scholarly journals Density Slopes in Variable Density Flow Modeling

Water ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 3292
Author(s):  
Weixing Guo
Keyword(s):  
Variable Density ◽  
Quality Data ◽  
Constant Density ◽  
Fluid Density ◽  
Concentration Data ◽  
Modeling Tools ◽  
Water Quality Data ◽  
Variable Density Flow ◽  
Density Flow ◽  
Density Modeling

Variable density flow (VDF) modeling is a valuable tool for assessing the potential impacts of global climate change and sea level rise on coastal aquifers. When using any of these modeling tools, a quantitative relationship is needed to compute the fluid density from salt concentration. A full understanding of the relationship between fluid density and solute concentration and the correct implementation of the equation of state are critical for variable density modeling. The works of Baxter and his colleagues in the early 20th century showed that fluid density could be linearly correlated to salt concentrations. A constant density slope of 0.7 is often assumed and applied. The assumption is reasonable when the salinity is less than 100‰. The density slope can also be defined from chloride concentration data with the assumption of a constant ratio (55%) between chloride and total dissolved solids (TDS). Field data from central Florida indicate that the chloride/TDS ratio can be as low as 5%. Therefore, TDS is the preferred water quality data for fluid density determination in variable density modeling. Other issues with density slope are also discussed, and some commonly used values of density slope are provided in this technical note.

A semi-Lagrangian direct-interaction closure of the spectra of isotropic variable-density turbulence

2019 ◽  
Vol 876 ◽  
pp. 186-236 ◽  
Author(s):  
David J. Petty ◽  
C. Pantano
Keyword(s):  
Large Scale ◽  
Isotropic Turbulence ◽  
Density Ratio ◽  
Direct Interaction ◽  
Variable Density ◽  
Constant Density ◽  
Velocity Spectrum ◽  
Variable Density Flow ◽  
Density Flow ◽  
Variable Density Turbulence

A study of variable-density homogeneous stationary isotropic turbulence based on the sparse direct-interaction perturbation (SDIP) and supporting direct numerical simulations (DNS) is presented. The non-solenoidal flow considered here is an example of turbulent mixing of gases with different densities. The spectral statistics of this type of flow are substantially more difficult to understand theoretically than those of the similar solenoidal flows. In the approach described here, the nonlinearly coupled velocity and scalar (which determine the density of the fluid) equations are expanded in terms of a normalised density ratio parameter. A new set of coupled integro-differential SDIP equations are derived and then solved numerically for the first-order correction to the incompressible equations in the variable-density expansion parameter. By adopting a regular expansion approach, one obtains leading-order corrections that are universal and therefore interesting in their own right. The predictions are then compared with DNS of forced variable-density flow with different density contrasts. It is found that the velocity spectrum owing to variable density is indistinguishable from that of constant-density turbulence, as it is supported by a wealth of indirect experimental evidence, but the scalar spectra show significant deviations, and even loss of monotonicity, as a function of the type and strength of the large-scale source of the mixing. Furthermore, the analysis helps clarify what may be the proper approach to interpret the power spectrum of variable-density turbulence.

Numerical Verification of the Solutions for Groundwater Flow in a Coastal Extensive Land Mass

2013 ◽  
Vol 864-867 ◽  
pp. 2292-2297
Author(s):  
Hai Peng Guo
Keyword(s):  
Analytical Solutions ◽  
Land Reclamation ◽  
Variable Density ◽  
Numerical Code ◽  
Numerical Verification ◽  
Variable Density Flow ◽  
Density Flow ◽  
Type Flow ◽  
Land Mass ◽  
The Impact

This paper reviews the analytical solutions for the impact of land reclamation on the ground water level and the saltwater interface with unconfined groundwater conditions in coastal aquifers. The applicability of the analytical solutions is somewhat limited by assumptions such as Dupuit-type flow and the Ghyben-Herzberg relation. Variable-density flow and solute transport simulations conducted by the numerical code FEFLOW were used to evaluate the accuracy of these analytical solutions. Three field-scale hypothetical cases were simulated for the numerical verification. The results show that a seepage face occurs in the numerical results rather than in the analytical solutions, but only minor difference occurs between the numerical and analytical solutions. This implies that the analytical solutions are reasonable despite the used assumptions.

On the generation of instabilities in variable density flow

1994 ◽  
Vol 30 (4) ◽  
pp. 913-927 ◽  
Author(s):  
Robert A. Schincariol ◽  
Franklin W. Schwartz ◽  
Carl A. Mendoza
Keyword(s):  
Variable Density ◽  
Variable Density Flow ◽  
Density Flow

scholarly journals Experimental and Numerical Studies on the Vertical Flow of Variable Density Fluid in Different Directions

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-15
Author(s):  
Zhifang Zhou ◽  
Boran Zhang ◽  
Qiaona Guo ◽  
Shumei Zhu
Keyword(s):  
Salt Water ◽  
Water Injection ◽  
Experimental Studies ◽  
Engineering Application ◽  
Variable Density ◽  
Vertical Flow ◽  
Construction Time ◽  
One Dimensional ◽  
Variable Density Flow ◽  
Density Flow

Injecting freshwater and pumping salt water are effective methods to restore the salt water in a coastal area. Based on a one-dimensional vertical experiment, the variable density flow is simulated under the condition of different injection directions and injection rates of fresh water. A one-dimensional mathematical model of variable density flow and solute transport is established. The mathematical models are solved using the implicit difference method. Fortran code is developed to simulate and verify the vertical flow of variable density flow in different directions. Through both numerical simulation and experimental studies, it is found that the variable density fluid in the direction of reverse gravity is different from that in the direction of gravity. On this basis, the most effective desalination model of salt water is further discussed. It provides a theoretical and technical method for the restoration of salt water in the vertical injection of freshwater. In order to improve the remediation efficiency and reduce the cost in the engineering application, the suitable water injection rate should be ensured, considering the suitable construction time and zone of a study area.

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