  Mildly relativistic, oblique shocks are frequently invoked as possible sites
of relativistic particle acceleration and production of strongly variable,
polarized multi-wavelength emission from relativistic jet sources such as
blazars, via diffusive shock acceleration (DSA). In recent work, we had
self-consistently coupled DSA and radiation transfer simulations in blazar
jets. These one-zone models determined that the observed spectral energy
distributions (SEDs) of blazars strongly constrain the nature of the
hydromagnetic turbulence responsible for pitch-angle scattering. In this paper,
we expand our previous work by including full time dependence and treating two
emission zones, one being the site of acceleration. This modeling is applied to
a multiwavelength flare of the flat spectrum radio quasar 3C~279, fitting
snap-shot SEDs and light curves. We predict spectral hysteresis patterns in
various energy bands as well as cross-band time lags with optical and GeV
gamma-rays as well as radio and X-rays tracing each other closely with zero
time lag, but radio and X-rays lagging behind the optical and gamma-ray
variability by several hours.
