Berlin 2008 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 25: Fluid dynamics I

DY 25.1: Talk

Thursday, February 28, 2008, 11:30–11:45, MA 001

Highly resolved measurements of temperature fluctuations in turbulent flows — •Achim Kittel and Florian Heidemann — Energy and Semiconductor Research Laboratory, University of Oldenburg,

We present high frequency, highly spatially resolved temperature measurement taken with a sub-micrometer thermocouple developed in our group gained from two different experimental setups. The first setup is a water free-jet in water. Here a heated water jet is injected into a cold basin. The presented measurements are taken at high injection velocities and, therefore, the temperature has no impact on the flow --- it can be considered as a passive scalar. The temperature fluctuations are taken at different positions and analyzed with different methods. With our sensor we are able to resolve temperature fluctuations up to 30kHz under these conditions. The changes on characteristic features of the inertial range are investigated under variation of the sensors position. The second experiment is a large scale convection experiment --- the barrel of Ilmenau. Here the mean temperature and the temperature fluctuations are measured as a function in distance to the cooling plate at the top lid of the experiment. We achieved a special resolution of a micrometer in separation from the lid. The results are discussed by means of finite element simulation.