Thesis (M.S.)--University of Wisconsin--Madison, 1967. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.S.)--University of Wisconsin--Madison, 1984. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 146-149).

Thesis--Wisconsin. / Vita. Includes bibliographical references (leaves 226-230).

The detection of trace explosives in the subsurface is an active area of research for landmine detection. Understanding the air-water flow and heat transport phenomena in the subsurface plays an important role in improving chemical vapor detection. Implementing a finite element method that accurately captures water vapor transport in the vadose zone is still an open question. A non-equilibrium, pressure-pressure formulation has been implemented based on Smits, et al [22]. This implementation consists of four equations: a wetting phase (water) mass balance equation, a non-wetting phase (air) mass balance equation, a water vapor transport equation, and a heat transport equation. This work will compare two implementations, a fully coupled approach and an operator splitting approach for the water vapor and heat transport equations. The formulation of the methods will be presented and the methods will be tested using collected data from physical experiments.

Evaporation synergy is the phenomenon in which two porous medium textures that share a common vertical boundary experience a higher cumulative evaporation than either homogeneous texture can produce. Studies that have been conducted to date address this phenomenon in relatively fine and coarse sands but not in finer textured soils where viscous forces play a major role. The purpose of this study was to determine which of the 66 combinations of soil textures would exhibit evaporation synergy and develop a conceptual model of the conditions necessary for synergy. The numerical modeler HYDRUS was used to investigate all soil texture combinations and generate evaporation rates and cumulative evaporation amounts for each system. In addition, two combinations of soils were selected as laboratory experiments based on the HYDRUS predictions: one that exhibited synergy (Loamy Sand & Silt Loam) and one that did not (Loamy Sand & Sandy Clay). The laboratory data supported the HYDRUS predictions for evaporation synergy and non-synergy. The conditions necessary for evaporation synergy were developed from the numerical and physical models��� predictions and results. The two textures must experience different air-entry values to create lateral and vertical pressure gradients, the fine must possess a high enough hydraulic conductivity to allow water to move to its surface before it reaches its own air-entry value and possess the capillarity to maintain liquid film flow to its surface, and the viscous forces within the coarse must be low enough for water to be pulled from itself to the fine. It was also determined that the evaporation rate of a bi-texture decreases as a series of constant-rate steps until the fine enters S2 evaporation and is associated with a stepwise recession of the drying front in the coarse media. The duration of each step appears to be associated with the lateral distance from which water can be extracted within the coarse media. / Graduation date: 2013

No description available.

The purpose of this work was to investigate the evaporation rates of various brines and to compare them to the evaporation rates of pure water under the same environmental conditions in the laboratory. NaCl, MgCl 2 and KCl were the salts used in the experiments, at three densities. Mixtures of the salts were also used. One set of experiments was conducted under free convection while the other was conducted under forced convection, both over pans. Temperature was relatively constant for the experiments but relative humidity was not controlled. Wind profiles were measured during the forced convection experiments and an aerodynamic equation used to calculate evaporation for comparison with the observed evaporation rates. Surface temperatures were also measured. Water activities of all the brine and brine mixtures were also measured and compared to predictions by Raoult's law. In general, it was found the evaporation rate of brines was lower than that of pure water and that the water activities and evaporation rates were density-dependent to a certain extent. More precisely, they were dependent on the actual constituents in the brine due to the different molecular weights, and the number of ions dissolving from a given weight of salt or salt mixture. Evaporation rates can better be estimated on this basis than on the basis of density alone, as one would expect from Raoult's Law.

No description available.

Technical Bulletin 177 / October 1966 / Final Report on Evaporation Reduction Investigation Relating to Small Reservoirs, 1963-65 / Contract No. 14-06-D-5045 / By C. Brent Cluff / Prepared for The Bureau of Reclamation, U.S. Department of the Interior / Submitted by The Institute of Water Utilization, Agricultural Experiment Station, The University of Arizona, Tucson, Arizona.

<b>Structure of the thesis</b> The present work has been organized in two main parts: in the first one, the focus will be on the scientific and theoretical aspects of the evaporation process in presence of an inert gas flow while in the second all the technical aspects and more practical tests related to the real implementation of the micro-gravity experiment CIMEX-1 will be detailed. In any cases, the discussion will always start from the phenomenology observed considering that ” Nature is far more reach of any speculations.” <b>Part I: Evaporation in presence of inert gas</b> In chapter 1, a detailed presentation of the experimental setups for the on-ground tests is given together with the presentation of the qualitative and quantitative results obtained. Actually, the main parameters that regulate such kind of experiments are the mass flow rate of inert gas, the total pressure of the cell and the geometrical shape and dimensions of the evaporating regions. Consequently, the experiments aimed at covering the maximal possible combination of these three parameters with special attention to the variation of the inert gas flow and of the thickness of the evaporating liquid layer. More precisely, the liquid layer thickness was in the range 1.2 to 3.8 mm while the inert gas flow was set in the range 50 to 2500 ml/min. The pressure has been partially neglected as control parameter because its control was discovered not to be very reliable. The visualization system used in all the experiments consisted in a opportunely calibrated infrared camera. It allowed for having a quantitative analysis of the temperature distribution at the interface of the evaporating liquid. The infrared images also helped to follow the thermal history of the interface. In many cases, it has been possible to clearly observe the evolution of instability patterns at the interface that represent an original contribution to the understanding of such a kind of phenomena. The physical and mathematical modeling of the observed phenomenology will be the subject of the chapter 2. One of the peculiar issue of the problem under consideration is that the thermal gradient normal to the interface is not directly imposed like in the usual Marangoni-Bénard experience, but is a result of the cooling of the interface due to the evaporation. Moreover,the interface is subject to the shear stress of the inert gas flow and to the one due to the thermo-capillarity. Finally, the gas phase is to be considered as a mixture; this oblige to solve a diffusion problem in the gas phase. A physical model that takes into account the different aspects mentioned above is presented together with the governing equations and the appropriate boundary conditions. Numerical issues involved in solving the model are also analyzed. Numerical results obtained are finally discussed and compared when possible with experimental results. <b>Part II: Preparation of the CIMEX-1 experiment on-board the International Space Station.</b> In chapter 3, we will describe the main platforms used to perform low-gravity experiments. They will be classified according to the low-gravity level and to the low-gravity interval duration that could be ensured for experiments. According to these criteria, the list of the low-gravity platforms will be as follows: Drop Towers with 4 sec. of micro-gravity, Parabolic Flights that can assure not more than 25 sec., Sounding Rockets with a low-gravity time of the order of several minutes depending on the rockets, Foton Capsules that assure for many days of high quality - i.e. without perturbations - low-gravity level and , last but not least, the International Space Station where the low-gravity duration could be even of several weeks which is a sufficient time duration for the most part of the experiments. The chapter 4 will be entirely devoted to the ITEL experiment that is the precursor and the core of the CIMEX-1. After a brief overview of the experiment that has been performed twice on-board sounding rockets of the MASER class, the experimental setups used both on-ground and in micro-gravity will be detailed. The focus will be on the experimental results obtained on-ground during the preparatory tests and during the two sounding rocket flights with special attention to the first one. The analysis will be supported by the presentation of many results obtained in numerical simulations. The two parabolic flight campaigns performed to test one of the key sub-systems of the CIMEX-1 setup are the subject of the chapter 5. The separating-condensing unit is mandatory for performing the experiment on-board the International Space Station because the limitations on the crew intervention oblige to have a closed loop experiment. The goal of the two parabolic flights will be detailed together with the setup and the experimental scenario. The main results will be also shown and some considerations on the efficiency of the system will be presented. It is worthy to stress that the results obtained during these parabolic flights have been determinant at the European Space Agency level to fly the CIMEX-1 experiment on-board the International Space Station. Finally, in the section conclusions and perspectives the main results obtained will be summarized together with the new scenarios opened by the present work and some guidelines for further development in the experimental, theoretical and technical analysis.