INVESTIGATION OF THE BOUNDARY CONDITION AT A PERFORATED WALL
Abstract
The problem considered is that of findings a potential which will yield a constant horizontal velocity in a slot in a solid wall but no vertical velocity outside the slot. The pressure over the slot width is assumed to be constant. The problem is transformed to that of the perturbation flow field generated by a flat plate moving downward with a constant velocity. The potential of the flat plate is obtained by applying the Joukowski transformation to the flow about a cylinder. A consideration of the boundary conditions indicates that the solutions must be limited to those having a stagnation point at one edge of the slot for an appropriate solution to be obtained for the velocity distribution about the slot. A method described by Grammel (Die Hydrodynamischen Grundlagen des Fluges, Friedrich Vieweg, Braunschweig, 1917) is used to obtain the velocities produced by a wall considered as containing an infinite number of transverse slots uniformily spaced along an axis. The theoretical analysis was confirmed by experiments with a low-speed wind tunnel. As an additional experiment the influence of the initial boundary layer was determined by tests on perforated metal inserts of 1- to 5-in. lengths. The results indicated that the boundary condition for a perforated wall is linear. The Reynolds number, which varied over a large range, does not affect the linearity.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1953
- Accession Number
- AD0014022
Entities
People
- Paul F. Maeder
Organizations
- Brown University