The boundary layer on a finite flat plate

The problem of finding the flow over a finite flat plate aligned with a uniform free stream is revisited. Multigrid is used to obtain accurate numerical solutions up to a Reynolds number of 4000. Fourier boundary conditions keep the computational domain small, with no loss of accuracy. Near the trailing edge, excellent agreement with first-order triple-deck theory is found. However, previous comparisons between computations, experiments, and triple-deck theory are shown to be misleading: In fact, triple-deck theory only accounts for half the drag excess (that part not due to the first-order Blasius boundary layer) even at R = 4000. The remainder is shown to be due to, among other things, a large displacementlike effect in the boundary layer, i.e., an O(R ’ ) increase in skin friction extending over the whole plate.