The continual growth of computing and storage capabilities enable 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 from Architecture Description Languages (ADL) are a promising solution to this problem. However, they have only been introduced in flat component models. This paper describes Hlcm, a model supporting both connectors and component hierarchy. This is achieved by describing potential interaction of components using the new concept of open connections. Complex interactions such as data sharing and parallel interactions are successfully supported by Hlcm. An implementation, based on model transformation and on CCM, illustrates its feasibility and benefits.