Electrokinetic coupling in unsteady pressure-driven flow through a porous transducer: Fractal capillary bundle model

•A fractal capillary bundle model is used to predict the frequency-dependent streaming potential coefficient of porous media.•The theoretical model of electrokinetic coupling in the unsteady pressure-driven flow is established to characterize the frequency response of the streaming potential coefficient.•An analytic solution of Poisson-Boltzmann equation is obtained for the capillary bundle of porous media with high zeta potential condition.•The proposed model shows satisfactory agreement with experiments and can optimize the parameter configuration of transducers.