Calculating groundwater response times for flow in heterogeneous porous media

Predicting the amount of time required for a transient groundwater response to take place is a practical question that is of interest in many situations. This time scale is often called the response time. In the groundwater hydrology literature there are two main methods used to calculate the response time: (i) both the transient and steady state groundwater flow equations are solved, and the response time is taken to be amount of time required for the transient solution to approach the steady solution within some tolerance; and (ii) simple scaling arguments are adopted. Certain limitations restrict both of these approaches. Here we outline a third method, based on the theory of mean action time. We derive the governing boundary value problem for both the mean and variance of action time for confined flow in two-dimensional heterogeneous porous media. Importantly, we show that these boundary value problems can be solved using widely available software. Applying these methods to a test case reveals the advantages of the theory of mean action time relative to standard methods.Comment: 15 pages, 2 Figure

Study of aerodynamic technology for single-cruise-engine V/STOL fighter/attack aircraft

A viable, single engine, supersonic V/STOL fighter/attack aircraft concept was defined. This vectored thrust, canard wing configuration utilizes an advanced technology separated flow engine with fan stream burning. The aerodynamic characteristics of this configuration were estimated and performance evaluated. Significant aerodynamic and aerodynamic propulsion interaction uncertainties requiring additional investigation were identified. A wind tunnel model concept and test program to resolve these uncertainties and validate the aerodynamic prediction methods were defined

Viscous fingering in miscible, immiscible and reactive fluids

With the Lattice Boltzmann method (using the BGK approximation) we investigate the dynamics of Hele-Shaw flow under conditions corresponding to various experimental systems. We discuss the onset of the instability (dispersion relation), the static properties (characterization of the interface) and the dynamic properties (growth of the mixing zone) of simulated Hele-Shaw systems. We examine the role of reactive processes (between the two fluids) and we show that they have a sharpening effect on the interface similar to the effect of surface tension.Comment: 6 pages with 2 figure, to be published in J.Mod.Phys

Nonlinear diffusion model for Rayleigh-Taylor mixing

The complex evolution of turbulent mixing in Rayleigh-Taylor convection is studied in terms of eddy diffusiviy models for the mean temperature profile. It is found that a non-linear model, derived within the general framework of Prandtl mixing theory, reproduces accurately the evolution of turbulent profiles obtained from numerical simulations. Our model allows to give very precise predictions for the turbulent heat flux and for the Nusselt number in the ultimate state regime of thermal convection.Comment: 4 pages, 4 figure, PRL in pres

Unconditional convergence and optimal error estimates of a Galerkin-mixed FEM for incompressible miscible flow in porous media

In this paper, we study the unconditional convergence and error estimates of a Galerkin-mixed FEM with the linearized semi-implicit Euler time-discrete scheme for the equations of incompressible miscible flow in porous media. We prove that the optimal $L^2$ error estimates hold without any time-step (convergence) condition, while all previous works require certain time-step condition. Our theoretical results provide a new understanding on commonly-used linearized schemes for nonlinear parabolic equations. The proof is based on a splitting of the error function into two parts: the error from the time discretization of the PDEs and the error from the finite element discretization of corresponding time-discrete PDEs. The approach used in this paper is applicable for more general nonlinear parabolic systems and many other linearized (semi)-implicit time discretizations

Statistics of precursors to fingering processes

We present an analysis of the statistical properties of hydrodynamic field fluctuations which reveal the existence of precursors to fingering processes. These precursors are found to exhibit power law distributions, and these power laws are shown to follow from spatial $q$-Gaussian structures which are solutions to the generalized non-linear diffusion equation.Comment: 7 pages incl. 5 figs; tp appear in Europhysics Letter

Preventing sexual violence in New Mexico: what our communities have to say.

Presented at: 2015 Annual Conference of the New Mexico Public Health Association; March 31-April 1, 2015; Albuquerque, NM.https://digitalrepository.unm.edu/prc-posters-presentations/1036/thumbnail.jp

ADULT LEARNING ON THE INTERNET: ENGAGING THE eBAY AUCTION PROCESS

The current revolution of the Information Age is rapidly changing the complexion of many personal and corporate societies. This revolution is changing the methods people use to communicate with each other, research new information, solve problems, and transact business. The purpose of this study was to describe the learning strategies that adults use in learning to engage in the eBay auction process. The study used the following research questions: (a) what are the identified learning strategy preferences of adult learners using eBay, (b) how do the learning strategy preferences of eBay users compare to the norms for ATLAS, and (c) how do eBay users describe their learning processes related to getting started on eBay, participating in eBay activities,communicating on eBay, learning through eBay, and experiencing eBay? This study used a descriptive design along with the information and data gathering advantages of the Internet to collect data about how adults learn using the Internet. An online questionnaire which featured 19 qualitative questions and 11 quantitative Likert scale items was used to determine the perceptions of eBay participants. Assessing The Learning Strategies of AdultS (ATLAS) instrument was imbedded within the online questionnaire to determine the preferred strategies of eBay users. The study involved a representative sample of 380 eBay users which was identified by electronically downloading the e-mail addresses of participants in completed auctions. The sample was stratified by the 13 categories of items listed on eBay. Within each of these categories, high-volume completed auctions were selected in which the final sale price was under $10, between$11 and $100, and over$100

Prospectus, January 10, 2001

https://spark.parkland.edu/prospectus_2001/1000/thumbnail.jp