Premium
Effect of the flow state on streaming current
Author(s) -
Kuwano Osamu,
Nakatani Masao,
Yoshida Shingo
Publication year - 2006
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2006gl027712
Subject(s) - current (fluid) , state (computer science) , flow (mathematics) , streaming current , geology , environmental science , mechanics , computer science , physics , materials science , oceanography , algorithm , nanotechnology , electrokinetic phenomena
When a fluid flows through a porous medium, charges in the electric double layer are transported, resulting in a streaming current. This is the representative mechanism of self‐potential widely observed in the field. In the conventional Helmholtz‐Smoluchowski relation, the streaming current density ( i s ) is represented as i s = C c grad P p , where C c is the streaming current coefficient and P p is the fluid pressure. C c depends on the hydraulic property of the rock and the electrochemical property called the zeta potential. It was shown that the streaming current coefficient was clearly affected by the flow state: it was constant at a low Reynolds number R e , but decreased at R e > 1–10. This is a mechanical effect (i.e., smaller apparent permeability for nonlinear laminar flow), not a chemical effect on the zeta potential. The mutually contradicting values of zeta potential, which is calculated from measured C c , obtained in different studies may be due to this effect. In addition, we found that the decreasing rate of C c with increasing R e is much less than that of permeability. This means that nonlinear laminar flow induces more streaming current per unit flow rate.