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Nonlinear single‐phase flow in real rock joints
Author(s) -
Ranjith P. G.,
Darlington W.
Publication year - 2007
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/2006wr005457
Subject(s) - overburden pressure , airflow , phase (matter) , materials science , flow (mathematics) , mechanics , linearity , geotechnical engineering , reynolds number , geology , thermodynamics , chemistry , engineering , physics , turbulence , organic chemistry , electrical engineering
Laboratory analysis of single‐phase water and airflow through a real rock joint under increasing confining pressure was carried out in order to assess the linearity or otherwise of the Reynolds number ( Re ) versus pressure change relationship and to also test the applicability of Forchheimer's relation. These tests were conducted on a granitic specimen, 110 mm high and 55 mm in diameter, with a single natural fracture running the height of the specimen, which had a matrix permeability of approximately 10 −18 m 2 . The single‐phase Re versus pressure change relationship using water was confirmed as being quadratic in nature. This same relationship held for single‐phase airflow but only for confining pressures below around 2.0 MPa. At confining pressures ≥3.0 MPa the relationship shifted in form to a cubic fit. In analyzing the application of Forchheimer's transmissivity relation to single‐phase water flow it was concluded that the model was appropriate for all tested confining pressures (0.55–3.0 MPa). When assessing its applicability to single‐phase airflow, the model was only accurate at low‐confining pressures (<1.0 MPa). Further, it was found that an increase in confining pressure shifted the Forchheimer's transmissivity curve downward.