In wireless sensor networks with mobile sink, mobile sink traverse the sensing area and aggregate the data from nodes near the mobile sink. In this scheme, mobile sink can reduce the total energy consumption by dividing the network to the multiple clusters. Since, energy consumption is proportional to the sum of square of communication distance, dividing the network into smaller clusters can reduce the amount of energy required for transmission. Previous researches concluded that increasing number of the cluster reduces energy required for data transmission. However, these ideas do not take into account the energy consumption due to data request message flooding in dense networks. In this paper, we focus on the data request flooding problem which is the massive energy consumption for data request message in dense network. Moreover, we point out that energy consumption of data transmission and data request message are controlled by the number of clusters in the network.