Unsteady Three-Dimensional Separated Flows Around a Sphere - Analysis of Vortex Chain Formation

  • U. Dallmann
  • H. Gebing
  • H. Vollmers
Conference paper
Part of the International Union of Theoretical and Applied Mechanics book series (IUTAM)

Abstract

The near-wake vortex formation process behind blunt bodies is still unclear. While experiments often provide high-resolution of the far-wake vortex flow or the wall-flow (oil-flow visualization) it is still difficult to get insight into the unsteady, threedimenisonal near-wake flow. Therefore, the aim of our analysis of a low Mach number (Ma = 0,4) numerical flow simulation around a sphere is to shed some light onto the near-wake flow region. Different types of vortices, vortex chains and vortex sheddings appear in experiments [1] for increasing Reynolds numbers. For the time being, we are limited to a 71 × 71 × 71 mesh with approximately 25 grid points for Re = 400 in wall-normal direction within the boundary layer near the point of flow separation. Since the sequence of topological changes of the various quantities defining a flow field in parameter space is not necessarily dependent on the numerical resolution (although the quantitative differences for some fixed parameters may be considerable) we can hope to identify generic features of structural flow changes despite of the numerical resolution limitations given. A review of our earlier results is given in [2].

Keywords

Vortex Vorticity Smoke Convolution 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. [1]
    Sakamoto, H., Haniu, H., A Study on vortex shedding from spheres in a uniform flow. Journal of Fluids Engineering, Vol. 112 (1990) 386–392.ADSCrossRefGoogle Scholar
  2. [2]
    Dallmann, U., Kordulla, W., Vollmers, H., Schulte-Werning, B., Analysis of the changing topological structures of three-dimensional separated flows DLR-IB 221–92 Al2 and in: ‘Physics of Separated Flows’ K. Gersten (Ed.), Vieweg-Series ‘Notes on Numerical Fluid Mechanics’, 1992 (to appear).Google Scholar
  3. [3]
    Schulte-Werning, B., Numerische Simulation and topologische Analyse der abgelösten Strömung an einer Kugel. DLR-FB 90–43, 1990 (PhD-thesis Munich Technical University, 1990 ).Google Scholar
  4. [4]
    Shirayama. S., Flow past a sphere: topological transition of the vorticity field. AIAA Journal, Vol. 30, No. 2 (1992) 349–358.ADSCrossRefMATHGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 1993

Authors and Affiliations

  • U. Dallmann
    • 1
  • H. Gebing
    • 1
  • H. Vollmers
    • 1
  1. 1.DLR — Institute of Theoretical Fluid MechanicsGöttingenGermany

Personalised recommendations