Anomaly of spontaneous transition to instability of liquid–vapour front in a porous medium. (May 2015)

• Record Type: Journal Article
• Authors: Khan, Zafar Hayat; Pritchard, David
• Is Part Of: International journal of heat and mass transfer. Volume 84(2015:May)
• Page Start: 448
• Page End: 455
• Publication Date: 2015-05
• Subjects: Geothermal system -- Liquid–vapour front -- Spontaneous transition -- Rayleigh–Taylor instability; Heat -- Transmission -- Periodicals; Mass transfer -- Periodicals; Chaleur -- Transmission -- Périodiques; Transfert de masse -- Périodiques; Electronic journals; 621.4022
• DOI: 10.1016/j.ijheatmasstransfer.2015.01.007
• Languages: English
• ISSNs: 0017-9310

Abstract

Abstract: In this article, we have investigated the instability of the liquid–vapour front in a geothermal system with isothermal boundaries. A two–dimensional linear stability analysis of the isothermal basic state shows that the Rayleigh–Taylor mechanism is the dominant contributor to instability. A conditional expression for the critical modified Rayleigh number for different heat transport processes has been found. It has been shown that the spontaneous transition to instability is an artefact of neglecting thermal advection and the imposition of the phase change front to be equidistant from the liquid and vapour boundaries.