Simulation of inviscid compressible multi-phase flow with condensation

Condensation of vapours in rapid expansions of compressible gases is investigated. In the case of high temperature gradients the condensation will start at conditions well away from thermodynamic equilibrium of the fluid. In those cases homogeneous condensation is dominant over heterogeneous condensation. The present work is concerned with development of a simulation tool for computation of high speed compressible flows with homogeneous condensation. The resulting flow solver should preferably be accurate and robust to be used for simulation of industrial flows in general geometries

Effluent salinity of pipe drains and tube-wells : a case study from the Indus plain

Keywords: anisotropy, aquifer, desalinization, effluent salinity, groundwater, irrigation, salt-water upconing, soil salinity, stream-function, subsurface drainageIrrigated agriculture in arid and semi-arid zones often suffers from waterlogging and salinity problems. Sub-surface drainage systems can be used to control the groundwater table and to facilitate the leaching of salts from the rootzone. In the Indus plain, pipe drains and tube-wells are used for this purpose. Regional water management requires that the development of the effluent salinity with time of these systems is known in advance. Numerical models based on the Darcy equation and the mass balance equation for water flow and the advection-dispersion equation for solute transport are powerful tools to predict the effluent salinity of pipe drains and tube-wells at field level. In advection-dominated transport problems, however, solute impulse response functions based on stream-functions constitute a more computationally efficient approach.A new modelling approach is presented that combines the one-dimensional vertical finite-difference SWAP model for the variably saturated zone with a solute impulse response function for the saturated zone. This approach is applied to the Sampla experimental pipe drainage site in Haryana, India, the S-I-B-9 pipe drainage unit of the Fourth Drainage Project, Punjab, Pakistan and the Satiana tube-well Pilot Project, Punjab, Pakistan. Results show that the effluent salinity of pipe drains and tube-wells changes only gradually with time due to the low percolation from the irrigated fields and due to the large quantities of salts stored in the groundwater. Areas with relatively high percolation and a shallow depth of the impermeable layer (pipe drains at Sampla) still require 10 years before the effluent salinity has reduced to equilibrium levels. In contrast, desalinization of the rootzone generally takes only 1-3 years. The implication is that farmers will benefit quickly from the installation of a drainage system. However, for the safe use and disposal of the effluent, long term solutions are required.In the Indus plain, groundwater salinity usually increases with depth. In water scarce areas, the shallow fresh groundwater may be an important source of irrigation water. In waterlogged areas, where sub-surface drainage is installed to control the groundwater table, the presence of fresh groundwater bodies may result in a relatively low effluent salinity. The finite-element model SUTRA is used to study the behaviour of skimming wells and pipe drains in fresh-saline groundwater systems. The model is calibrated on two documented experiments with a skimming well and a scavenger well at Phularwan research farm, Punjab, Pakistan. Salt water upconing below the skimming well is particularly sensitive to the anisotropy factor of the aquifer. The relationship between aquifer anisotropy and the Electrical Conductivity ( EC ) of the pumped water is non-linear. The skimming well simulations show that water with an EC of1.7 dS m -1can be pumped from a thin fresh groundwater body, provided that the pumping rate is low. Under the same circumstances, pipe drains yield a better effluent quality ( EC of 1.2-1.3 dS m -1). With pipe drains, flow is restricted to the shallow fresh groundwater. The deeper saline groundwater is left untouched. The better effluent quality for pipe drains as compared to skimming wells, must be evaluated against the considerably higher installation costs for pipe drains.</p

A FDR Sensor for Measuring Complex Soil Dielectric Permittivity in the 10–500 MHz Frequency Range

Mechanical details as well as electrical models of FDR (frequency domain reflectometry) sensors for the measurement of the complex dielectric permittivity of porous materials are presented. The sensors are formed from two stainless steel parallel waveguides of various lengths. Using the data from VNA (vector network analyzer) with the connected FDR sensor and selected models of the applied sensor it was possible obtain the frequency spectrum of dielectric permittivity from 10 to 500 MHz of reference liquids and soil samples of various moisture and salinity. The performance of the analyzed sensors were compared with TDR (time domain reflectometry) ones of similar mechanical construction

Coal-Bed Methane Water Effects on Dill and Its Essential Oils

Pumping water from coal seams decreases the pressure in the seam and in turn releases trapped methane; this is the most common and economic method of methane extraction. The water that is pumped out is known as "coal-bed methane water" (CBMW), which is high in sodium and other salts. In the past 25 yr, the United States has seen a 16-fold increase in the production of coal bed methane gas, and trillions of cubic meters are yet to be extracted. There is no sustainable disposal method for CBMW, and there are very few studies investigating the effects of this water on plants and their secondary metabolites and on soil properties. This study was conducted to determine the effects of CBMW on soil chemical properties and on the biomass and essential oil yield and composition of dill (Anethum graveolens L.). This crop was grown in a greenhouse and was subjected to different levels of CBMW treatment: tap water only; 25% CBMW, 75% tap water; 50% CBMW, 50% tap water; 75% CBMW, 25% tap water; and 100% CBMW. The major dill oil constituents, limonene and α-phellandrene, were not affected by the treatments; however, the concentration of dill ether increased with increasing CBMW levels, whereas the concentration of carvone decreased. In soil, sodium level significantly increased with increasing level of treatment, but pH and cation exchange capacity were not much affected. Coal bed methane water could be used for irrigation of dill for one growing season, but longer-term studies may be needed to clarify the long-term effects on soil and plant

Modeling the isotopic evolution of snowpack and snowmelt : Testing a spatially distributed parsimonious approach

This work was funded by the NERC/JPI SIWA project (NE/M019896/1) and the European Research Council ERC (project GA 335910 VeWa). The Krycklan part of this study was supported by grants from the Knut and Alice Wallenberg Foundation (Branch-points), Swedish Research Council (SITES), SKB and Kempe foundation. The data and model code is available upon request. Authors declare that they have no conflict of interest. We would like to thank the three anonymous reviewers for their constructive comments that improved the manuscript.Peer reviewedPublisher PD

Field Performance of Nine Soil Water Content Sensors on a Sandy Loam Soil in New Brunswick, Maritime Region, Canada

An in situ field test on nine commonly-used soil water sensors was carried out in a sandy loam soil located in the Potato Research Center, Fredericton, NB (Canada) using the gravimetric method as a reference. The results showed that among the tested sensors, regardless of installation depths and soil water regimes, CS615, Trase, and Troxler performed the best with the factory calibrations, with a relative root mean square error (RRMSE) of 15.78, 16.93, and 17.65%, and a r2 of 0.75, 0.77, and 0.65, respectively. TRIME, Moisture Point (MP917), and Gopher performed slightly worse with the factory calibrations, with a RRMSE of 45.76, 26.57, and 20.41%, and a r2 of 0.65, 0.72, and 0.78, respectively, while the Gypsum, WaterMark, and Netafim showed a frequent need for calibration in the application in this region