Direct numerical simulations have been conducted with many cluster models of beads and connecting springs in a turbulent channel Β―ow in order to investigate how the low-speed streaks and the small-scale Β―ow related to the streaks are aected by the cluster models. The cluster model represents highly entangled polymers observed in the quiescent and Β―owing aqueous solution. The cluster models were introduced in the buer region to simulate the experiments of Tiederman et al. (Tiederman, W.G., Luchik, T.S., Bogard, D.G., 1985. Wall-layer structure and drag reduction. J. Fluid Mech. 156, 419Β±437) in which the polymer solution was injected from a slot in the channel wall. An experiment has been carried out for visual observation of highly entangled polymers in a turbulent channel Β―ow of the same Reynolds number in order to determine a parameter of the cluster model. The computational results show that the minor streaks and the small-scale eruptive Β―ows associated with the streamwise vortices are attenuated selectively by the cluster models. The length scale and time scale of these structures are comparable to those of the cluster model. On the other hand, the dynamics of large-scale streaks are found to be basically unchanged. These results are consistent with the measurement of a suppression of low threshold Reynolds-stress producing motion by Harder and Tiederman (Harder, K.