  This paper presents a non-intrusive framework for integrating existing
unsteady partial differential equation (PDE) solvers into a parallel-in-time
simultaneous optimization algorithm. The time-parallelization is provided by
the non-intrusive software library XBraid, which applies an iterative multigrid
reduction technique to the time domain of existing time-marching schemes for
solving unsteady PDEs. Its general user-interface has been extended for
computing adjoint sensitivities such that gradients of output quantities with
respect to design changes can be computed parallel-in-time alongside with the
primal PDE solution. In this paper, the primal and adjoint XBraid iterations
are embedded into a simultaneous optimization framework, namely the One-shot
method. In this method, design updates towards optimality are employed after
each state and adjoint update such that optimality and feasibility of the
design and the PDE solution are reached simultaneously. The time-parallel
optimization method is validated on an advection-dominated flow control problem
which shows significant speedup over a classical time-serial optimization
algorithm.
