Mechanical Engineering - Research Publications
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ItemApplication of the wavelet transform in turbulence( 1997)Traditionally, Fourier transforms have been used to elicit the scale-based behaviour of the turbulent motion and one speaks synonymously of its wavenumber components with scales (large scales are associated with small wavenumbers and vice-versa). Although, this approach is theoretically correct, many workers have questioned its appropriateness on the grounds that a Fourier mode represents a wave like disturbance which is global in the physical domain, whereas an eddy is a disturbance with finite spatial extent. Consequently, a more appropriate scheme should involve a local decomposition of the velocity field which is more reminiscent of eddy like phenomena. In this paper we have explored the feasibility of the wavelet transform as an analyzing tool in deducing the turbulence spectrum.
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ItemApplication of the attached eddy hypothesis for the evolution of turbulent boundary layers( 1997)The wall-wake attached eddy model of Perry & Marusic [1] is incorporated in a new approach to the classic closure problem for turbulent boundary layers recently proposed by Perry, Marusic & Jones [2]. 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.
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ItemNew evolution equations for turbulent boundary layers in arbitrary pressure gradients( 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.