Effect of drop size

2 Contact Angle Measurements and Surface Characterization Techniques 

A different observation was reported by Cansoy [24] who showed that the measured contact angles for water on several microtextured superhydrophobic surfaces are insensitive to the drop size ranging from 0.5-19 pL. There may be multiple causes for the observation, such as dispensing procedure, extraction of baseline from the drop profile or drop shape analysis. The discrepancy between the Cansoy observation and early work may be resolved if details of the dispensing procedure is provided and images of the sessile droplets and procedure for the drop shape analysis are reported. 

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Brandon S, Haimovich N, Yeger E, Marmur A. (2003) Partial wetting of chemically patterned surfaces the effect of drop size, f Coll Int Sci 263 237-243. 

The effects of drop size and air temperature are readily apparent from Eq. (12-44). The temperature of the drop is the wet-bulb temperature and can be obtained from a psychrometric chart, as described in the previous section. Sample results are plotted in Fig. 12-17. 

Chakraborty, M., Bhattacharya, C. and Datta, S. (2003). Effect of drop size distribution on mass transfer analysis of the extraction of nickel (If) by emulsion hquid membrane. CoUoids Surf. A, 224, 65-74. 

Figure 30 shows the effect of drop size on the foam lifetime for two oil volume fractions (9.1 and 33 %) in the same system. The foam stability goes through a minimum. The increase of stability with drop size can be explained by the mechanism of oil accumulation. The smaller drops accumulate in the Plateau borders to a lesser extent because of their size and lower buoyancy force thus they have less resistance to movement within the Plateau borders. As a result, they are less likely to get trapped... 

Both approaches are useful. The energy approach relates interfadal tension to thermodynamics and thus allows useful results to be derived (e.g., the Kelvin equation of Example 1.1, which gives the effect of drop size on vapor pressure). The force approach is needed to justify using interfacial tension in boimdary conditions involving forces and stresses at interfaces. Such boundary conditions are employed in solving the governing equations of fluid mechanics when fluid interfaces are present. 

Fig. 2.13 Effect of drop size on the contact angle and sliding angle of hot polyethylene droplets on (a) a hydrophobic sol gel coating and (b) a fluoiinated self-assembled-monolayer on silicon wafer...

Cansoy CE (2014) The effect of drop size on contract angle measurements of superhydrophobic surfaces. RSC Adv 4 1197-1203... 

FIG. 11 Entry barrier, P , for silicone oil as a function of the oil drop radius measured at three different concentrations of SDP3S. As a quantitative measure of the effect of drop size on the entry barrier, we use the ratio p = Pc (2 yarnyP (6 pro). The two vertical lines indicate the drop radii (2 and 6 ynm, respectively), which are used to determine p. 

Polymer melts are shear thinning, and the changing viscosities of polymer melts usually adds complexity in the study of drop deformation and breakup. To simplify the research, we investigated the deformation and breakup of model viscoelastic drops (Boger-fluid) in Newtonian liquids under simple shear flow. A specially designed Couette apparatus that can be used to visualize the drop in two dimensions was used to obtain a 3-D representation of the droplet. Different breakup modes are presented and the effect of drop size on drop breakup mode is discussed. 

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