Mechanical Engineering - Research Publications

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1997 - 1998 3
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Start date: 1997 × End date: 1999 × Type: Journal (Paginated) ×

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    Similarity law for the streamwise turbulence intensity in zero-pressure-gradient turbulent boundary layers
    Marusic, I. ; Uddin, A. K. M. ; Perry, A. E. ( 1997)
    A similarity relationship is proposed to describe the streamwise broadband-turbulence intensity in a zero-pressure-gradient boundary layer. The formulation is applicable to the entire region of the flow beyond the viscous buffer zone and is based on the attached eddy hypothesis, the Reynolds-number-similarity hypothesis and the assumed existence of Kolmogorov eddies with a universal inertial subrange. Experimental data of the authors and those from various published works covering a large Reynolds number range are investigated in light of this formulation.
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    On the validity of Taylor's hypothesis in wall turbulence
    Uddin, A. K. Mesbah ; Perry, A. E. ; MARUSIC, IVAN ( 1997)
    The validity of Taylor’s hypothesis of frozen turbulence has been the issue of much debate, especially when applied to flows with strong shear and high turbulence intensities. In the past, Taylor’s hypothesis was used by various researchers for the quantitative interpretation of the structure angle of the eddies on the basis of double-velocity correlations (eg. Alving et al. [1]) or velocity-wall pressure or velocity-wall shear stress correlations (e.g. Brown & Thomas [2] , Rajagopalan & Antonia [6]. In light of the ambiguity associated with Taylor’s hypothesis, naturally, there are resultant uncertainties in terms of the measured structure angle. Subsequently there is a need to investigate how do these uncertainties effect the structure angle measurements and as well as to examine the validity of Taylor’s hypothesis when applied to two-point double-velocity correlation measurements in an anisotropic shear flow.
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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.