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.

Präsentation zum Thema: "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."—  Präsentation transkript:

1 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

2 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

3 Axis ratios of large drops Chuang and Beard, 1990: J.Atmos.Sci. 47, 1374

4 Axis ratio temporal variation

5 Oscillation modes Brook and Latham, 1968: J.Geophys.Res. 73, 7137 Feng and Beard, 1991: J. Atmos. Sci. 48, 1856

6 Axis ratio histogram 4.24 mm drop Harmonic oscillator

7 Axis ratios of small drops Chuang and Beard, 1990: J.Atmos.Sci. 47, 1374

8 Rotating drop video

9 Axis ratios of small drops Chuang and Beard, 1990: J.Atmos.Sci. 47, 1374

10 Axis ratios of small drops Chuang and Beard, 1990: J.Atmos.Sci. 47, 1374

11 Oscillation amplitude of the axis ratio

12 Axis ratio with amplitude

13 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…

14 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

15 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