Ripples, icicle

RIPPLE FORMATION MECHANISM ON ICICLES UNDER A THIN SHEAR FLOW... 

The above study is not complete in that the comparision of theoretical and experimental results was made only at a single value of Q/l ( = 53.3 [(ml/hr)/cm]). However, for natural icicles Q I does not necessarily take a definite value since the values of Q, radii R, and / = 2kR vary depending on the surrounding environmental conditions. In the present paper, we present the observation result showing the relation between the wavelength of ripples and the diameter, and the computational result of the wavelength of ripples for various values of Q L More detailed comparison of previous models is also made in particular reference to the difference in boundary conditions. 

Figure 2 (a) Observed wavelength of ripples v.v diameter for natural icicles, (b) Calculated wavelength of ripples Q I [(ml/hr)/cm]. 

The observation of natural icicles showed the weak increase of ripple wavelength with icicle diameter. The wavelength also increased slowly with increasing water supply rate per width, which was calculated from the present theoretical model that takes account of the effect of the restoring forces due to gravity and surface tension on the liquid-air surface in the icicle growth under a thin shear flow. The two models for the destabilization and/or stabilization of the solid-liquid interface under a thin shear flow were compared and discussed in some detail. It was concluded that different boundary conditions in the two models lead to the completely different final results. 

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