  We present a code, VeDyn, for modelling envelopes and atmospheres of A to F
stars focusing on accurate treatment of convective processes. VeDyn implements
the highly sophisticated convection model of Canuto and Dubovikov (1998) but is
fast and handy enough to be used in practical astrophysical applications. We
developed the HME envelope solver for this convection model furtheron to
consistently model the envelope together with the stellar atmosphere. The
synthesis code SynthV was extended to account for the resulting velocity
structure. Finally, we tested our approach on atomic line bisectors. It is
shown that our synthetic line bisectors of HD108642 bend towards the blue and
are of a magnitude comparable to the observed ones. Even though this approach
of modelling convection requires the solution of a coupled system of nonlinear
differential equations, it is fast enough to be applicable to many of the
investigation techniques relying on model atmospheres.
