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Item type:Publication, Access status: without files , The Role of Wind Velocity in Saline Water Evaporation from Porous Media and Surface Salt Crystallization Dynamics(2025-07-06); ; ; ; This study systematically investigates the effect of wind flow on evaporation dynamics and salt crystallization patterns in porous media. Well-controlled experiments were conducted in a laboratory wind tunnel, where the surface of sand columns saturated with freshwater and NaCl solutions at concentrations of 10%, 15%, and 20% were subjected to wind flows of 0.5 and 5 m/s, corresponding to laminar and turbulent flow regimes, respectively. Mass loss measurements from the samples, combined with optical imaging of their surfaces, revealed distinct evaporation dynamics and crystallization patterns. We observed that the interaction between intermittent turbulent airflow and evolving salt crystals on the surface resulted in a relatively uniform crystallization pattern. In contrast, under laminar airflow conditions, salt crystal nucleation and formation primarily occurred at the leading edge of the sample, particularly at lower salt concentrations. We further investigated the impact of enhanced evaporative mass loss in the presence of wind on crystallization dynamics by quantifying the crystal coverage and its lateral extent on the surface. Under turbulent flow conditions, we observed that full coverage of the surface with salt crystals requires 2 to 3 times higher evaporative losses in 10% NaCl sample relative to the 15% and 20% samples, respectively. These findings highlight the complex interplay between evaporation and crystallization processes under varying airflow conditions, thus offering valuable insight for improving hydrological and climatological modeling.Publicationtype: Journal Article32 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , The role of wind velocity in saline water evaporation from porous media and surface salt crystallization dynamicsSaline water evaporation from porous media with the corresponding surface salt crystallization patterns play a vital role in many environmental and engineering applications. While the impact of factors such as type and concentration of salt, particle size and angularity, and ambient temperature and humidity are relatively well characterized [1]–[3], the influence of wind and aerodynamic conditions on saline water evaporation and salt crystallization is not fully understood. We conducted a series of laboratory experiments in a wind tunnel to systematically investigate the effect of wind flow on saline water evaporation and dynamics of salt crystallization. Cylindrical sand columns (D: 5 cm – H: 20 cm) were placed in the test section of the wind tunnel. Surface of the samples were exposed to uniform mean wind velocities of 0.5 and 5 m/s. To keep samples fully saturated during the evaporation experiments, sand columns were supplied from Mariotte bottles containing 10, 15, and 20% NaCl solutions. Evaporation rates were monitored by measuring mass losses from Mariotte bottles, while salt crystallization patterns were captured using an optical camera positioned above the surface of columns. Preliminary results indicate that variation in aerodynamic conditions and turbulence patterns, driven by changes in wind velocity and surface roughness (due to crystal growth), significantly alter evaporation rates and salt crystallization process. Distinct crystallization patterns were observed with variation of wind velocity with possible influences on the evaporative fluxes. Using the measured data, we will identify the key effects of air flow regimes coupled with the salt concentration on evaporative losses and the evolution of crystallized salts at the surface, which will be important for a wide range of environmental and hydrological applications.Publicationtype: Conference Paper13 18 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Quantifying salt crystallization impact on evaporation dynamics from porous surfaces(2024-11-14); ; ; ; We investigated the effects of salt crystallization on the dynamics of saline water evaporation in porous media. Water mass loss rates from sand columns supplied with NaCl solutions at three concentrations were monitored under controlled ambient conditions. The formation and evolution of salt crystals over sand surfaces were synchronously imaged optically and thermally. Despite identical experimental and ambient conditions, we observed distinct crystallization dynamics that affected evaporative mass loss rates for similar salt concentrations, highlighting high variability of crystallization and its impact on evaporation. We observed the enhancement of maximum evaporation rates by factors of 3 to 14 under our experimental conditions and attributed this enhancement to the formation and evolution of porous crystalized salts at the surface. Additionally, visible intermittent temperature fluctuations of the salt crust were quantified using thermal imagery attributed to the dynamic processes of crystallization, dissolution and evaporation occurring simultaneously at the surface.Publicationtype: Journal Article22 42 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , How does surface salt crystallization influence saline water evaporation from porous media in the presence of a water table?Saline water evaporation from soil is ubiquitous in many environmental and hydrological processes such as soil water evaporation, vegetation and crop production. It plays an important role on soil salinity influencing soil health and ecosystem functioning. When the salt concentration in soil substantially exceeds its solubility limit as a result of water evaporation, salt crystallization occurs (1). Although how different parameters such as type of salt, soil texture, angularity of the grains, presence of a water table and atmospheric condition influence the formation (1-6), patterns and dynamics of crystallization is relatively well understood, how exactly the presence of crystalized salt influence the evaporation dynamics is poorly understood with the majority of the previous investigations offering qualitative description. We thus aimed at quantifying the effect of crystallized salt on dynamics of saline water evaporation from porous media under controlled laboratory conditions. To do so, three sets of experiments were conducted using NaCl solutions of 10%, 15%, and 20% (mass basis) in a climate chamber with constant air temperature and relative humidity of 30 °C and 30%, respectively. Sandy soil with particle sizes ranging from 0.4 to 0.8 mm and density of 2.65 gr/cm3 was used as the model porous medium packed in cylindrical glass columns (20 cm height - 8 cm diameter). The columns were supplied from Marriott’s flasks to keep the columns fully saturated during the evaporation experiments. Mass loss from sand samples was measured digitally while crystallization dynamics and their corresponding thermal signatures were monitored with a high resolution optical camera and a thermal imager, respectively. This setup enables us to quantify the contribution of crystalized salt on evaporation. Our preliminary results highlight the key role of salt crystallization on changing evaporation dynamics from sand columns relative to the reference sample supplied with freshwater. Despite the impact of salinity in reducing saturated vapor pressure, we observed enhanced evaporation rates from samples with crystalized salt at the surface by a factor of 4 to 12 (depending on the salt concentration). Furthermore, highly resolved surface temperature dynamics recorded by the thermal camera enabled us to investigate the correlations between the intermittent temperature fluctuations of salt crystals and the evaporative flux from the surface. Our findings provide new insights regarding how the presence of crystalized salt at the surface influences the soil evaporation dynamics.Publicationtype: Conference Paper109 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Water table depth and soil salinization : from pore-scale processes to field-scale responsesThe accumulation of salts in soils adversely influences plant growth and biological activity resulting in loss of yields and soil ecosystem services. Water table depth plays an important role on solute distribution through the unsaturated zone. We focus on the relationship between saline water evaporation from soil surfaces and water table depths. When the water table was hydraulically connected to the surface, we found more evaporatively driven sodium chloride precipitation at the surface with deeper water tables relative to shallow ones. We attribute this result to lower surface water contents that reach solubility limit sooner and support an expanding salt crust. Thermal imaging confirmed that when surface is hydraulically connected to the water table, capillary flows through the porous precipitated salt maintain the evaporative flux. Macroscopic continuum-scale numerical simulations demonstrate higher solute concentration closer to the surface in the case of deeper water tables supporting the microscopic picture attributed to fewer evaporation and solute deposition sites at the surface with deeper water tables. Insights from the laboratory-scale experiments and numerical studies were used to describe soil salinity at much larger scales. We employed two global-scale databases for topsoil salinity, soil texture, and water table depths to link our laboratory-scale findings with long-term and field-scale observations. The results illustrate the importance of pore-scale physics and processes on constraining the field-scale responses.Publicationtype: Journal Article88 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Water table depth and soil salinity: Pore-scale physics defining large-scale responsesPublicationtype: Conference Presentation27 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Multiscale analysis of the interaction between water table depth and soil salinityPublicationtype: Journal Article16 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Kinetic Approach to Model Reactive Transport and Mixed Salt Precipitation in a Coupled Free-Flow–Porous-Media System(2016-09-01); ; ; ; Evaporative salinization of the agricultural soil is a chronic problem in arid, semiarid and coastal regions worldwide. As a shallow subsurface issue, it is strongly influenced by the free-flow (henceforth, FF) and porous-media (henceforth, PM) flow and transport processes. In specific, it is mainly affected by the mass, momentum and energy exchange between the FF and the PM regions. Furthermore, salt precipitation in such systems is strongly determined by the interaction between different dissolved ionic species. In the scope of this work, we extend the REV-scale coupled FF–PM model concept for salinization proposed by Jambhekar et al. (Transp Porous Media, 2015), to describe reactive transport of ionic species Na +, Cl - and I - and mixed salt precipitation (here, NaCl and NaI). In the first part of our numerical analysis, we illustrate precipitation behavior of NaCl using equilibrium and kinetic approaches. Both approaches are found to be in good agreement with experimental observations. However, in the literature it is often discussed that for mixed salt systems found in the nature, the equilibrium precipitation–dissolution assumption is not easily justifiable. Therefore, in the second part of our numerical analysis, we extend the kinetic approach to describe mixed salt precipitation in an NaCl–NaI system and compare it with the equilibrium precipitation approach. Our numerical analysis indicate that the simulation results for these approaches are very similar and analogous with the phenomenological explanations.Publicationtype: Journal Article45 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Free-Flow–Porous-Media Coupling for Evaporation-Driven Transport and Precipitation of Salt in Soil(2015-11-01); ; ; Evaporative salinization of soil is a common issue observed in arid and coastal regions. This process is driven by mass, momentum and energy exchange between the porous medium and the free-flow region. To analyze such coupled systems, we present a representative elementary volume-scale model concept for coupling non-isothermal multi-phase compositional porous-media flow and single-phase compositional laminar free flow. Our numerical results illustrate evaporation behavior from a porous medium initially saturated with NaCl solution, manifesting its influence on dissolved salt distribution, salt precipitation and porous-media properties. We show that the new model is capable to capture the evaporation physics for different stages of evaporative salinization and compare the numerical results to two different experimental datasets: (1) cumulative mass loss of water and dissolved salt during stage-1 of saline water evaporation and (2) evaporation rate for different stages of evaporative salinization. In addition, influence of the initial salt concentration on the saline water saturation vapor pressure and transition to stage-2 evaporation are analyzed and discussed.Publicationtype: Journal Article29