  We predict the structure and dynamics of disc galaxies using galaxy evolution
models within a hierarchical formation scenario The halo mass aggregation
histories, for a Lambda CDM model, were generated and used to calculate the
virialization of dark matter (DM) haloes. A diversity of halo density profiles
were obtained, the most typical one being close to the NFW profile. We modeled
the formation of discs in centrifugal equilibrium within the evolving DM haloes
using gas accretion rates proportional to the halo mass aggregation rates, and
assuming detailed angular momentum conservation. We calculated the
gravitational interactions between halo and disc, and the hydrodynamics, star
formation, and evolution of the galaxy discs. We found that the slope and
zero-point of the infrared Tully-Fisher relations (TFR) may be explained as a
direct consequence of the cosmological initial conditions. This relation is
almost independent of the assumed disc mass fraction. The rms scatter of the
TFR originates mainly from the scatter in the DM halo structure and, to a minor
extension, from the dispersion of the primordial spin parameter. The scatter
obtained does not disagree with the observational estimates. Our models allow
us to understand why the residuals of the TFR do not correlate significantly
with disc size or surface brightness (SB), and why low and high SB galaxies
have the same TFR. The correlations between gas fraction and SB, and between
scale length and V_max agree with those observed. The discs present nearly
exponential SB distributions. The shape of the rotation curves changes with the
SB and is nearly flat for most cases. The rotation curve decompositions show a
dominance of DM down to very small radii. The introduction of shallow cores in
the DM halo attenuates this difficulty.
