  We study numerically a two-component A-B spreading model (SMK model) for
concave and convex radial growth of 2d-geometries. The seed is chosen to be an
occupied circle line, and growth spreads inside the circle (concave geometry)
or outside the circle (convex geometry). On the basis of generalised
diffusion-annihilation equation for domain evolution, we derive the mean field
relations describing quite well the results of numerical investigations. We
conclude that the intrinsic universality of the SMK does not depend on the
geometry and the dependence of criticality versus the curvature observed in
numerical experiments is only an apparent effect. We discuss the dependence of
the apparent critical exponent $\chi_{a}$ upon the spreading geometry and
initial conditions.
