Using Heat as a Tracer to Detect the Development of the Recharge Bulb in Managed Aquifer Recharge Schemes

Managed Aquifer Recharge (MAR), the intentional recharge of aquifers, has surged worldwide in the last 60 years as one of the options to preserve and increase water resources availability. However, estimating the extent of the area impacted by the recharge operations is not an obvious task. In this descriptive study, we monitored the spatiotemporal variation of the groundwater temperature in a phreatic aquifer before and during MAR operations, for 15 days, at the LIFE REWAT pilot infiltration basin using surface water as recharge source. The study was carried out in the winter season, taking advantage of the existing marked difference in temperature between the surface water (cold, between 8 and 13 °C, and in quasi-equilibrium with the air temperature) and the groundwater temperature, ranging between 10 and 18 °C. This difference in heat carried by groundwater was then used as a tracer. Results show that in the experiment the cold infiltrated surface water moved through the aquifer, allowing us to identify the development and extension in two dimensions of the recharge plume resulting from the MAR infiltration basin operations. Forced convection is the dominant heat transport mechanism. Further data, to be gathered at high frequency, and modeling analyses using the heat distribution at different depths are needed to identify the evolution of the recharge bulb in the three-dimensional space.

Соотношения взаимности для открытых нелинейных систем в переменных полях

А proof of reciprocity relations for nonlinear systems in inhomogeneous variable electric and magnetic fields in the presence of unsteady spin currents, thermodynamic flows and mechanical disturbances is obtained by the Kubo method in the approximation of Markov relaxation and locally quasi-equilibrium distribution.

Optimizing the quasi-equilibrium state of hot carriers in all-inorganic lead halide perovskite nanocrystals through Mn doping: fundamental dynamics and device perspectives

Hot carrier (HC) cooling accounts for the significant energy loss in lead halide perovskites (LHPs) solar cells. Here, we study HC relaxation dynamics in Mn-doped LHP CsPbI3 nanocrystals (NCs), combining...

Hot atom chemistry: oxygen at stepped platinum surfaces

It is a paradigm in chemistry that chemical reaction are mainly governed by thermodynamics. Within this assumption, reaction rates can be derived from transition state theory which requires a quasi-equilibrium between reactants and activated transition state complexes that is achieved through friction. However, to reach thermal equilibrium through friction takes some time. Here we show, based on ab initio molecular dynamics simulations of the interaction of molecular oxygen with stepped Pt surfaces, that chemical reactions in heterogeneous catalysis can occur in a non-equilibrium fashion when the excess kinetic energy upon entering the potential well of a reaction intermediate is large enough.

On the Effect of Surface Friction and Upward Radiation of Energy on Equatorial Waves

In theoretical models of tropical dynamics, the effects of both surface friction and upward wave radiation through interaction with the stratosphere are oft-ignored, as they greatly complicate mathematical analysis. In this study, we relax the rigid-lid assumption and impose surface drag, which allows the barotropic mode to be excited in equatorial waves. In particular, a previously developed set of linear, strict quasi-equilibrium tropospheric equations is coupled with a dry, passive stratosphere, and surface drag is added to the troposphere momentum equations. Theoretical and numerical model analysis is performed on the model in the limits of an inviscid surface coupled to a stratosphere, as well as a frictional surface under a rigid-lid. This study confirms and extends previous research that shows the presence of a stratosphere strongly shifts the growth rates of fast propagating equatorial waves to larger scales, reddening the equatorial power spectrum. The growth rates of modes that are slowly propagating and highly interactive with cloud-radiation are shown to be negligibly affected by the presence of a stratosphere. Surface friction in this model framework acts as purely a damping mechanism and couples the baroclinic mode to the barotropic mode, increasing the poleward extent of the equatorial waves. Numerical solutions of the coupled troposphere-stratosphere model with surface friction show that the stratosphere stratification controls the extent of tropospheric trapping of the barotropic mode, and thus the poleward extent of the wave. The superposition of phase-shifted barotropic and first baroclinic modes is also shown to lead to an eastward vertical tilt in the dynamical fields of Kelvin-wave like modes.

The art of modelling climate change in time slice integrations: The ICON-ART experience

<p>Climate change is happening in a transient manner – with continuously increasing greenhouse gases in the atmosphere, humans have started a radiative imbalance that leads to rising near-surface temperatures. However, there are good reasons why it makes sense to look at quasi-equilibrium climate change simulations. In such simulations, we approximate climate change by “fixing” the amount of long-lived greenhouse gases and use recurring boundary conditions that are representative of a particular year - past, present or future. With such a setup any climate model should simulate a stable climate (after a spin-up phase) that reveals internal variability and does not show any trends. It is a necessary condition for the validity of the model - if no transience is provided in the boundary conditions – that the model does not drift. With such a model configuration, it is possible to estimate probability density functions, because each year of a multi-annual integration is an equally valid realisation for the meteorology of the pre-selected year.</p> <p>Using such a time-slice approach, sensitivities to well-specified individual changes can be assessed. Here, we provide a range of examples using the ICON-ART modelling system to investigate (idealised) climate change scenarios with respect to different threshold temperatures, jet variability and the climatic impact of the ozone hole. We illustrate how such integrations allow the unambiguous attribution of certain climate change effects, e.g. the change of jet stream variability under global warming or the contribution of the ozone hole to regional surface warming. However, we caution against a strict causality chain of processes in explaining the response, because given the nature of the quasi-equilibrium modelled, consistency might not always imply causality.</p>

Dripping instability of a two-dimensional liquid film under an inclined plate

It is known that the dripping of a liquid film on the underside of a plate can be suppressed by tilting the plate so as to cause a sufficiently strong flow. This paper uses two-dimensional numerical simulations in a closed-flow framework to study several aspects of this phenomenon. It is shown that, in quasi-equilibrium conditions, the onset of dripping is closely associated with the curvature of the wave crests approaching a well-defined maximum value. When dynamic effects become significant, this connection between curvature and dripping weakens, although the critical curvature remains a useful reference point as it is intimately related to the short length scales promoted by the Rayleigh–Taylor instability. In the absence of flow, when the film is on the underside of a horizontal plate, the concept of a limit curvature is relevant only for small liquid volumes close to a critical value. Otherwise, the drops that form have a smaller curvature and a large volume. The paper also illustrates the peculiarly strong dependence of the dripping transition on the initial conditions of the simulations. This feature prevents the development of phase maps dependent only on the governing parameters (Reynolds number, Bond number, etc.) similar to those available for film flow on the upper side of an inclined plate.

Mathematical modeling of the influence of non-catalytic dissociation / recombination of water molecules in the desalination channel on electric convection

The article formulates a two-dimensional mathematical model of non-stationary transport of 1: 1 electrolyte in a potentiodynamic mode, taking into account electroconvection and non-catalytic dissociation / recombination reaction of water molecules in electromembrane systems, which are considered as the desalting channel of an electrodialysis device. The model is described by a system of coupled Navier-Stokes and Nernst-Planck-Poisson equations taking into account the electric force and physically justified boundary conditions. The article establishes the basic laws of mass transport, taking into account the dissociation / recombination of water molecules. It was shown for the first time that a double electric layer of hydrogen and hydroxyl ions arises in the recombination region. It is shown that between the region of recombination and quasi-equilibrium regions of space charge there are regions of electroneutrality and equilibrium with an almost linear distribution of concentrations. It was found that even under prelimiting, but close enough to the limiting current, modes, non-catalytic dissociation of water molecules in the quasi-equilibrium region of space charge occurs so intensely that the concentration of hydrogen and hydroxyl ions becomes comparable to the concentration of potassium and chlorine ions. At overlimiting current densities, due to the appearance of an extended space charge region and intense dissociation of water molecules in this region, as well as an increase in the electric double layer in the recombination region, the space charge and the dissociation / recombination reaction of water molecules significantly affect each other. In turn, this has a decisive effect on electroconvection and, accordingly, on the transport of salt ions.