Speaker
Description
We carried out ultrasonic Doppler and power consumption measurements in a 1:6 downscaled water experiment to analyze the potential for dynamo action in a precession driven sodium experiment [1]. The experiments are embedded in the DRESDYN (DREsden Sodium facility for DYNamo and thermohydraulic studies) project devoted to a better understanding of the homogeneous dynamo effect in planets and stars.
First of all a non-axisymmetric Kelvin mode is growing with rising precession ratio, which alone is not suitable for dynamo action in the experiment. In a narrow region of the precession ratio a secondary axisymmetric mode arises. For even higher precession ratios, a strong shear appears at the outer rim of the cylinder and the flow in the bulk becomes completely turbulent. The appearance of the secondary axisymmetric mode promises dynamo action within the sodium experiment under construction [2].
The downscaled water experiment was operated in a wide range from Re=10000 to 1.610*6, showing a very good agreement with direct numerical simulations at their upper limit of Re=10000.
Furthermore, we give an overview of the present state and the commissioning of the DRESDYN facility which is still in progress.
