Data/hora: 20/04/2024 02:08:34

Biblioteca(s): 	Embrapa Instrumentação.	
Data corrente: 	22/12/1999	
Data da última atualização: 	03/08/2009	
Autoria: 	CRESTANA, S.; POSADAS, A. N.	
Afiliação: 	EMBRAPA-CNPDIA; Universidade de Ponta Grossa.	
Título: 	2-D and 3-D fingering in unsaturated soils investigated by fractal analysis, invasion percolation modeling and non-destructive image processing.	
Ano de publicação: 	1998	
Fonte/Imprenta: 	In: BAVEYE, P.; PARLANGE, J.Y.; STEWART, B.A., (Ed.). Fractals in soil science. Boca Raton: CRC, 1998. p.293-332.	
Série: 	(Advances in Soil Science).	
ISBN: 	1-56670-105-8	
Idioma: 	Inglês	
Conteúdo: 	In this chapter we described current scientific research in relation to fingering phenomena in soils, as well as applications of fractal theory, invasion percolation theory and imaging techniques as non-desctructive and advanced methods in the study of such phenomena. Those studies showed that the perimeter of the finger displacement fronts represents a behavior of "self-affine" fractal or fractal type, its fractal dimension Dp being dependent on the time and the position along the profile of the soil column. Through the fractal dimension, it was also evident that the "dynamic" surface tension is dependent on Dp and the average pore diameter of the porous system. On the other hand, it was verified, by means of several experiments, that the fractal characteristics of the fingers, under the same initial conditions, are related to the soil granulometry or the pore-size distribution. For fine-textured soils the structure of the fingers presents statistically self-affine or fractal characteristics. In addition to these results, it was also possible to introduce a modified theory of invasion percolation, so as to simulate the fingers structure. The tomography and imaging techniques employed are already available, through nuclear magnetic resonance as well as through X-ray, and presented very innovative and encouraging results for the study of fingering phenomena in soils and porous media in general, allowing us, among other things, to witness, non-destructively, the three-dimensional and aleatory character of the phenomena. Nevertheless, great research challenges remain. It is needed, for instance, to better relate the "effective" surface tension to the fractal dimension of the fingers, the passage from non-fractality to the fractal behavior of the finger structure in relation to the soil granulometry, and the pore profile distribution to the phenomenon occurrence. Concomitantly, the exploration and the development of more appropriate methods to measure their morphological and physical characteristics, in 2 and 3 dimensions, establish an important challenge to be faced in the near future.	
Palavras-Chave: 	Ciencia do solo; Fractais; Fractals; Image processing; Modelamento; Modeling; Processamento de imagem; Solos nao-saturados; Unsaturated soils.	
Thesaurus Nal: 	soil science.	
Categoria do assunto: 	--	
Registro original: 	Embrapa Instrumentação (CNPDIA)	
Exemplares: 	CNPDIA - (5733-1) - UPC - SP - -- - PROCI-98.00035 -  - 1998.00035 - DIS