Dew nucleation and growth

Abstract

Dew is the condensation of water vapor into liquid droplets on a substrate. It is characterized by an initial heterogeneous nucleation on a substrate and a further growth of droplets. The presence of a substrate that geometrically constrains the growth is the origin of the peculiarities and richness of the phenomenon. A key point is the drop interaction through drop fusion or coalescence, which leads to scaling in the growth and gives universality to the process. As a matter of fact, growth dynamics are only dependent on substrate and drop dimensionality. Coalescence events lead to temporal and spatio-temporal fluctuations in the substrate coverage, drop configuration, etc., which give rise to a very peculiar dynamics. When the substrate is a liquid or a liquid crystal, the drop pattern can exhibit special spatial order, such as crystalline, hexatic phases and fractal contours. Condensation on a solid substrate near its melting point can make the drop jump.The applications of monitoring dew formation are manifold. Examples can be found in medicine (sterilization process), agriculture (green houses) and hydrology (production of drinkable water).

Droplet condensation on polymer surfaces: A review

“…They found that the drop radius of the individual isolated droplets grows according a power law with exponent 1/3 except for PP surface similar to previous reports. [48][49][50][51]58 Growth rate of a single droplet surrounded by other droplets was found 14%-40% lower than that of a single isolated droplet because of the barrier effect to lateral vapor diffusion. 63 In a further study, Ucar and Erbil investigated the dropwise condensation rate of water breath figures on polyolefin polymer surfaces whose surface free energies were in a close range of 30-37 mJ/m 2 but having different surface roughness and CAH.…”

“…In many experimental studies, water vapor at a specific humidity was sent onto cool surfaces resulting in rapid condensation. [49][50][51]53,58,61,62,65 On the other hand, condensation of water vapor from ambient air (without sending vapor to cool surfaces) was also studied. 59,63,64 Many studies also investigated the growth dynamics of condensed droplets applying theoretical models and simulation.…”

Condensation heat transfer on superhydrophobic surfaces

“…While this mode which is known as filmwise condensation 14 ( Figure 1a) is quite common, the formation of a liquid film is not desired due to the large resistance to heat transfer. Meanwhile, if a surface is coated with a low-energy non-wetting 'promoter' material (i.e., long chain fatty acid, wax, polymer coating, self-assembled monolayer) [15][16][17][18][19] , or if it naturally adsorbs hydrocarbons and impurities on its surface from the surroundings (as in the case of gold, silver, and chromium) [20][21][22] , the vapor forms discrete liquid droplets ranging in size from microns to millimeters [23][24][25] . This process is known as dropwise condensation 26 ( Figure 1b).…”

Percolation-induced frost formation

“…Assuming for simplicity that the drops lie on a squared lattice, this particular value of surface coverage corresponds to an average distance between the droplet interfaces of ≈ 0.8 R . At this point, we measure an average droplet radius of ≈ 10 µ m. Note that the relation between the contact angle, θ, and surface coverage: θ(deg) ≈ 200(1 − 2 ) indicates that there is no significant change in contact angle with temperature [10,11]. A metastable state of supercooled droplets grown by vapor condensation on the substrate is first reached.…”