2012/04/05 by Lennon Ó Náraigh, Naraigh, Lennon O., Peter Spelt +3
Earth and Planetary Sciences · Engineering · #FOS: Physical sciences #Fluid Dynamics (physics.flu-dyn) #Fluid Dynamics and Turbulent Flows #Meteorological Phenomena and Simulations #Ocean Waves and Remote Sensing
paper · pdf · doi:10.48550/arxiv.1204.1263
openalex publication_date 2012/04/05 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We study two-phase stratified flow where the bottom layer is a thin laminar\nliquid and the upper layer is a fully-developed gas flow. The gas flow can be\nlaminar or turbulent. To determine the boundary between convective and absolute\ninstability, we use Orr--Sommerfeld stability theory, and a combination of\nlinear modal analysis and ray analysis. For turbulent gas flow, and for the\ndensity ratio r=1000, we find large regions of parameter space that produce\nabsolute instability. These parameter regimes involve viscosity ratios of\ndirect relevance to oil/gas flows. If, instead, the gas layer is laminar,\nabsolute instability persists for the density ratio r=1000, although the\nconvective/absolute stability boundary occurs at a viscosity ratio that is an\norder of magnitude smaller than in the turbulent case. Two further unstable\ntemporal modes exist in both the laminar and the turbulent cases, one of which\ncan exclude absolute instability. We compare our results with an\nexperimentally-determined flow-regime map, and discuss the potential\napplication of the present method to non-linear analyses.\n