[en] Granular gravity driven ﬂows of glass beads have been observed in a silo with a ﬂat bottom. A dc high electric ﬁeld has been applied perpendicularly to the silo to tune the cohesion. The outlet mass ﬂow has been measured. An image subtraction technique has been applied to visualize the ﬂow geometry and a spatiotemporal analysis of the ﬂow dynamics has been performed. The outlet mass ﬂow is independent of voltage, but a transition from funnel ﬂow to rathole ﬂow is observed. This transition is of probabilistic nature and an intermediate situation exists between the funnel and the rathole situations. At a given voltage, two kinds of ﬂow dynamics can occur: a continuous ﬂow or an intermittent ﬂow. The electric ﬁeld increases the probability to observe an intermittent ﬂow.