  We present one-dimensional hydrodynamical simulations including radiative
losses, of internal shocks in the outflows from classical novae, to explore the
role of shocks in powering multi-wavelength emission from radio to gamma-ray
wavelengths. Observations support a picture in which the initial phases of some
novae generate a slow, equatorially-focused outflow (directly from the outer
Lagrange point, or from a circumbinary disk), which then transitions to, or is
overtaken by, a faster more isotropic outflow from the white dwarf which
collides and shocks the slower flow, powering gamma-ray and optical emission
through reprocessing by the ejecta. However, the common occurence of multiple
peaks in nova light curves suggests that the outflow's acceleration need not be
monotonic, but instead can involve successive transitions between "fast" and
"slow" modes. Such a time-fluctuating outflow velocity naturally can reproduce
several observed properties of nova, such as correlated gamma-ray and optical
flares, expansion of the photosphere coincident with (though lagging slightly)
the peak flare luminosity, and complex time-evolution of spectral lines
(including accelerating, decelerating, and merging velocity components). While
the shocks are still deeply embedded during the gamma-ray emission, the onset
of $\sim$ keV X-ray and $\sim 10$ GHz radio synchrotron emission is typically
delayed until the forward shock of the outermost monolithic shell (created by
merger of multiple internal shock-generated shells) reaches a sufficiently low
column through the dense external medium generated by the earliest phase of the
outburst.
