Mechanical Engineering - Research Publications

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1995 - 1998 3
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Start date: 1990 × End date: 1999 × Author: JONES, MALCOLM ×

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    New evolution equations for turbulent boundary layers in arbitrary pressure gradients
    Perry, A. E. ; Marusic, I. ; Jones, M. B. ( 1997)
    A new approach at looking at the classic closure problem for turbulent boundary layers is presented. This involves using the well known mean-flow scaling laws such as Prandtl's law of the wall and Coles' law of the wake together with the mean momentum integral and differential equations. The important parameters governing the flow in the general non-equilibrium case are identified and are used to formulate the closure hypothesis. Once the mean flow field has been determined, relevant turbulence quantities can be computed using a coherent structure eddy model based on the attached eddy hypothesis.
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    The effect of aspect ratio and divergence on the turbulence structure of boundary layers
    Jones, M. B. ; Marusic, I. ; Perry, A. E. ( 1995)
    The effect of the aspect ratio of a turbulent boundary layer on the mean flow, broadband turbulence intensities and Reynolds shear stress has been studied. The aspect ratio (AR) is defined as the boundary layer thickness divided by the boundary layer width, i.e. the effective wind tunnel width. Measurements have been taken in a nominally zero pressure gradient layer at a single station for three different aspect ratio settings, AR=1/4, AR=1/7, and AR=1/13. The measurements show that the turbulent quantities were unaffected when the aspect ratio was increased from AR=1/13 to AR=1/7. However at AR=1/4 there appears to be a slight increase in the broadband turbulence intensities and Reynolds shear stress.
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    New evolution equations for turbulent boundary layers in arbitrary pressure gradients
    Perry, A. E. ; Marusic, I. ; Jones, M. B. (Indian Academy of Sciences, 1998)
    A new approach to the classical closure problem for turbulent boundary layers is presented. This involves using the well-known mean-flow scaling laws such as Prandtl's law of the wall and the law of the wake of Coles together with the mean continuity and the mean momentum differential and integral equations. The important parameters governing the flow in the general non-equilibrium case are identified and are used for establishing a framework for closure. Initially, closure is done here empirically from the data but the framework is most suitable for applying the attached eddy hypothesis in future work. How this might be done is indicated here.