Fluid-fluid interfacial area plays an important role for mass- and energy-transfer processes across the interface which is relevant in several hydrogeological and engineering applications, e.g. enhanced oil-gas recovery, CO2 storage in geological formations, unconventional geothermal systems, contaminant removal, etc. Kinetic interface sensitive tracers were designed to determine the size of the interface between two fluids by undergoing hydrolysis at the fluid-fluid interface. This study investigates by means of numerical modelling the influence of heterogeneity on the KIS tracer breakthrough curves in six idealized scenarios (S1-S6). It is an extension of the previous work conducted in “one-dimensional” column experiments by Tatomir et al. (2018) [1]. The changes in interfacial area are created by inclusion of heterogeneities at the Darcy-scale. The results show that KIS tracers can be used in two-dimensional experimental setup and can provide information about the size and dynamic evolution of interfacial area. Therefore, this is a first step for the dimensioning of an experimental flume.

Geological storage of carbon dioxide represents a viable solution to reduce the greenhouse gases in the atmosphere. Romania has initiatives to build a large-scale integrated CO2 capture and storage demonstration project and find suitable on-shore and off-shore CO2 storage locations. Numerical simulators are essential tools helping the design process. These simulators are required to be capable to represent the complex thermo-hydro-mechanical-chemical and biological phenomena accompanying the geological CO2 storage such as, multi-phase flow, compositional effects due to dissolution of CO2 into the brine, non-isothermal effects due to cold CO2 injection, geomechanical effects, mineralization at the reservoir-scale. These processes can be simulated accurately and efficiently with DuMux (www.dumux.org), a free- and open-source simulator. This article presents and reviews briefly these mathematical and numerical models.

The paper presents an EPANET model of a groundwater well field. The method used in the simulations to model the variation of the hydrodynamic levels in wells as a function of the pumped flow rate is discussed, and a comparison to previous simulations that used fixed hydrodynamic levels in the wells is performed. The case study points to a groundwater well field in Romania. The results show that the new method although requiring a more complex EPANET model, provides a solution that is closer to the actual variation of water levels in wells.

The study of the combination of chemical kinetics with transport phenomena is the main step for reactor design. It is possible to deviate from the model behaviour, the cause of which may be fluid channelling, fluid recirculation, or creation of stagnant regions in the vessel, by using a dispersion model. In this paper, the known general solution of the dispersion model for closed vessels is given in a new, straightforward form. In order to improve the classical theoretical solution, a hybrid of analytical and numerical methods is used. It is based on the general analytic solution and the least-squares method by fitting the results of a tracer test carried out on the vessel with the values of the analytic solution. Thus, the accuracy of the estimation for the vessel dispersion number is increased. The presented method can be used to similar problems modelled by a partial differential equation and some boundary conditions which are not sufficient to ensure the uniqueness of the solution.