Temporal scaling of interfaces propagating in porous media

To better understand the temporal behavior of a roughening meniscus driven by capillary forces during the imbibition of a viscous fluid in porous media, we measure the height-height autocorrelation function C(t) using a constant driving force. We find C(t){~}t^β, with {β}=0.56±{}0.03, and provide experimental evidence for driving the force independent temporal scaling behavior of a propagating wetting front in the presence of quenched noise. We interpret the value of {β} in terms of the possibility that the dynamics may be governed by nonvanishing nonlinearity due to anisotropic depinning.