This work presents our approach for modelling the CFD challenge example of the aortic coarctation of an 8 year old child. The three-dimensional fluid domain was modeled as described in the challenge as an incompressible Newtonian fluid. A residual-based variational multiscale finite element method is used to solve the 3D fluid field. The boundaries were treated with 3-element windkessel models. The windkessel elements were tuned using an adjoint based method to fit the pressure and flowrate values reported by the challenge. A mesh refinement was performend to ensure the spatial convergence of the presented results. Finally, pressure values at
slices are reported.