Type of Document	Dissertation
Author	Werner, Christopher Lee
Author's Email Address	werner@gfdi.fsu.edu
URN	etd-11052007-021403
Title	Double-diffusive fingering in porous media
Degree	Doctor of Philosophy
Department	Geophysical Fluid Dynamics Institute
Advisory Committee	Advisor Name Title Ruby Krishnamurti Committee Chair Georges Weatherly Committee Member James Tull Committee Member Jennifer Georgen Committee Member
Keywords	Convection Double Diffusion Fingering
Date of Defense	2007-04-03
Availability	unrestricted
Abstract Laboratory experiments were conducted on a double-diffusive fluid with components of dissolved salt and sucrose contained within a porous medium of nearly spherical glass beads. The fluid is stabilized by the faster diffuser (Sa) and destabilized by the slower diffuser (Su) arranged in such a way so that the system is finger-favorable. The experiments were conducted in a tank of depth 30 cm, with initial vertical opposing linear profiles of Sa and Su between two reservoirs, the top containing a Su solution and the bottom a Sa solution of known values. Measurements show that the Rayleigh-Darcy number experimental range is up to |Rsa|~10^5 and density ratio ranges from Rrho= 1.1 to 1.4 with spherical bead range of d = 0.01 to 0.80 cm. The finger flux for salt was Fsa~CRsa^a with a = 0.17 to 0.25 and was Fsu~CRsu^b with b = 0.12 to 0.14 for sugar. The spacing of the fingers was measured and non-dimensionalized using the height of the test reservoir. The non-dimensional spacing lambda was found to be related to the salt Rayleigh-Darcy number lambda~Rsa^m with m = -0.31 for glass bead size d = 0.05 cm and m = -0.55 for d = 0.10 cm and related to the sucrose Rayleigh-Darcy number lambda~Rsu^n with n = -0.41 for d = 0.05 cm and n = -0.69 for d = 0.10 cm, compared to the prediction of lambda~Rsa^0.5 from linear theory.
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