Heterogeneous Multi-Rate mass transfer models in OpenFOAM®

We implement the Multi-Rate Mass Transfer (MRMT) model for mobile-immobile transport in porous media within open-source finite volume library \textsc{OpenFOAM}\reg \citep{Foundation2014}. Unlike other codes available literature [Geiger, S., Dentz, M., Neuweiler, I., SPE Reservoir Characterisation and Simulation Conference Exhibition (2011); Silva, O., Carrera, J., Kumar, Alcolea, A., Willmann, Hydrology Earth System Sciences 13, (2009)], we propose an implementation that can be applied to complex three-dimensional geometries highly heterogeneous fields, where parameters of MRMT arbitrarily vary space. Furthermore, being built over widely diffused OpenFOAM\reg library, it easily extended included models, run parallel. briefly describe structure < multiContinuumModels > includes formulation based on works [Haggerty, R., Gorelick, S.M., Water Resources Research 31, (1995)] [F. Municchi M. Icardi Phys. Rev. 2, 013041, (2020)]. The is verified against benchmark solutions tested two- random permeability fields. role various physical numerical parameters, including transfer rates, heterogeneities, number terms expansions investigated. Finally, illustrate significant played by heterogeneity mass when porosity are represented using Gaussian