  A sensitive porosity adjoint method (SPAM) for optimizing the topology of
fluid machines has been proposed. A sensitivity function with respect to the
porosity has been developed. In the first step of the optimization process,
porous media are introduced into the flow regime according to the sensitivity
function. Then the optimized porous media are transformed to solid walls. The
turbulent flow in porous media is accounted for by a modified eddy-viscosity
based turbulence model. Its influence on the adjoint equations is nevertheless
neglected, which refers to the so called frozen turbulence assumption. A test
case of application in terms of the turbulent rough wall channel flow shows
that a considerable reduction of the objective function can be obtained by this
method. The transformation from porous media to solid walls may have important
effect on the optimization results.
