We revisit a class of integer optimal control problems for which a
trust-region method has been proposed and analyzed in arXiv:2106.13453v3
[math.OC]. While the algorithm proposed in arXiv:2106.13453v3 [math.OC]
successfully solves the class of optimization problems under consideration, its
convergence analysis requires restrictive regularity assumptions. There are
many examples of integer optimal control problems involving partial
differential equations where these regularity assumptions are not satisfied. In
this article we provide a way to bypass the restrictive regularity assumptions
by introducing an additional partial regularization of the control inputs by
means of mollification and proving a $\Gamma$-convergence-type result when the
support parameter of the mollification is driven to zero. We highlight the
applicability of this theory in the case of fluid flows through deformable
porous media equations that arise in biomechanics. We show that the regularity
assumptions are violated in the case of poro-visco-elastic systems, and thus
one needs to use the regularization of the control input introduced in this
article. Associated numerical results show that while the homotopy can help to
find better objective values and points of lower instationarity, the practical
performance of the algorithm without the input regularization may be on par
with the homotopy.