F/1 Laboratory studies of the form and oscillations towards breakup of falling raindrops in the Mainz Wind Tunnel Miklós Szakáll, Subir K. Mitra, Karoline Diehl, Stephan Borrmann
Objectives Measurement of the time averaged axis ratio of oscillating millimetre size drops with equivalent diameters (Do) above 3 mm Evaluation of the time averaged axis ratio of oscillating drops with equivalent diameters lying between 1.1 mm and 3 mm Experimental determination of the oscillation frequency of all millimetre size drops Comparison of the experimentally obtained dynamic average axis ratios against results of various drop deformation models Evaluation of the dynamic time average form of millimetre size drops after inducing oscillations through collisions
Axis ratios of large drops Chuang and Beard, 1990: J.Atmos.Sci. 47, 1374
Axis ratio temporal variation
Oscillation modes Brook and Latham, 1968: J.Geophys.Res. 73, 7137 Feng and Beard, 1991: J. Atmos. Sci. 48, 1856
Axis ratio histogram 4.24 mm drop Harmonic oscillator
Axis ratios of small drops Chuang and Beard, 1990: J.Atmos.Sci. 47, 1374
Rotating drop video
Axis ratios of small drops Chuang and Beard, 1990: J.Atmos.Sci. 47, 1374
Axis ratios of small drops Chuang and Beard, 1990: J.Atmos.Sci. 47, 1374
Oscillation amplitude of the axis ratio
Axis ratio with amplitude
Data evaluation interpretation of the data rotating drops image processing development Measurements more data on smaller drops (1 mm < D 0 < 3 mm) drop generator Next steps…
Laboruntersuchungen am Mainzer Windkanal Teilprojekt F bisher: Achsenverhältnisses b/a von oszillierenden Tropfen Oszillationsfrequenz Vergleich dynamisches Mittel b/a aus Messungen mit statischem Mittel b/a aus Modellrechnungen andere Einflüsse auf Tropfenform und Achsenverhältnis Ideen für Neuantrag AQUARadar
Laboruntersuchungen am Mainzer Windkanal Teilprojekt F neu: Tropfen, die oberflächenaktive Substanzen enthalten verminderte Oszillation verändertes b/a Turbulenz Einfluss auf b/a elektrische Ladung b/a wird größer Oszillationen, induziert durch Kollisionen Wünsche? Ideen für Neuantrag AQUARadar