Upward Water Flow Research Articles

On Preferred Saturation Methods for Geotechnical Flow Tests

Abstract Laboratory flow tests performed on granular materials in rigid-wall permeameters are used to determine the hydraulic conductivity of saturated materials or to study particle migration. For such tests, specimen preparation is important, particularly the saturation process. The presence of gas bubbles in the tested specimen leads to smaller hydraulic conductivity values and may affect particle migration. Therefore, measures must be taken to obtain fully saturated specimens. In order to improve saturation, two elements have to be taken into consideration: first, the presence of gas in the permeant water; second, the presence of gas in the pores of the specimen. Several flow tests are described in ASTM standards. These standards involve different conditioning methods for permeant water (e.g., heating, seepage through a sand filter, cavitation under vacuum), and different specimen saturation methods (e.g., saturation with an upward flow under vacuum, following carbon dioxide flushing). In this article, water deaeration and specimen saturation methods were evaluated and compared using a mass-volume method. In the first phase, the importance of using deaerated permeant water was examined by comparing different conditioning methods for permeant water. Saturation using water in equilibrium with atmospheric pressure was compared with saturation with water heated at 40°C, water deaerated using a sand filter, and water deaerated by cavitation under vacuum. In the second phase, the influence of purging the gas contained in the soil specimen before saturation using carbon dioxide or a vacuum was compared. In both cases, the permeant water was deaerated by cavitation under vacuum. These tests showed that combining a purge of the specimen with carbon dioxide with saturation using an upward flow of water deaerated by cavitation under vacuum yielded the highest degree of saturation for granular specimens in a rigid-wall permeameter. Another advantage of this combination is that it accelerates specimen saturation.

Centrifuge modelling of gas pipelines undergoing freeze–thaw cycles

Frost heave and thaw settlement are two critical factors that need to be considered in the design of chilled gas pipelines in cold regions. Due to the variation in seasonal temperature and operating conditions (e.g., pressure and temperature at the compressor stations), the pipeline temperature in some segments might vary from subzero to above zero during winter and summer, respectively. This study examines the freezing and thawing for cyclic and constant temperatures at the pipeline and ground surfaces based on the response of 14 model pipes tested in a geotechnical centrifuge. The cyclic (temperature) operation reduces the frost heave rate per year and causes net settlement in some cases. When the thaw bulb resulting from an above-zero operating temperature is less than the previously developed frost bulb, upward water flow occurs through the thawed soil, which could alter the pipeline–soil interaction behaviour. Five types of freeze-thaw-induced vertical displacement of the pipe have been identified from the centrifuge test results.

Simulation of water storage in a reclamation cover incorporating tailings consolidation

Successful reclamation of mine tailings requires effective management of the contaminated water generated by the consolidation of tailings over time. Due to uncertainty in predicting consolidation-induced water release, mine planners often use simulation models to prepare for a range of anticipated scenarios. This paper describes the development of the Tailings Management Simulation Consolidation model (TMSim-Consol) using the GoldSim software. TMSim-Consol simulates tailings settlement over time and the upward flow of pore water due to consolidation. The advantages of using system dynamics simulation tools are illustrated by the inherent transparency of the numerical method to end users. A hypothetical reclamation set-up consisting of an oil sands thickened tailings (OSTT) deposit capped by a sand layer was simulated under a range of initial tailings properties. The simulation results showed that soil water storage in the sand cap was highly sensitive to the initial solids contents of the underlying OSTT. To limit the release of contaminated water at the surface, the initial solids content of OSTT needs to be at least 65% before sand capping.

Estimation of places of production of porcelains of unknown origins excavated at the Mietsu Naval Facility site based on differences in the solubility of trace metals during the elutriation process

More than 300 porcelains of unknown origins were excavated at the Mietsu Naval Facility site in Japan in 2009, which was designated by UNESCO as a World Heritage Site in 2015. Forty-nine representative porcelain pieces were chosen and the metals in the porcelains were identified to clarify their places of production by using the synchrotron-based X-ray fluorescence method. The metal composition of porcelains was analysed by a new method designed by the authors based on the difference in the solubility of metal ions during the elutriation process carried out during the manufacturing of porcelain. Niobium (Nb) and zirconium (Zr), which are barely soluble in water, become a part of the clay, whereas rubidium (Rb), which is highly soluble in water, easily gets discharged with the upward flow of water during elutriation. The plotting of integrated fluorescence intensity ratio of Zr/Nb vs. Rb/Nb led to the porcelains being distinguished into three groups based on their places of production: Hasami, Shida, and Arita in Hizen. X-ray diffraction (XRD) patterns of the porcelains and the XRD patterns of the powdered raw pottery stones were determined. Differences in the XRD patterns are also discussed in terms of identifying the production areas of the excavated porcelains.

A Comparative Study of Closure Relations for CFD Modelling of Bubbly Flow in a Vertical Pipe

Commercial code CFX was used to examine the performance of a two-fluid model to predict the details of upward isothermal bubbly flow of air and water in a vertical pipe. The model equations are volume-averaged Navier-Stokes equations that require closure models for interfacial forces and bubble-induced turbulence effects. Two-equation SST and k-epsilon RANS turbulence models were also used. A parametric study of closure models included both standard options in CFX and previously published novel closure models that were implemented with user-defined functions. The CFD simulations were compared with two cases from the MTLoop experiments by Lucas et al. at the Helmholtz-Zentrum Dresden Rossendorf: one with wall-peak void fraction profile (MT039), and another with a core-peak void fraction profile (MT118). The effect of changing the drag force closures was not significant for the set examined. Poor predictions were found when the lift force and wall lubrication models were incompatible in magnitude. There was no significant effect of changing the liquid phase turbulence model. Changing the bubble-induced turbulence models, however, had a significant impact on the radial void fraction profile. The novel wall force from Lubchenko et al. at the Massachusetts Institute of Technology significantly improved the prediction of the near wall void fraction in the wall peak profile.

Experimental investigations of upward-inclined stratified oil-water flows using simultaneous two-line planar laser-induced fluorescence and particle velocimetry

Experiments are performed in low-inclination (≤ 5°) upward stratified oil (Exxsol D140) and water flows. The flows are investigated using a novel two-line laser-based diagnostic measurement technique that combines planar laser-induced fluorescence and particle image/tracking velocimetry to obtain two-dimensional (2-D) space- and time-resolved phase and velocity information. The technique enables direct measurements in the non-refractive-index-matched fluids of interest, as opposed to substitute fluids which are matched optically but whose properties may be less representative of those in real field applications. Flow conditions span in situ Reynolds numbers in the range 1300-3630 in the oil phase and 1810-11540 in the water phase, and water cuts of 10% and 20%. Instantaneous velocity vector-fields reveal the presence of complex flow structures in the water phase at low mixture velocities, which become less coherent with increasing pipe inclinations. These structures contribute to the generation of interfacial waves, increase the unsteadiness of the flow and the rate of momentum transfer to the oil phase. Statistical information on the interface heights, mean axial and wall-normal velocity profiles and fluctuations, Reynolds stresses, and mixing lengths is obtained from the analysis of the spatiotemporally resolved phase and velocity data. The normalised mean and rms velocity characteristics (velocity fluctuations and Reynolds stress) are shown to be weakly-dependent on the pipe inclination as the mixture velocity increases. Finally, predictions from a linear mixing-length model agree reasonably well with measurements for the water layer and near-interface regions.

Evaluation of correlations for prediction of onset of heat transfer deterioration for vertically upward flow of supercritical water in pipe

Supercritical water has great potential as a coolant for nuclear reactor. Its use will lead to higher thermal efficiency of Rankine cycle. However, in certain conditions heat transfer may get deteriorated which may lead to undesirable high clad surface temperature. It is necessary to estimate the operating conditions in which heat transfer deterioration (HTD) will take place, so as to establish thermal margins for safe reactor operation. In the present work, the heat flux corresponding to onset of HTD for vertically upward flow of supercritical water in a pipe is obtained over a wide range of system parameters, namely pressure, mass flux, and pipe diameter. This is done by performing large number of simulations using an in-house CFD code, which is especially developed and validated for this purpose. The identification of HTD is based on observance of one or more peak/s in the computed wall temperature profile. The existing correlations for predicting the onset of HTD are compared against the results obtained by present simulations as well as available sets of experimental data. It is found that the prediction accuracy of the correlation proposed by Dongliang et al. is best among the existing correlations.

Assessment of drainage and filtration of sub-ballast course considering effect of aggregate gradation and subgrade condition

Abstract Ballast contamination due to intrusion of fine particles from subgrade is characterized as a conventional source of ballast fouling. To diminish this phenomenon, sub-ballast layer is incorporated between the subgrade soil and the ballast course of railway track structure. Present study investigates the influence of subgrade type, compaction level and gradation of sub-ballast material and particle size distribution of ballast aggregate on filtration accomplishment of sub-ballast functioned as a filter layer. For this purpose, prepared structure representing placement of sub-ballast and ballast course over subgrade soil is subjected to upward water flow by exerting considerable values of hydraulic head. Both the thickness of ballast contaminated and the percentage of fine particles infiltrated among ballast aggregate are measured. Also, the hydraulic conductivity of sub-ballast aggregate is separately measured. As expected, using granular sub-ballast comprised of broader size range along with further compaction of this filter course leads to the improvement of filtration against intrusion of fine particles from underlying layer into the upper structure. Likewise, observing insufficiency in drainage of prepared sub-ballast under this extreme condition is inevitable. Furthermore, the level of ballast contamination (especially the value of fouling ratio) is higher in the case of providing ballast aggregate with more uniform particle size distribution. Finally, the fouling indices measured evidently reveal that the ballast layer is further contaminated in the case of placement over subgrade type of silt (in comparison with clay).

Natural Circulation of a Fluid in a Thermosiphon Slightly Inclined to the Horizontal

A pronounced stratification of the temperature (density) of the fluid over the cross section of the heating zone occurs in a thermosyphon that is slightly inclined to the horizontal and has a high degree of water filling, which leads to the onset of natural circulation of the medium along the length of the thermosiphon. In this case, there is an upward flow of water or a steam–water mixture in the upper part of the thermosiphon and a downward flow in the lower part. In experiments with a full-scale thermosiphon, the natural circulation in question increased the axial heat transfer through nonboiling water along all thermosiphon zones by three to seven times as compared to the heat transfer in a vertical thermosiphon. The estimated mass flow rate of natural circulation along the heating zone ranged from 25 to 105 kg/(m2 s). The heat-transfer coefficient and friction factor are estimated at the boundary of countercurrent water flows induced by natural circulation. The conditions of poorer cooling of the thermosiphon heating zone due to steam separation at its upper generatrix are examined. A decrease in the mass filling of the thermosiphon, i.e., an increase in the average void fraction of the medium in it, successively leads to the onset of bubbling steam condensation within the transport section and then in the cooling zone, with a decrease in the length of the upper section of nonboiling water. A transition to film condensation of steam occurs at the limit along the entire length of the cooling zone with a countercurrent steam flow and a near-wall film of its condensate above the level of the steam–water mixture in the thermosiphon.

Exploring the impact of long-term evaporation on the relationship between capillary pressure and water saturation in unsaturated porous media

The focus of this work was on understanding the impact of evaporation on the capillary pressure-saturation (Pc-S) state of a porous medium. Evaporation is ubiquitous near the ground surface in the vadose zone, but little is known about how evaporation impacts the relationship between capillary pressure and saturation. The hypothesis driving the work was that the Pc-S relationship is the result of an equilibrium between evaporative water loss, capillary forces, and the upward flow of water to replenish evaporated water. Experiments were conducted using two different porous media, a coarse sand and a nylon membrane with a 20 μm pore size. Long-term evaporation experiments were conducted using different configurations to control evaporation within the media. Results found that increased accessibility to evaporation caused saturation in drainage Pc-S curves to decrease over time, causing the curves to become closer to imbibition Pc-S curves. In the membrane, the high external surface area to pore volume ratio caused changes in evaporative flux to produce rapid changes in the Pc-S state of the medium. One implication of the work is that results suggest that long-term drainage experiments in vented columns may not necessarily provide a meaningful measurement of static Pc-S curve, but rather may be impacted by evaporation.

Assessment of background levels and pollution sources for arsenic and fluoride in the phreatic and confined groundwater of Xi'an city, Shaanxi, China.

The presence of arsenic and fluoride in groundwater and their impacts on human health have been reported in many countries worldwide, but little information is available on As or F- contamination in Xi'an city. This study highlights the distribution and sources of As and F- anomalies in different aquifers of Xi'an city, based on the assessment of natural background levels (NBLs) and threshold values (TVs). Groundwater samples collected from phreatic and confined aquifers were analyzed to evaluate NBLs and TVs, usingmedian + 2MAD, Tukey inner fence (TIF), and percentile-based methods. Results showed that NBLs and TVs of As and F- in the phreatic aquifer were lower than those in the confined aquifer, indicating importance of the geological effects on the enrichment of arsenic and fluoride in the confined aquifer. Combined with hydrogeochemical methods, the distributions of As and F- anomalies show that high concentrations of As in both aquifers and F- in the confined aquifer can be attributed to the upward flow of geothermal water through faults and ground fissures, while high concentrations of F- in the phreatic aquifer may be greatly influenced by contaminated rivers. Although geological structures such as faults and ground fissures contribute to the high concentrations of potentially toxic elements, anthropogenic activities cannot be ignored because over exploitation of groundwater accelerates the development of ground fissures and results in the upward flow and mixing of geothermal water with groundwater in the upper aquifers.

Enhancing harsh environment oil spill recovery using air floatation system

Recovering heavy oil spilled in a harsh environment is challenging especially when dealing with cold marine environments, where sea ice or high sea states are present. The current technology is based on removing oil from the water surface, meanwhile a significant amount of oil particles could remain in the water column due to turbulent ocean conditions and the density of heavy oil. Therefore, in order to enhance the mechanical recovery of heavy oil, capturing oil particles dispersed in the water column is very important. It has been observed that air bubbles can create an upward water flow and thus enhance the flotation of suspended oil particles. The oil floating at surface can then be removed using conventional skimmers. The present paper focuses on developing a lab-scale test program and Computational Fluid Dynamics (CFD) simulation for an enhanced oil spill recovery system and presents the preliminary test results performed at C-CORE. Both stationery and advancing modes of the oil spill recovery system with attached air diffusers were tested. Preliminary test results indicate that the heavy oil recovery ratio can be significantly improved by using air bubbles for oil flotation.

Experimental investigations of kerosene-water two-phase flow in vertical pipe

Oil and water two-phase flow studies are important to the oil industries. This paper aims to determine the flow patterns, holdup, pressure losses, phase inversion, drift flux parameters and mixture properties in vertical upward kerosene and water flow. The experiment was conducted in a 26 mm i.d duct with phase velocities spanning from 0.1 to 1.0 m/s. The averaged holdup was measured using quick close valves in a 1.16 m long test section. The same test section was used to measure the pressure drop. A local impedance probe and high-speed films were used to determine the flow patterns. Six different flow patterns was identified: dispersed bubbly (DB), core annular (CA), bubbly (B), churn turbulent (CT), and elongated water drop (EWD). The kerosene holdup was highest for EWD, spanning from 0.8 to 0.9, followed by CT and CA, which spans from 0.35 to 0.75. The kerosene holdup for bubbly spans from 0.12 to 0.6, being the highest range for all patterns. The phase inversion occurs when the kerosene input fraction is βK = 0.35. There is no evidence of slippage between the dispersed and continuous phases. The drift velocity is due to the misalignment of the dispersed fraction and the mixture velocity profile and the distribution parameter is C0 = 1.10. The pressure loss showed a good agreement with Blasius correlation. The exception is for the bubbly and churn turbulent. The density was determined using the homogeneous model and five different mixture viscosity models were investigated. The pressure loss deviation using (Mukhaimer et al., 2015) mixture viscosity spans from 5 to 25%. The drift-flux correlation increase the predictive capability of the oil fractions in oil pipelines, which contribute to the operational security. In addition, a better pressure drop losses estimative provide in this study helps to a better oil pipeline design.

Reconnaissance report on geotechnical effects and structural damage caused by the 3 January 2017 Tripura earthquake, India

An earthquake of moment magnitude Mw 5.7 shook the northeastern region of India on 3 January 2017 at 14 h:39 min:0.5 s local time. The duration of the tremor lasted for about 5–6 s and had its epicenter in Dhalai District, Tripura, India. Even though the earthquake was of moderate magnitude, it caused damage to several masonry dwellings in Tripura and triggered soil liquefaction, lateral spreading, and landslides near the epicentral area. The sand boils containing appreciable amount of silts were ejected to the ground surface at the Kanchanbari and Kumarghat area due to the liquefaction-induced upward ground water flow. This is possibly the first liquefaction evidence in India induced due to a moderate earthquake magnitude of Mw 5.7. This paper reports the field reconnaissance observations of geotechnical effects and damage to buildings following a shallow, strike-slip earthquake in northeast India on 3 January 2017. In addition, the distribution of surface peak ground acceleration of the earthquake estimated from the empirical equations based on the available data is evaluated and discussed.

High-resolution computed tomography reveals dynamics of desiccation and rehydration in fern petioles of a desiccation-tolerant fern.

Desiccation-tolerant (DT) plants can dry past -100MPa and subsequently recover function upon rehydration. Vascular DT plants face the unique challenges of desiccating and rehydrating complex tissues without causing structural damage. However, these dynamics have not been studied in intact DT plants. We used high resolution micro-computed tomography (microCT), light microscopy, and fluorescence microscopy to characterize the dynamics of tissue desiccation and rehydration in petioles (stipes) of intact DT ferns. During desiccation, xylem conduits in stipes embolized before cellular dehydration of living tissues within the vascular cylinder. During resurrection, the chlorenchyma and phloem within the stipe vascular cylinder rehydrated before xylem refilling. We identified unique stipe traits that may facilitate desiccation and resurrection of the vascular system, including xylem conduits containing pectin (which may confer flexibility and wettability); chloroplasts within the vascular cylinder; and an endodermal layer impregnated with hydrophobic substances that impede apoplastic leakage while facilitating the upward flow of water within the vascular cylinder. Resurrection ferns are a novel system for studying extreme dehydration recovery and embolism repair in the petioles of intact plants. The unique anatomical traits identified here may contribute to the spatial and temporal dynamics of water movement observed during desiccation and resurrection.

Numerical study of effects of vortex generators on heat transfer deterioration of supercritical water upward flow

The occurrence of heat transfer deterioration (HTD) in supercritical pressure boilers, where the wall temperature rises abruptly is an undesirable phenomenon that is limiting the design of new promising engineering applications. This may cause operational problems such as tube burnouts which could result in a catastrophic system failure. Understanding ways of eliminating HTD is of great importance for the design of safe and reliable supercritical pressure boilers. In this paper, vortex generators (VGs) are installed in circular and annular channels to investigate HTD phenomenon of supercritical water flowing upward at high heat flux and low mass flux using shear stress transport (SST) k-ω turbulence model in ANSYS-FLUENT. Results on wall temperature distribution for the smooth and enhanced channels are compared with available experimental data, and good agreements are obtained. The effects of VG’s size, position, and number on HTD are investigated. The results indicate that VG’s size slightly suppresses and delays HTD downstream of the VG, and there exists an optimum size beyond which HTD starts to aggravate. A strong effect of VGs on heat transfer coefficient (HTC) profiles is observed at locations where VGs are installed and at the downstream locations, with the normalized HTC showing that the wall temperature oscillates a couple of times before becoming stable once the flow returns to fully developed state. The VG’s position has the most significant effect on HTD for any single VG. Increasing the number of VGs installed in-line at the start of the major peak baselines significantly suppresses and delays the peak. Mechanism analysis based on radial distributions of velocity and turbulent kinetic energy (TKE) at different axial positions of both channels shows that HTD suppression is caused by the weakening of the buoyancy effect due to increased TKE near the wall downstream of the VG, whereas the delay is caused by the boundary layer recovery effect due to flow redevelopment after being disrupted by the VG.

Determining thermal diffusivity using near‐surface periodic temperature variations and its implications for tracing groundwater movement at the eastern margin of the Tibetan Plateau

AbstractThe thermal diffusivity is the key parameter that controls near‐surface temperature where periodic temperature variation is progressively attenuated and delayed with depth. This article presents the results of apparent thermal diffusivity using temperatures recorded by a bedrock temperature measurement network in the fault zones of western Sichuan. High sensitivity temperature sensors (10−4 K) were installed at a maximum depth reaching 30 m. The apparent thermal diffusivities were deduced from both amplitude damping and phase shifting of annual temperature variations between two different depths. Under pure conduction, the thermal diffusivity determined through the phase method (αΦ) should be equivalent to that determined through the amplitude method (αA), whereas effects of the upward (downward) water flow are evidently reflected in the amplitude decay to make αΦ larger (lesser) than αA. The discrepancy between αΦ and αA can thus be a tracer of water movement or convective heat transfer. The calculated αΦ of the measurement stations varies from 1.22 × 10−6 to 3.00 × 10−6 m2/s, and the estimated αA ranges from 0.93 × 10−6 to 2.41 × 10−6 m2/s. Two regimes of heat transfer underground were suggested from the results. Conductive heat transport prevails over the nonconductive processes at five stations, which is characterized by αΦ coincident with αA for the same depth pair. On the contrary, the values of αΦ differ from αA at six stations in the intersection area of the Y‐shaped fault system, implying that convective heat transfer also plays a comparably important role. This finding is consistent with the hot springs distribution of the area. The results also indicate that water moves upward with an average Darcy velocity of approximately −1 × 10−7 m/s in this region. Our research provides new evidence for the hydrothermal activity in the fault zones at the eastern margin of the Tibetan Plateau.

A model of heat transfer coefficient for supercritical water considering the effect of heat transfer deterioration

Supercritical water has been widely used as working fluid in many thermodynamic cycles, predicting heat transfer coefficients of supercritical water precisely is of great importance to the system design. However, most of the existed correlations could not give satisfying results when heat transfer deterioration happens. In view of this, based on the mechanism of heat transfer deterioration, a physical model considering the effect of buoyancy and flow acceleration under heat transfer deterioration in the vertically upward flow of the supercritical water is presented in this paper. The modification of the shear stress under the combined effect of buoyancy and flow acceleration is theoretically analyzed, and the relationship between the shear stress modification and heat transfer deterioration is obtained. Based on this model, a heat transfer correlation is derived using a semi-theoretical, semi-empirical approach. The performance of the newly-developed correlation is evaluated and compared with the existed ones. The results show that the present correlation gives reasonable prediction accuracy and is capable of predicting the heat transfer behaviors of heat transfer deterioration of supercritical water.

Transient critical heat flux of upward water flow boiling in vertical small tube at slow velocity

Transient critical heat flux of upward water flow boiling in vertical small tube at slow velocity

Heat losses associated with the upward flow of air, water, CO2 in geothermal production wells

This present work reports on the heat losses associated with the upward flow of hot air, water, and CO2 in a production well. The heat losses considered here are the frictional heat loss, the gravitational heat loss, the Joule-Thomson effect, and the conduction heat loss to the surrounding rock formation. These heat losses were characterized using the mass flow rate, the operation time as variable parameters while the surrounding formation was assumed to have constant properties with a linear geothermal gradient. The results show that, the frictional heat loss was small while the influences of the others depended on the flow conditions and the operation time. For water, the Joule-Thomson effect was a heating effect and its magnitude was comparable to that due to the gravitational effect. The conduction heat loss was dominant for all situations. For air as well as CO2, the Joule-Thomson effects were the cooling effects. For low mass flow rates, the conduction heat loss was the dominant heat loss during the initial stages of the operation and the combined heat losses due to the gravitational and the Joule-Thomson effects became dominant during the later times. For high mass flow rates, throughout the operation life time, the gravitational and the Joule-Thomson effects were the dominant heat losses that control the temperature of air and CO2 in the production well.