Two-dimensional stable-layered laboratory-scale experiments for testing density-coupled flow models

A series of laboratory-scale two-dimensional porous medium tank experiments was conducted to study stable-layered variable density flow problems using well-defined experimental parameters and boundary conditions. The experiments were carried out both in a rectangular flow tank and in a more complex geometrical setup aimed at studying variable density flow in geometries similar to geological formations of aquifers and aquicludes connected via fault zones. An impermeable layer within the porous medium tank forced the solutes to pass through a vertical channel, representing a geological fault zone, to reach the outlet of the tank. Flow through the porous medium occurred through a single inflow opening and an outflow opening on the opposite edge of the domain. An image analysis technique delivered 2%, 10%, 50%, and 80% salt concentration isolines at distinct times. Breakthrough curves of the dyed saltwater with an initial density of 1063 g/L were available at any location within the tank. The experimental data are presented as benchmark problems to evaluate numerical codes. A numerical model based on mixed finite elements for the fluid flow problem and a combination of discontinuous Galerkin finite element and multipoint flux approximation methods for the transport turned out to be adequate for the simulation of the physical experiments. The high data availability makes the proposed benchmark experiments a valuable tool for assessing the performance of density-coupled flow models.