Wireless sensor networks generally have three kinds of objects: sensor nodes generating data, sinks gathering the data, and users that send queries and receive data via the sinks. In addition, the user and the sinks are mostly connected to each other by infrastructure networks. The users, however, should receive the data from the sinks through multi-hop communications between disseminating sensor nodes if such users move into the sensor networks without infrastructure networks. To support mobile users in wireless sensor network, previous work has studied various user mobility models. Nevertheless, such approaches are not compatible with the existing data-centric routing algorithms, and it is difficult for the mobile users to gather data efficiently from sensor nodes due to their mobility. To improve the shortcomings, we propose a view of mobility for wireless sensor networks and propose a model to support a user mobility that is independent of sinks. The model is flexible regarding the number of sinks. Furthermore, it considers a situation in which there is no sink and user. The proposed model, finally, is evaluated by simulation of delivery ratio, latency, and network lifetime.