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Browsing by Author "Marusic, Ivan"

Now showing 1 - 3 of 3
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    Flow Visualization Using Natural Textures
    (2005-04-15) Urness, Timothy Matthew; Interrante, Victoria; Longmire, Ellen; Marusic, Ivan
    The use of natural textures provides a richly diverse set of possibilities for the visualization of flow data. In this paper, we present methods that utilize the qualities and attributes of natural textures to visualize multiple scalar distributions and multiple vector fields obtained across a 2D domain in a turbulent boundary layer flow. First, we illustrate how different attributes of textures can represent scalar quantities along streamlines. We then present a technique that allows for the perception of two separate vector fields within the same image by utilizing different textures. Finally, we illustrate how textures have the ability to indicate specific regions of interest within flow images.
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    On the mixing length eddies and logarithmic mean velocity profile in wall turbulence
    (Cambridge University Press, 2020-01-21) Heisel, Michael; de Silva, Charitha M; Hutchins, Nicholas; Marusic, Ivan; Guala, Michele
    Since the introduction of the logarithmic law of the wall more than 80 years ago, the equation for the mean velocity profile in turbulent boundary layers has been widely applied to model near-surface processes and parameterize surface drag. Yet the hypothetical turbulent eddies proposed in the original logarithmic law derivation and mixing length theory of Prandtl have never been conclusively linked to physical features in the flow. Here, we present evidence that suggests these eddies correspond to regions of coherent streamwise momentum known as uniform momentum zones (UMZs). The arrangement of UMZs results in a step-like shape for the instantaneous velocity profile, and the smooth mean profile results from the average UMZ properties, which are shown to scale with the friction velocity and wall-normal distance in the logarithmic region. These findings are confirmed across a wide range of Reynolds number and surface roughness conditions from the laboratory scale to the atmospheric surface layer.
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    Strategies for the Visualization of Multiple Co-located Vector Fields
    (2005-09-22) Urness, Timothy Matthew; Interrante, Victoria; Longmire, Ellen; Marusic, Ivan; O'Neill, Sean; Jones, Thomas W.
    Fluids research often involves developing theories about the complex relationships between multiple scalar and vector quantities. We discuss strategies for effectively visualizing co-located vector fields, enabling the key physical structures of one vector field to be clearly understood within the context of a related vector field. We describe the range of effects that can be obtained by combining several existing flow visualization techniques for the purposes of analyzing multiple vector fields. Results are shown through two distinctly different scientific applications: the visualization of velocity and vorticity fields in experimentally acquired turbulent boundary layer flow data, and the visualization of velocity and magnetic fields in computational simulations of astrophysical jets.