scholarly journals The Significance of Vertical and Lateral Groundwater–Surface Water Exchange Fluxes in Riverbeds and Riverbanks: Comparing 1D Analytical Flux Estimates with 3D Groundwater Modelling

Water ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 306
Author(s):  
Gert Ghysels ◽  
Christian Anibas ◽  
Henock Awol ◽  
Abebe Debele Tolche ◽  
Uwe Schneidewind ◽  
...  
Keyword(s):  
Water Exchange ◽  
Vertical Flux ◽  
Temperature Profiles ◽  
Vertical Flow ◽  
Groundwater Model ◽  
Complex Flow ◽  
Heterogeneous Structures ◽  
Spatially Distributed ◽  
Heat Transport Equation ◽  
Exchange Flux

Riverbed temperature profiles are frequently used to estimate vertical river–aquifer exchange fluxes. Often in this approach, strictly vertical flow is assumed. However, riverbeds are heterogeneous structures often characterised by complex flow fields, possibly violating this assumption. We characterise the meter-scale variability of river–aquifer interaction at two sections of the Aa River, Belgium, and compare vertical flux estimates obtained with a 1D analytical solution to the heat transport equation with fluxes simulated with a 3D groundwater model (MODFLOW) using spatially distributed fields of riverbed hydraulic conductivity. Based on 115 point-in-time riverbed temperature profiles, vertical flux estimates that are obtained with the 1D solution are found to be higher near the banks than in the center of the river. The total exchange flux estimated with the 3D groundwater model is around twice as high as the estimate based on the 1D solution, while vertical flux estimates from both methods are within a 10% margin. This is due to an important contribution of non-vertical flows, especially through the riverbanks. Quasi-vertical flow is only found near the center of the river. This quantitative underestimation should be considered when interpreting exchange fluxes based on 1D solutions. More research is necessary to assess conditions for which using a 1D analytical approach is justified to more accurately characterise river–aquifer exchange fluxes.

scholarly journals Mathematical Modelling for Furnace Design Refining Molten Aluminum

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1798
Author(s):  
Alfredo Alan Flores Saldívar ◽  
Rodrigo Juárez Martínez ◽  
Alfredo Flores Valdés ◽  
Jesús Torres Torres ◽  
Rocío Maricela Ochoa Palacios ◽  
...  
Keyword(s):  
Mathematical Modelling ◽  
Melting Furnace ◽  
Temperature Profiles ◽  
Complex Flow ◽  
Optimal Position ◽  
Combustion Gases ◽  
Physical Experiments ◽  
Simulation Based ◽  
Final Design ◽  
Magnesium Removal

The design of an aluminium melting furnace has faced two challenges: mathematical modelling and simulative optimization. This paper first uses fluid dynamics to model the aluminium process mathematically. Then, the model is utilized to simulate a round shaped reverberatory furnace for melting aluminium alloys. In order to achieve the highest thermal efficiency of the furnace, modelling and simulation are performed to predict complex flow patterns, geometries, temperature profiles of the mixture-gas air through the main chamber, as well as the melting tower attached to the furnace. The results led to the establishment of optimal position and angle of the burner, which are validated through physical experiments, ensuring recirculation of the combustion gases through the melting chamber and the melting tower. Furthermore, a proper arrangement of refractory materials is derived to avoid heat losses through the outer surface of the furnace. Temperature profiles are also determined for the optimization to arrive at the final design of the furnace. Compared with manual designs previously practiced, the simulation-based optimal design of furnaces offers excellent guidance, an increase in the aluminium processing and magnesium removal for more refined alloys, and an increased processing rate of aluminium chip accession.

Influence of Water Exchange in Tide and Wave for Large Harbor with One Entrance

2013 ◽  
Vol 405-408 ◽  
pp. 1411-1414
Author(s):  
Jie He ◽  
Wen Jie Xin
Keyword(s):  
Point Source ◽  
Water Flow ◽  
Tidal Current ◽  
Water Exchange ◽  
Water Environment ◽  
Zhejiang Province ◽  
Polluted Water ◽  
Influence Of Water ◽  
The Waves ◽  
Exchange Flux

For the large coastal harbor with one entrance attacked badly from the waves and sands from the sea, it is advantaged to break waves and produce sands, but not advantaged for the water exchange flux, especially when a point source appearing inside the harbor, the polluted water is difficult to flow into the sea in time and be diluted by the water from outside. The water flow in estuary presents the character of to-and-fro flow, and the polluted source will flow into harbor with the flood tide and pollute the harbor secondly, although it has been outside the harbor at least with the ebb tide. For the harbor with one entrance against waves, the polluted source will be more difficult to be transported to the outside when waves coming, and the water environment capacitance will decline rapidly for the polluted water not to be absorbed. It is Taizhou Wenling harbor for example in Zhejiang province, and the movement of water particle is simulated in tidal current and wave to describe the movement of the point source transported not diffused. The rusults show that the capacity of water exchange for the large harbor wih one entrance will be declined in both tidal current and wave.

Temperature profiles with respect to inhomogeneity and geometry of the human body

1988 ◽  
Vol 65 (3) ◽  
pp. 1110-1118 ◽  
Author(s):  
J. Werner ◽  
M. Buse
Keyword(s):  
Human Body ◽  
Three Dimensional ◽  
The Body ◽  
Physiological Data ◽  
Physical Parameters ◽  
Temperature Profiles ◽  
Metabolic Heat ◽  
Spatially Distributed ◽  
Adequate Representation ◽  
Neutral Conditions

Temperature profiles within the human body are highly dependent on the geometry and inhomogeneity of the body. Physical parameters such as density and heat conductivity of the various tissues and variables such as blood flow and metabolic heat production of different organs are spatially distributed and thereby influence the temperature profiles within the human body. Actual physiological knowledge allows one to take into account up to 54 different spatially distributed values for each parameter. An adequate representation of the anatomy of the body requires a spatial three-dimensional grid of at least 0.5-1.0 cm. This is achieved by photogrammetric treatment of three-dimensional anatomic models of the human body. As a first essential result, the simulation system has produced a realistic picture of the topography of temperatures under neutral conditions. Compatibility of reality and simulation was achieved solely on the basis of physical considerations and physiological data base. Therefore the simulation is suited to the extrapolation of temperature profiles that cannot be obtained experimentally.

scholarly journals The effect of sediment thermal conductivity on vertical groundwater flux estimates

2018 ◽  
Author(s):  
Eva Sebok ◽  
Sascha Müller
Keyword(s):  
Thermal Conductivity ◽  
Homogeneous Distribution ◽  
Temperature Profiles ◽  
High Flux ◽  
Water Interface ◽  
Heterogeneous Distribution ◽  
Groundwater Flux ◽  
Sediment Temperature ◽  
Spatially Distributed ◽  
Lagoon Environment

Abstract. Vertical sediment temperature profiles are frequently used to estimate vertical fluid fluxes. In these applications using heat as a tracer of groundwater flow, the thermal conductivity of saturated sediments (ke) is often given as a standard literature value and assumed to have a homogeneous distribution in the vertical space. In this study vertical sediment temperature profiles were collected both in a high-flux stream and a low-flux lagoon environment in a sand-, and peat-covered area. ke was measured at the location of each temperature profile at several depths below the sediment-water interface up to 0.5 m with a measurement spacing of 0.1 m. In general ke values measured in this study ranged between 0.55 and 2.96 W m−1 °C−1 with an increase with depth from the sediment-water interface. The effect of using a vertically homogeneous or heterogeneous distribution of measured ke values on vertical flux estimates was studied with a steady-state HydroGeoSphere model. In the high-flux stream environment estimated fluxes varied between 0.03 and 0.71 m d−1 and in the low-flux lagoon between 0.02 and 0.23 m d−1. It was found, that using a vertically heterogeneous distribution of sediment thermal conductivity did not considerably change the fit between observed and simulated temperature data compared to a homogeneous distribution of ke. However, depending on the choice of sediment thermal conductivities, flux estimates decreased by up to 64 % or increased by up to 75 % compared to using a standard ke sediment thermal conductivity for sand, frequently assumed by previous local studies. Hence, our study emphasizes the importance of using spatially distributed thermal properties in heat flux applications in order to obtain more precise flux estimates.

scholarly journals On the distortions in calculated GW parameters during slanted atmospheric soundings

2017 ◽  
Author(s):  
Alejandro de la Torre ◽  
Peter Alexander ◽  
Torsten Schmidt ◽  
Pablo Llamedo ◽  
Rodrigo Hierro
Keyword(s):  
Aspect Ratio ◽  
Gravity Waves ◽  
Momentum Flux ◽  
Elevation Angle ◽  
Vertical Flux ◽  
Temperature Profiles ◽  
Model Simulations ◽  
Horizontal Momentum ◽  
Two Parameters ◽  
Atmospheric Gravity

Abstract. The significant distortions introduced in the measured atmospheric gravity wavelengths by soundings other than in vertical and horizontal directions, are discussed as a function of elevation angle of the sounding path and the gravity waves aspect ratio. Under- or overestimation of real vertical wavelengths during the measurement process depends basically on the value of these two parameters. The consequences of these distortions on the calculation of the energy and vertical flux of horizontal momentum are analyzed and discussed in the context of two experimental limb satellite setups: GPS-LEO radio occultations and TIMED/SABER measurements. Possible discrepancies previously found between the momentum flux calculated from satellite temperature profiles, on site and from model simulations, may, to a certain degree, be attributed to these distortions. A recalculation of previous momentum flux climatologies based on these considerations seems to be a difficult goal.

scholarly journals Spatially distributed sensitivity of simulated global groundwater heads and flows to hydraulic conductivity, groundwater recharge and surface water body parameterization

2019 ◽  
Author(s):  
Robert Reinecke ◽  
Laura Foglia ◽  
Steffen Mehl ◽  
Jonathan D. Herman ◽  
Alexander Wachholz ◽  
...  
Keyword(s):  
Surface Water ◽  
Hydraulic Conductivity ◽  
Groundwater Recharge ◽  
Water Body ◽  
Distributed Parameter ◽  
Groundwater Model ◽  
Surface Water Body ◽  
Spatially Distributed ◽  
Gradient Based ◽  
The Impact

Abstract. In global hydrological models, groundwater storages and flows are generally simulated by linear reservoir models. Recently, the first global gradient-based groundwater models were developed in order to improve the representation of groundwater-surface water interactions, capillary rise, lateral flows and human water use impacts. However, the reliability of model outputs is limited by a lack of data as well as model assumptions required due to the necessarily coarse spatial resolution. The impact of data quality is presented by showing the sensitivity of a groundwater model to changes in the only available global hydraulic conductivity data-set. To better understand the sensitivity of model output to uncertain spatially distributed parameter inputs, we present the first application of a global sensitivity method for a global-scale groundwater model using nearly 2000 steady-state model runs of the global gradient-based groundwater model G3M. By applying the Morris method in a novel domain decomposition approach that identifies global hydrological response units, spatially distributed parameter sensitivities are determined for a computationally expensive model. Results indicate that globally simulated hydraulic heads are equally sensitive to hydraulic conductivity, groundwater recharge and surface water body elevation, though parameter sensitivities vary regionally. For large areas of the globe, rivers are simulated to be either losing or gaining, depending on the parameter combination, indicating a high uncertainty of simulating the direction of flow between the two compartments. Mountainous and dry regions show a high variance in simulated head due to numerical difficulties of the model, limiting the reliability of computed sensitivities in these regions. This instability is likely caused by the uncertainty in surface water body elevation. We conclude that maps of spatially distributed sensitivities can help to understand complex behaviour of models that incorporate data with varying spatial uncertainties. The findings support the selection of possible calibration parameters and help to anticipate challenges for a transient coupling of the model.

scholarly journals Estimation of Uncertainty in Air–Water Exchange Flux and Gross Volatilization Loss of PCBs: A Case Study Based on Passive Sampling in the Lower Great Lakes

2016 ◽  
Vol 50 (20) ◽  
pp. 10894-10902 ◽  
Author(s):  
Ying Liu ◽  
Siyao Wang ◽  
Carrie A. McDonough ◽  
Mohammed Khairy ◽  
Derek Muir ◽  
...  
Keyword(s):  
Great Lakes ◽  
Passive Sampling ◽  
Water Exchange ◽  
Exchange Flux ◽  
Estimation Of Uncertainty

scholarly journals Spatially distributed sensitivity of simulated global groundwater heads and flows to hydraulic conductivity, groundwater recharge, and surface water body parameterization

2019 ◽  
Vol 23 (11) ◽  
pp. 4561-4582 ◽  
Author(s):  
Robert Reinecke ◽  
Laura Foglia ◽  
Steffen Mehl ◽  
Jonathan D. Herman ◽  
Alexander Wachholz ◽  
...  
Keyword(s):  
Surface Water ◽  
Hydraulic Conductivity ◽  
Groundwater Recharge ◽  
Water Body ◽  
Groundwater Model ◽  
Decomposition Approach ◽  
Surface Water Body ◽  
Spatially Distributed ◽  
Gradient Based ◽  
The Impact

Abstract. In global hydrological models, groundwater storages and flows are generally simulated by linear reservoir models. Recently, the first global gradient-based groundwater models were developed in order to improve the representation of groundwater–surface-water interactions, capillary rise, lateral flows, and human water use impacts. However, the reliability of model outputs is limited by a lack of data and by uncertain model assumptions that are necessary due to the coarse spatial resolution. The impact of data quality is presented in this study by showing the sensitivity of a groundwater model to changes in the only available global hydraulic conductivity dataset. To better understand the sensitivity of model output to uncertain spatially distributed parameters, we present the first application of a global sensitivity method for a global-scale groundwater model using nearly 2000 steady-state model runs of the global gradient-based groundwater model G3M. By applying the Morris method in a novel domain decomposition approach that identifies global hydrological response units, spatially distributed parameter sensitivities are determined for a computationally expensive model. Results indicate that globally simulated hydraulic heads are equally sensitive to hydraulic conductivity, groundwater recharge, and surface water body elevation, though parameter sensitivities vary regionally. For large areas of the globe, rivers are simulated to be either losing or gaining, depending on the parameter combination, indicating a high uncertainty in simulating the direction of flow between the two compartments. Mountainous and dry regions show a high variance in simulated head due to numerical instabilities of the model, limiting the reliability of computed sensitivities in these regions. This is likely caused by the uncertainty in surface water body elevation. We conclude that maps of spatially distributed sensitivities can help to understand the complex behavior of models that incorporate data with varying spatial uncertainties. The findings support the selection of possible calibration parameters and help to anticipate challenges for a transient coupling of the model.

Water Currents and Exchange between Severn Sound and Georgian Bay, Lake Huron, during 1988

1995 ◽  
Vol 30 (4) ◽  
pp. 607-618
Author(s):  
Balbir Kohli
Keyword(s):  
Residence Time ◽  
Mean Residence Time ◽  
Water Exchange ◽  
Lake Huron ◽  
Maximum Speed ◽  
Complex Flow ◽  
Sound Channel ◽  
Georgian Bay ◽  
Water Currents ◽  
The Mean

Abstract Water exchange between Severn Sound and Georgian Bay was estimated by current measurements at 16 locations across the Severn Sound Channel from June to October 1988. An excursion episode model was employed to compute the exchange. The current measurements showed that the mean monthly speeds varied from 3.2 to 17.0 cm/s, while the maximum speed recorded was 95 cm/s. Vertical flows were found to be in the opposite direction at the upper and lower levels, particularly in the middle of the channel. A complex flow regime in the channel prevailed. The modelling showed that 0.31% of Severn Sound volume left the Sound daily towards Georgian Bay, while 0.26% of the volume entered the Sound through all inflows. The mean residence time for the Sound was estimated to be 69 days. In other words, water in the Sound is completely replaced in 69 days.

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