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Viscous heating effects in fluids with temperature-dependent viscosity: triggering of secondary flows
Language
English
Obiettivo Specifico
4V. Dinamica dei processi pre-eruttivi
5V. Dinamica dei processi eruttivi e post-eruttivi
Status
Published
JCR Journal
JCR Journal
Title of the book
Issue/vol(year)
/540 (2005)
Pages (printed)
21-38
Issued date
2005
Abstract
Viscous heating can play an important role in the dynamics of fluids with a strongly temperature-dependent viscosity because of the coupling between the energy and momentum equations. The heat generated by viscous friction produces a local increase in temperature near the tube walls with a consequent decrease of the viscosity and a strong stratification in the viscosity profile which can trigger instabilities and a transition to secondary flows.
In this paper we present two separate theoretical models: a linear stability analysis and a direct numerical simulation (DNS) of a plane channel flow. In particular DNS shows that, in certain regimes, viscous heating can trigger and sustain a particular class of secondary rotational flows which appear organized into coherent structures similar to roller vortices. This phenomenon can play a very important role in the dynamics of magma flows and, to our knowledge, it is the first time that it has been investigated by a direct numerical simulation.
In this paper we present two separate theoretical models: a linear stability analysis and a direct numerical simulation (DNS) of a plane channel flow. In particular DNS shows that, in certain regimes, viscous heating can trigger and sustain a particular class of secondary rotational flows which appear organized into coherent structures similar to roller vortices. This phenomenon can play a very important role in the dynamics of magma flows and, to our knowledge, it is the first time that it has been investigated by a direct numerical simulation.
Type
article
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