Some forms of closed world can be encoded in an OWL ontology by explicitly limiting the universe to the known individuals, e.g. setting owl:Thing equivalent to an enumeration of all the known individuals (using owl:oneOf). The extension of a class can also be closed by setting it equivalent to the enumeration of all members. A similar thing can be done for property assertions.
A common motivation for closed world reasoning has to do with Integrity Constraint validation. Indeed, one might want to use OWL in order to validate RDF, Linked Data, virtual RDF, and so on. Pellet Integrity Constraint Validator treats OWL as a schema or validation language for RDF data via auto-generated SPARQL queries that can be executed on any SPARQL-enabled RDF store. Pellet ICV extends core Pellet by interpreting OWL axioms with integrity constraint semantics. That means you can write ontologies that validate RDF data via auto-generated SPARQL queries.