In the first part, the boundary conditions for an open wind tunnel (incompressible flow) are examined with special reference to the effects of the closed entrance and exit sections. Basic conditions are that the velocity must be continuous at the entrance lip and that the velocities in the upstream and downstream closed portions must "be equal. For the two-dimensional open tunnel, interesting possibilities develop from the fact that the pressures on the two free surfaces need not be equal.nElectrical analogies that might be used for solving the flow in open wind tunnels are outlined. Two types are described - one in which electrical potential corresponds to velocity potential, and another in which electrical potential corresponds to acceleration potential. The acceleration-potential analogies are probably experimentally simpler than the velocity-potential analogies.
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