On the flow around a hydrofoil close to a permeable wall

In the pulp and paper-making industry, pressurized screens are used to purify the pulp and to protect the wires on the paper machine. The appertures (slots or holes) on the screen are kept clean from fibers and shives by foils rotating close to the permeable surface. The leading-order theory of a ``wing in extreme ground effect'' has been modified to take into account the permeability of the screen-plate. Methods for predicting flow separation and for modifying the potential-flow solution due to the same are discussed, and numerical simulations are presented for comparison.