On the symmetry of the age field of a passive tracer released into a onedimensional fluid flow by a pointsource
Deleersnijder, E.; Delhez, E.J.M.; Crucifix, M.; Beckers, J.M. (2001). On the symmetry of the age field of a passive tracer released into a onedimensional fluid flow by a pointsource. Bull. Soc. r. Sci. Liège 70(1): 521
In: Bulletin de la Société Royale des Sciences de Liège. Société Royale des Sciences de Liège: Liège. ISSN 00379565; eISSN 17835720, more
 
Keywords 
Age Motion > Fluid motion > Fluid flow Symmetry Symmetry Tracers Transport processes > Advection Marine/Coastal 
Authors   Top 
 Deleersnijder, E., more
 Delhez, E.J.M., more
 Crucifix, M., more
 Beckers, J.M., more



Abstract 
Tracer is released from a pointsource into an incompressible, onedimensional fluid flow, with constant velocity and diffusivity. The age of a tracer parcel, which is defined as the time elapsed since leaving the source, may be evaluated as the ratio of the age concentration to the tracer concentration. The latter are governed by two partial differential equations. Timedependent analytical solutions are derived, which show that the age is symmetric with respect to the source. This is astonishing, since it could have been expected that the age would reflect somehow the strong asymmetry of the tracer concentration, which tends to be much larger on the downstream side of the source than on the upstream side. Some finitedifference counterparts of this problem are seen to lead to age fields which, in their steadystate limit, are also symmetric with respect to the source. This is believed to be helpful to interpret the results of numerical models of complex fluid flows in which the age is introduced as a diagnostic variable. 
