Navigation Links
Where does the fluid go?
Date:2/24/2010

MADISON, WI, FEBRUARY 22, 2010 Combined mechanisms of transport have important applicationstransport of nutrients across cell membranes in plants and animals, the aeration of agricultural soils, performance of chemical reactors, the design of membranes for desalting brackish water, and the design of clay membranes for retaining dangerous chemicals. Because mass transport of fluid constituents has important roles in biology, physics, and chemistry, one would assume that such transport would be well understood by the scientific community. However, transport of fluid constituents continues to be a source of confusion, particularly regarding models for combining transport by molecular diffusion and advection.

In a recent article in Vadose Zone Journal, A.T. Corey, W.D. Kemper (both of Colorado State Univ., Fort Collins), and J.H. Dane (Auburn Univ., Auburn, AL) show that the developers of popular models of diffusion have made invalid assumptions. Currently popular models define diffusion of a particular constituent as a flux relative to mass average flux so that diffusive flux of all constituents in a fluid mixture must sum to zero, and self-diffusion of a single-specie fluid cannot exist, contradicting experimental evidence previously reported in the literature. Research conducted and referenced by the authors shows that these assumptions and their models do not provide a satisfactory description of the flux taking place in media with small pores. The authors provide an improved analysis, based on the principle that driving forces (for both advection and diffusion) are each equal in magnitude (and opposite in direction) to the associated rate of change of momentum. Mass average flux resulting from combined advection and diffusion is shown to be evaluated as the vector sum of advective and diffusive fluxes, rather than diffusive flux being evaluated as a flux relative to a mass average flux. This procedure is necessary because "mean flux" cannot be determined independent of an evaluation of diffusive flux.

Corey et al. describe two experiments with transport of gas constituents through porous media (providing data consistent with their revised model) that contradict widely accepted models. One of the experiments presents previously published data and the other describes new data obtained by the authors. Three additional experiments are presented (one representing new data) showing that self-diffusion of pure liquid water occurs in response to a temperature gradient, contradicting theory that diffusion of a single-specie fluid cannot occur, and showing that the sum of diffusion fluxes do not sum to zero in the general case. The measured diffusion of water was proportional to the gradient of the vapor pressure, which is a well-documented measure of the kinetic energy of water.


'/>"/>

Contact: Sara Uttech
suttech@sciencesocieties.org
608-268-4948
American Society of Agronomy
Source:Eurekalert

Related medicine news :

1. The Doctor Is in...But Where Is the Tax Advisor?
2. Using gold nanoparticles to hit cancer where it hurts
3. For Valentine's Day, Lifestyle Correspondent and Her Two Sets of Twins Show a Little Love Where Its Needed the Most
4. Dog Flu Risk Highest Where Canines Mingle
5. How does an outfielder know where to run for a fly ball?
6. It's January...Do You Know Where Your Thyroid Is? Thyroid Awareness Month Focuses on Millions of Undiagnosed Americans with Thyroid Problems
7. New Study Says Doctors' Offices -- Not the DMV -- Should Be Where Americans Decide to Become Organ Donors
8. Duda, whered my spines go?
9. Children & Health Reform: Where We Stand
10. The importance of attractiveness depends on where you live
11. Blue Cross and Blue Shield of Minnesota and Fairview Health Services Launch Online Care Anywhere(TM)
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:2/23/2017)... ... February 23, 2017 , ... ... host a diverse symposium on “Doping in Sport: How the Culture Might ... Richter & Hampton LLP. The symposium will be held at Pepperdine University in ...
(Date:2/23/2017)... ... February 23, 2017 , ... ... in clinical trials, today announced that Premier Research, a leading clinical development service ... Clinical trials are becoming increasingly complex, due in part to an array of ...
(Date:2/23/2017)... ... February 23, 2017 , ... The ... the Rhode Island Consortium for Autism Research and Treatment (RI-CART) and Cinemaworld to ... autism spectrum disorder (ASD) to see films in an environment that accommodates their ...
(Date:2/23/2017)... Los Angeles, CA (PRWEB) , ... February 23, 2017 , ... ... of her Smiling Patriot program today with a new Indiegogo campaign ... dental care to homeless veterans in the Los Angeles area, either as a participating ...
(Date:2/23/2017)... (PRWEB) , ... February 23, 2017 , ... Thomas ... perseverance and disciplined exercise regime, the author was able to successfully recover. In “ ... all relevant information for various sources on the principals of massage, anatomy , ...
Breaking Medicine News(10 mins):
(Date:2/23/2017)... JOLLA, Calif. , Feb. 23, 2017 ... company leading the discovery and development of innovative medicines ... and full year 2016 financial results on Thursday, March ... will host a conference call and webcast on March ... fourth quarter and full year 2016 financial results and ...
(Date:2/23/2017)... -- ... Research and Markets has announced the addition of the "Global Antifungal ... to their offering. The Global Antifungal Drugs Market is ... decade to reach approximately $12.8 billion by 2025. ... given segments on global as well as regional levels presented in the ...
(Date:2/23/2017)... Group, Inc. (NASDAQ: MDXG), the leading regenerative medicine company ... and market advanced products and therapies for the Wound ... sectors of healthcare, today announced its record results for ... 2016. Full Year 2016 Highlights are: ... full year 2015 revenue ...
Breaking Medicine Technology: