2020-08-10T05:17:27Z
http://digital.csic.es/dspace-oai/request
oai:digital.csic.es:10261/140583
2018-05-18T10:16:17Z
com_10261_5062
com_10261_5
col_10261_5064
2016-11-23T07:28:52Z
urn:hdl:10261/140583
Continuous Time Random Walks for the Evolution of Lagrangian Velocities
Dentz, Marco
Kang, Peter K.
Comolli, Alessandro
Le Borgne, T.
Lester, Daniel R.
European Research Council
CTRW
Lagrangian velocities
We develop a continuous time random walk (CTRW) approach for the evolution of Lagrangian
velocities in steady heterogeneous flows based on a stochastic relaxation process for the streamwise
particle velocities. This approach describes persistence of velocities over a characteristic spatial
scale, unlike classical random walk methods, which model persistence over a characteristic time
scale. We first establish the relation between Eulerian and Lagrangian velocities for both equidistant
and isochrone sampling along streamlines, under transient and stationary conditions. Based on
this, we develop a space continuous CTRW approach for the spatial and temporal dynamics of
Lagrangian velocities. While classical CTRW formulations have non-stationary Lagrangian velocity
statistics, the proposed approach quantifies the evolution of the Lagrangian velocity statistics under
both stationary and non-stationary conditions. We provide explicit expressions for the Lagrangian
velocity statistics, and determine the behaviors of the mean particle velocity, velocity covariance and
particle dispersion. We find strong Lagrangian correlation and anomalous dispersion for velocity
distributions which are tailed toward low velocities as well as marked differences depending on
the initial conditions. The developed CTRW approach predicts the Lagrangian particle dynamics
from an arbitrary initial condition based on the Eulerian velocity distribution and a characteristic
correlation scale.
2016-11-23T07:28:52Z
2016-11-23T07:28:52Z
2016
artículo
Physical Review Fluids
http://hdl.handle.net/10261/140583
http://dx.doi.org/10.13039/501100000781
eng
Postprint
Sí
info:eu-repo/grantAgreement/EC/FP7/617511
openAccess
American Physical Society