  We report on our attempts to achieve a nearly steady-state gas flow in
hydrodynamical simulations of doubly barred galaxies. After exploring the
parameter space, we construct two models, for which we evaluate the photometric
and the kinematic integrals, present in the Tremaine-Weinberg method, in search
of observational signatures of two rotating patterns. We show that such
signatures are often present, but a direct fit to data points is likely to
return incorrect pattern speeds. However, for a particular distribution of the
tracer, presented here, the values of the pattern speeds can be retrieved
reliably even with the direct fit.
