Shock-driven gas curtain: fractal dimension evolution in transition to turbulence

We present estimates of the Hausdorff fractal dimension of a planar section of the interfaces on the sides of a thin curtain of heavy gas (SF6) embedd ed in air and accelerated with a planar shock wave at Mach 1.2. As the Rich tmyer-Meshkov instability develops, eventually leading to a transition to t urbulence in the curtain, the fractal dimension of the interfaces increases from an initial value not exceeding 1.10 to a maximum value 1.36 +/- 0.07. This value is close to that experimentally measured for fully developed tu rbulence. The growth of the fractal dimension is closely related to mixing in the how It represents an important and previously unmeasured property in the transition to turbulence due to Richtmyer-Meshkov instability. (C) 199 9 Elsevier Science B.V. All rights reserved.