Because aerodynamic interferences between an airfoil model and wind-tunnel walls cannot be avoided, the concept of an adaptive-wall to reduce the previouse interferences has been condsidered. This paper presents numerical simulations of pressure control at two-dimensional ventilated straight walls. Numerical wind-tunnel inner flow past airfoil and outer flow are calculated simultaneously and independently on basis Euler equations using a finite difference method in Cartesian grid. The concept of adaptive wall requires that the inner flow match the outer flow at the ventilated walls. This requirement is satisfied by matching of flow direction and pressure at both sides of the ventilated straight wall.
Numerical adaptive wall wind-tunnel tests of NACA0012 airfoil are performed to demonstrate potentialities of the adaptive-wall control. Several calculated results of airfoil abilities in the numerical wind tunnel are compared with experimental and another calculated results.

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The flow field produced by a vortex ring at Re=2600 impinging on a flat plate was examined in detail using a smoke visualization method. The longitudinal vortex structure with a finger-like configuration was found which plays a crucial role in forming azimuthal coherent structures with a cross section resembling that of an orange; the structures promote the flow field into turbulent state. The generating and developing process of the longitudinal vortex was discussed, and the topological aspects were inferred by integrating information obtained through various local visualizations.

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