This paper presents a model that aims to support knowledge retrieval stored in digital repositories through domain ontologies. In this model the ontology contains concepts and relationships which describe a specific part of the world. The model mechanisms aim to reduce the impact of some of the main obstacles identified in the Information Retrieval process such as user specific characteristics, natural language characteristics or retrieval systems limitations. As a result the user, by providing a query to the system, can retrieve relevant information which better meet his information need. A prototype was developed to demonstrate the feasibility of the model using queries in the computer science domain.