Experimental Analysis of Mass Exchange Across a Heterogeneity Interface: Role of Counter‐Current Transport and Non‐Linear Diffusion

Solute transport in heterogeneous and fractured systems is a complex process given the permeability contrasts time scales discrepancies of high-permeability versus low-permeability regions. We studied this phenomenon by injecting solute (dyed water) micromodel comprising single channel contact with porous medium evaluated mass exchange across interface between (resembling free flow media regions). Two sets experiments were performed at three injection rates 0.01, 0.1, 1 ml/hr. Injection dyed water into clean-water-filled (referred to as loading hereafter) clean dyed-water-filled unloading hereafter). The dynamics was recorded using time-lapse optical imaging. Our experimental results demonstrated change rate coefficient much smaller transfer during compared process. It proposed that concentration-dependent counter-current advection-diffusion cause slow-down further delay transport. These may provide explanation for observed slow release contamination aquifers.