Résumé : The continual growth of computing and storage capabilities enables scientific numerical applications to integrate more and more phenomena in their computations at the price of increased complexity. Hierarchical component models appear as an interesting approach to handle such complexity. However defining and implementing efficient interactions between hierarchical components is a difficult task, especially in the case of parallel and distributed applications. Connectors originating from Architecture Description Languages (ADL) offer a promising solution to this problem. There are however some cases where a simple combination of hierarchy and connectors in a single component model forces users to choose between an efficient implementation of components and their black box behavior. This paper describes HLCM, a model with connectors and hierarchy that provides /open connections/ as a mechanism to describe component interface that enhances encapsulation and eases component implementation replacement while supporting efficient interactions. Complex interactions such as data sharing and parallel method calls are successfully supported by HLCM. An implementation, based on model transformation and on CCM, illustrates its feasibility and benefits.