Experimental analysis of slug regimes using kymography.
Hannah Calleja1 , Eric Breard1, Tom D Pering2, Ian Butler1, Linda A Kirstein1, J Godfrey Fitton1
Affiliations: 1School of GeoSciences, University of Edinburgh, Edinburgh, UK; 2Department of Geography, University of Sheffield, Sheffield, UK
Presentation type: Poster
Presentation time: Monday 16:30 - 18:30, Room Poster Hall
Poster Board Number: 205
Programme No: 3.6.10
Abstract
Gas slugs, or Taylor bubbles, are massive bubbles that drive discrete and cyclic Strombolian explosions. This style of eruption is one of the most widespread expressions of uninterrupted basaltic sub-aerial volcanism globally. To understand the mechanisms driving observable surface eruption dynamics, we must first understand the flow dynamics in the shallow (<1 km depth) plumbing system. Our current knowledge of the fluid dynamics of ascending slug trains in volcanic conduits is built upon an extensive foundation of experimental studies, where bubbles behave similarly to those in low-viscosity basaltic magmas. Understanding how slugs flow in pipes is important to many fields, and thus the accurate measurement and analysis of their parameters is equally essential. Here, we introduce a novel application of kymography -- an existing digital image processing technique typically used to track micron-scale processes in biological and medical research -- for use in the measurement of continuous slug flow in cylindrical pipes. Kymographs allow the flow processes that are captured across thousands of frames of experimental footage to be represented as space-time data in a single image. We describe the method for generating and analysing kymographs from flow experiment footage using the freely accessible image analysis software ImageJ. Kymographs are demonstrated to be an effective low cost and accessible tool for the measurement of bubble and coalescence event counts, gas and liquid slug velocities, bubble length and diameter, gas volume fraction, and to indicate steady state ascent.