  We present an approach for modeling nanoscale wetting and dewetting of liquid
surfaces that exploits recently developed, sophisticated techniques for
computing van der Waals (vdW) or (more generally) Casimir forces in arbitrary
geometries. We solve the variational formulation of the Young--Laplace equation
to predict the equilibrium shapes of fluid--vacuum interfaces near solid
gratings and show that the non-additivity of vdW interactions can have a
significant impact on the shape and wetting properties of the liquid surface,
leading to very different surface profiles and wetting transitions compared to
predictions based on commonly employed additive approximations, such as Hamaker
or Derjaguin approximations.
