  Many of the most intriguing features, including spirals and cavities, in the
current disc observations are found in binary systems like GG Tau, HD 142527 or
HD 100453. Such features are evidence of the dynamic interaction between binary
stars and the viscous disc. Understanding these dynamic interactions and how
they result in the structure and growth of asymmetric circumbinary discs is a
difficult problem, for which there is no complete analytical solution, that
predicts the shape of the observed disc accurately. We use numeric simulation
to evolve circumbinary discs with varying disc viscosities and investigate the
size and shape of the inner cavities in such protoplanetary discs. We have
simulated over 140 locally isothermal 2D grid-based disc models for > 3e4
binary orbits each and mapped out the parameter space relevant for
protoplanetary discs. With this, it becomes possible to create parametrised
profiles for individual discs to compare to observation and find limits to
their binary eccentricity or internal viscosity from the simulation data. In
the long-term simulations larger cavity sizes than previously considered are
possible within the parameter space (< 6 binary separations). As an example, we
find that the eccentricity of the disc around HD 142527 suggests the impact of
the binary dynamics on the disc. However, even considering the larger cavity
sizes, the large size of the cavity in HD 142527 remains unexplained by the
simulations considering the most recent orbital constraints.
