|Some properties of generalized age-distribution equations in fluid dynamics|
Beckers, J.-M.; Delhez, E.; Deleersnijder, E. (2001). Some properties of generalized age-distribution equations in fluid dynamics. SIAM J. Appl. Math. 61(5): 1526-1544
In: SIAM Journal on Applied Mathematics. Society for Industrial and Applied Mathematics (SIAM): Philadelphia, Pa.. ISSN 0036-1399, more
Advection; Age; Diffusion; Equations; Fluid dynamics; Marine
The concept of age in fluid dynamics is analyzed in the case of a tracer advection- diffusion equation. From the general solution in a uniform velocity field, it is shown that unexpected symmetry properties arise for the age field. In particular, for a point release, the age field is isotropic, regardless of the direction of the flow and the value of the diffusion coefficient. The analysis is then extended to situations with time-varying currents, where the symmetry can be broken under some circumstances. Finally, we show a method by which a time-dependent problem can be used to assess a stationary concentration distribution function, providing details about the propagation of younger and older material at a given location.