Kinetically engendered subspinodal length scales in spontaneous dewetting of thin liquid films

Numerical simulations reveal emergence of subspinodal length scales in spontaneous dewetting of nonslipping unstable thin liquid films on homogeneous substrates if the liquid viscosity decreases with decrease in film thickness.

Figure 1

Typical variation of mobility $m$ with film thickness $h$ (a) and location of maximum, $h_m$ with $b$ for different values of $M$ and $\beta$ (b). Dashed line in (a) corresponds to constant viscosity case. Lines 1–3 in (b) correspond to ($M$, $\beta$) values of (${10}^2,6.8$), (${10}^6,6.8$), and (${10}^6,16$), respectively.

Figure 2

Film morphology at rupture (a) and evolution of minimum and maximum thicknesses, $h_{\text{min}}$ and $h_{\text{max}}$, (b) with stage coordinate $t_p$ for a 2-nm film having different viscosity ratios $M$ in a domain of size ${\lambda }_m$. Arrow indicates increasing value of $M$ ($1,{10}^2,{10}^4$, and ${10}^6$). $b=6$ nm and $\beta =6.8$ .

Figure 3

Hole-growth phase for a 2-nm film in a domain of size ${\lambda }_m$ with viscosity ratio $M={10}^2$ (a), $M={10}^6$ (b). Profiles 1–6 represent increasing times. $b=6$ nm and $\beta =6.8$.

Figure 4

A magnified view of world lines of primary holes (solid lines) and satellite holes (dashed lines) during dewetting of a film lying in subspinodal regime in a domain size of $16{\lambda }_m$. Film thickness is 2 nm, $M={10}^6$, $b=6$ nm, and $\beta =6.8$.

Figure 5

3D grayscale pictures of morphological evolutions for a 2-nm film in a unit cell of size ${\lambda }_m$ and viscosity ratio $M={10}^6$ undergoing satellite hole formation. Pictures a, b, c, and d correspond to increasing times. $b=6$ nm and $\beta =6.8$.