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New injection experiments in non‐Newtonian fluids
Author(s) -
Hallot E.,
Auvray B.,
Bremond d'Ars J.,
Martin H.,
Davy Ph.
Publication year - 1994
Publication title -
terra nova
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.353
H-Index - 89
eISSN - 1365-3121
pISSN - 0954-4879
DOI - 10.1111/j.1365-3121.1994.tb00495.x
Subject(s) - newtonian fluid , rheology , non newtonian fluid , magma chamber , magma , geology , planar , homogeneous , density contrast , mechanics , materials science , thermodynamics , composite material , geotechnical engineering , volcano , physics , geochemistry , computer graphics (images) , astronomy , computer science
In order to identify the dominant non‐Newtonian effects which occur during the injection of a new Newtonian magma through a partially crystallized magma chamber, we have performed some preliminary analogue experiments which enable us to point out several features induced by the non‐Newtonian properties of the host fluid during injection processes. These experiments were performed in a three‐dimensional device and involve complex non‐Newtonian fluids—clay suspensions in which rheological properties such as bulk strength, yield strength and rheofluidification exponent may vary. Forced injection takes place through a slot which in the case of a Newtonian host fluid is the geometry that provides planar structures. Depending both on the density contrast and on the rheological contrast between the injected dyed water and the host fluid three kind of structures were observed: (1) permanent plumes when the injected water is lighter than the suspension exhibiting rheological properties close to Newtonian fluids; (2) pseudo‐fountains and spreading at the bottom of the tank with a destabilizing density contrast and in high yield strength/more viscous suspensions; (3) fountains with a slightly stablizing density contrast. The implications for magma chamber evolution are briefly discussed. In particular it seems that homogeneous non‐Newtonian media inhibit the formation of planar structures and partially crystallized magma may induce the spreading of the new magma at the bottom or at the top of the chamber regardless of the density contrast between the magmas.