A coupled heat- and fluid-flow model to study the initial contact between a melt and a water-cooled substrate (belt) is presented. The key elements of the model are the fluid flow and heat transfer of the molten metal (including phase change), waterside cooling, intervening moving metal substrate, and a gas layer generated by an active interfacial “contact” layer. A unique aspect of this article is the introduction of a subgrid model for the description of the contact-layer heat transfer in the initial melt/substrate contact region. The subgrid model, developed around multiphase conservation equations and an Arrhenius reaction model, is incorporated within the framework of macroscopic equations for heat and fluid flow applied to a computational grid much larger than the scale of the contact layer. The model results are compared against experimental casting data, and the predictions are assessed with a view to understanding surface cooling conditions and the impact on surface metallurgy in strip casting of thin-gage product.