.
A complete experimental description of a flow field would be given through the determination of the velocity field, describing the three spatial velocity components at each point of the flow, and the temperature field, providing local flow temperatures. Throughout the years, various experimental techniques have been developed in order to achieve best possible resolutions of these flow properties. Hereby, a major factor limiting the choice of appropriate experimental methods is the demand for non-invasiveness. Therefore, various traditional methods for the measurement of flow velocities and temperatures are inherently not applicable and more advanced methods like particle image velocimetry (PIV) have been developed.
Recent developments in the field of optics and in particular in the field of light field imaging allow for new approaches to the experimental characterization of three-dimensional flow phenomena. With the light field imaging technique, a single camera is able to capture an object’s position in all three spatial dimensions. This possibly simplifies the setup and calibration of PIV experiments in comparison to state of the art methods like tomographic PIV or holographic PIV.
In this context, the aim of the research project is the application and testing of light field imaging as an innovative approach for the experimental investigation of convective flow phenomena. A major work package is the assessment of the possibilities and limits of the measurement technique by comparison with existing methods.
The application to concrete problems in the area of convective transport processes also takes place in the framework of the following projects:
- „Measurement of boundary layer profiles to predict mixed convection losses on solar tower power plants”
- „Three-dimensional measurement of flow fields in glaciology and urban climatology by means of light field photography"