It is explored how physicalist mereotopology and Peircean semiotics can be applied to represent models, simulations, and workflows in multiscale modelling and simulation of physical systems within a top-level ontology. It is argued that to conceptualize modelling and simulation in such a framework, two major types of semiosis need to be formalized and combined with each other: Interpretation, where a sign and a represented object yield an interpretant (another representamen for the same object), and metonymization, where the represented object and a sign are in a three-way relationship with another object to which the signification is transferred. It is outlined how the main elements of the pre-existing simulation workflow descriptions MODA and OSMO, i.e., use cases, models, solvers, and processors, can be aligned with a top-level ontology that implements this ontological paradigm, which is here referred to as mereosemiotic physicalism. Implications are discussed for the development of the European Materials and Modelling Ontology, an implementation of mereosemiotic physicalism.