  A physical description of the formation and propagation of the working
surface inside the relativistic jet of the Blazar PKS 1510-089 are used to
model its gamma-ray variability light curve using FERMI-LAT data from 2008 to
2012. The physical model is based on conservation laws of mass and momentum at
the working surface as explained by Mendoza et al. (2009). The hydrodynamical
description of the working surface is parametrised by the initial velocity and
mass injection rate at the base of the jet. We show that periodic variations on
the injected velocity profiles are able to account for the observed luminosity.
With this, we are able to obtain mass ejection rates of the central engine
which are injected at the base of the jet, and oscillation frequencies of the
flow, amongst other physical parameters.
