scholarly journals Effects of aquifer geometry on seawater intrusion in annulus segment island aquifers

2021 ◽  
Vol 25 (12) ◽  
pp. 6591-6602
Author(s):  
Zhaoyang Luo ◽  
Jun Kong ◽  
Chengji Shen ◽  
Pei Xin ◽  
Chunhui Lu ◽  
...  
Keyword(s):  
Experimental Data ◽  
Sensitivity Analysis ◽  
Steady State ◽  
Seawater Intrusion ◽  
Analytical Solutions ◽  
Boussinesq Equations ◽  
Flow Boundary ◽  
Circle Center ◽  
Aquifer Geometry ◽  
Opposite Tendency

Abstract. Seawater intrusion in island aquifers was considered analytically, specifically for annulus segment aquifers (ASAs), i.e., aquifers that (in plan) have the shape of an annulus segment. Based on the Ghijben–Herzberg and hillslope-storage Boussinesq equations, analytical solutions were derived for steady-state seawater intrusion in ASAs, with a focus on the freshwater–seawater interface and its corresponding watertable elevation. Predictions of the analytical solutions compared well with experimental data, and so they were employed to investigate the effects of aquifer geometry on seawater intrusion in island aquifers. Three different ASA geometries were compared: convergent (smaller side is facing the lagoon, larger side is the internal no-flow boundary and flow converges towards the lagoon), rectangular and divergent (smaller side is the internal no-flow boundary, larger side is facing the sea and flow diverges towards the sea). Depending on the aquifer geometry, seawater intrusion was found to vary greatly, such that the assumption of a rectangular aquifer to model an ASA can lead to poor estimates of seawater intrusion. Other factors being equal, compared with rectangular aquifers, seawater intrusion is more extensive, and watertable elevation is lower in divergent aquifers, with the opposite tendency in convergent aquifers. Sensitivity analysis further indicated that the effects of aquifer geometry on seawater intrusion and watertable elevation vary with aquifer width and distance from the circle center to the inner arc (the lagoon boundary for convergent aquifers or the internal no-flow boundary for divergent aquifers). A larger aquifer width and distance from the circle center to the inner arc weaken the effects of aquifer geometry, and hence differences in predictions for the three geometries become less pronounced.

scholarly journals Effects of aquifer geometry on seawater intrusion in annulus segment island aquifers

2021 ◽  
Author(s):  
Zhaoyang Luo ◽  
Jun Kong ◽  
Chengji Shen ◽  
Pei Xin ◽  
Chunhui Lu ◽  
...  
Keyword(s):  
Experimental Data ◽  
Steady State ◽  
Seawater Intrusion ◽  
Analytical Solutions ◽  
Boussinesq Equations ◽  
Flow Boundary ◽  
Aquifer Geometry

Abstract. Seawater intrusion in island aquifers is considered analytically, specifically for annulus segment aquifers (ASAs), i.e., aquifers that (in plan) have the shape of an annulus segment. Based on the Ghijben-Herzberg and hillslope-storage Boussinesq equations, analytical solutions are derived for steady-state seawater intrusion for ASAs, with a focus on the freshwater-seawater interface and its corresponding watertable elevation. These analytical solutions, after comparing their predictions with experimental data, are employed to investigate the effects of aquifer geometry on seawater intrusion in island aquifers. Three different geometries of ASA are compared: convergent (smaller side facing the lagoon), rectangular and divergent (larger side facing the sea). The results show that the predictions from the analytical solutions are in well agreement with the experimental data for both recharge events. In addition, seawater intrusion is most extensive in divergent aquifers, and conversely for convergent aquifers. Accordingly, the watertable elevation is lowest in divergent aquifers and highest in convergent aquifers. Moreover, the effects of aquifer geometry on the freshwater-seawater interface and watertable elevation vary with aquifer width and distance to the no-flow boundary. Both a larger aquifer width and distance to the no-flow boundary weaken the effects of aquifer geometry and hence lead to a smaller deviation of seawater intrusion between the three geometries.

scholarly journals Towards a Correlation between Long-Term Seawater Intrusion Response and Water Level Fluctuations

Water ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 719
Author(s):  
Antoifi Abdoulhalik ◽  
Ashraf A. Ahmed ◽  
Abdelrahman M. Abdelgawad ◽  
G. A. Hamill
Keyword(s):  
Sensitivity Analysis ◽  
Steady State ◽  
Linear Relationship ◽  
Water Level ◽  
Linear Function ◽  
Seawater Intrusion ◽  
Water Level Fluctuations ◽  
Management Perspective ◽  
Perform Sensitivity Analysis ◽  
Water Level Variations

Laboratory and numerical experiments were conducted to provide a quantitative steady-state analysis of the effect of incremental variations of water level on saltwater intrusion. The purpose was to seek mathematical correlations relating both the wedge toe length and the height along the coastline to the boundary head difference. The laboratory experiments were completed in a 2D sand tank where both freshwater and seawater levels were varied. The experiments were conducted for two bead sizes having different hydraulic conductivities. The numerical model SEAWAT was used to validate the results and then to perform sensitivity analysis. The experimental results show that at steady-state conditions, the logarithmic toe length could be expressed as a linear function of the boundary head difference. The linear relationship was recorded in both advancing and receding wedge phases. The linearity of the correlation was also well demonstrated with analytical solutions. Similar relationships were also derived in the scenarios where the sea level fluctuated while the freshwater boundary head was constant. The height of the saltwater wedge along the coastline was also found to be a linear function of the boundary head difference. The sensitivity analysis shows that the regression coefficients were sensitive to the hydraulic conductivity, the dispersivity, and the saltwater density, while the porosity and the rate of boundary head change induced negligible effects. The existence of a linear relationship between the logarithmic toe length and the boundary head difference was also well evidenced in a field-scale aquifer model for all the different hydrogeological aquifer conditions tested. This study is the first attempt in identifying the underlying correlation between the boundary water level variations and the main seawater intrusion (SWI) external metrics under controlled laboratory conditions, which is of great relevance from a water resources management perspective.

scholarly journals EXTENDED BOUSSINESQ EQUATIONS FOR WAVES IN TWO POROUS LAYERS

2018 ◽  
pp. 92
Author(s):  
Changhoon Lee ◽  
Van Nghi Vu ◽  
Tae-Hwa Jung ◽  
Thanh Thu Huynh
Keyword(s):  
Experimental Data ◽  
Porous Layer ◽  
Analytical Solutions ◽  
Water Waves ◽  
Royal Society ◽  
Boussinesq Equations ◽  
Water Layer ◽  
Boussinesq Model ◽  
Porous Layers ◽  
Good Agreement

In this study we continue the work of Vu et al. (2018) [Coastal Eng. 139, 85-97] to develop an extended Boussinesq model that predicts the propagation of water waves in two porous layers. The first and second layer can be a water layer or a porous layer. The inertial and drag resistances are considered in the developed model. After being successfully validated against the analytical solutions, the model is used to simulate waves propagating over a submerged triangular porous bar. The numerical results show good agreement with the physical experimental data of Hsiao et al. (1998) [Proc. Royal Society of London A 458, 1291-1322].

Kinetic analysis of mechanism of intestinal Na+-dependent sugar transport

1985 ◽  
Vol 248 (5) ◽  
pp. C498-C509 ◽  
Author(s):  
D. Restrepo ◽  
G. A. Kimmich
Keyword(s):  
Experimental Data ◽  
Steady State ◽  
Sugar Transport ◽  
Enzyme Kinetic ◽  
Steady State Distribution ◽  
State Distribution ◽  
Least Squares Fit ◽  
Coupling Stoichiometry ◽  
Rate Limiting ◽  
Kinetics Of

Zero-trans kinetics of Na+-sugar cotransport were investigated. Sugar influx was measured at various sodium and sugar concentrations in K+-loaded cells treated with rotenone and valinomycin. Sugar influx follows Michaelis-Menten kinetics as a function of sugar concentration but not as a function of Na+ concentration. Nine models with 1:1 or 2:1 sodium:sugar stoichiometry were considered. The flux equations for these models were solved assuming steady-state distribution of carrier forms and that translocation across the membrane is rate limiting. Classical enzyme kinetic methods and a least-squares fit of flux equations to the experimental data were used to assess the fit of the different models. Four models can be discarded on this basis. Of the remaining models, we discard two on the basis of the trans sodium dependence and the coupling stoichiometry [G. A. Kimmich and J. Randles, Am. J. Physiol. 247 (Cell Physiol. 16): C74-C82, 1984]. The remaining models are terter ordered mechanisms with sodium debinding first at the trans side. If transfer across the membrane is rate limiting, the binding order can be determined to be sodium:sugar:sodium.

scholarly journals Simulative investigation of ring creep on a planetary bearing of a wind turbine gearbox

2021 ◽  
Author(s):  
Jonas Gnauert ◽  
Felix Schlüter ◽  
Georg Jacobs ◽  
Dennis Bosse ◽  
Stefan Witter
Keyword(s):  
Experimental Data ◽  
Finite Element Method ◽  
Sensitivity Analysis ◽  
Planetary Gear ◽  
The Finite Element Method ◽  
Relative Movement ◽  
Wind Turbine Gearbox ◽  
Interference Fit ◽  
Planetary Gears ◽  
Module Coefficient

AbstractWind turbines (WT) must be further optimized concerning availability and reliability. One of the major reasons of WT downtime is the failure of gearbox bearings. Some of these failures occur, due to the ring creep phenomenon, which is mostly detected in the planetary bearings. The ring creep phenomenon describes a relative movement of the outer ring to the planetary gear. In order to improve the understanding of ring creep, the finite element method (FEM) is used to simulate ring creep in planetary gears. First, a sensitivity analysis is carried out on a small bearing size (NU205), to characterize relevant influence parameters for ring creep—considered parameters are teeth module, coefficient of friction, interference fit and normal tooth forces. Secondly, a full-scale planetary bearing (SL185030) of a 1MW WT is simulated and verified with experimental data.

scholarly journals Analytical solutions for steady state vertical infiltration

2002 ◽  
Vol 38 (8) ◽  
pp. 20-1-20-5 ◽  
Author(s):  
Jianting Zhu ◽  
Binayak P. Mohanty
Keyword(s):  
Steady State ◽  
Analytical Solutions
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