1. WOBBLING OF A LIQUID COLUMN BETWEEN UNEQUAL DISCS
I. Martínez, J. Meseguer, J.M. Perales
IDR/UPM, Universidad Politécnica de Madrid, Madrid, Spain
COSPAR 2004
Monday, 19th July 2004

2. Spacelab-D2 EXPERIMENT “STACO”

3. Automated image edging

4. Automated image edging

5. Time evolution of selected radii

6. Equilibrium and stability of the column Geometrical parameters
Unit length
Relative difference in radii
Slenderness
Reduced slenderness
Excess liquid volume

7. Equilibrium and stability of the column Kinetic parameters
Unit time
Axial acceleration
Lateral acceleration
Solid-body rotation

8. Equilibrium shapes and their stability criterion
Stability limit

9. Theoretical and experimental shapes

10. Dynamics
Axial dynamics of quasi-cylindrical liquid columns

11. Image analysis

12. Conclusions
Long liquid columns are very sensitive to disturbances, and theories are available to analyse in detail the liquid response
Dynamic effects grow when sensitivity increases
Actual liquid column shapes appear oscillating:
Around an equilibrium shape that is unexpected (a residual load shows up)
With a small but non-decaying amplitude (0.5 mm against 14.5 mm)
With a frequency very close to the natural frequency (a period of 12 s)
Useful experimental time is very scarce
(a couple of minutes in half an hour, here)
Unique experiments may have some boundary conditions unknown
(these experiments have not been reproduced yet)
Automated image analysis has progressed a lot, but small problems remain
(we benefit from overall analysis, but details of the discs are not visible)
Digital imaging nowadays would solve many of the old video problems