Abstract
The isolated singular points (nodes, saddles) of a continuous vector field (e.g., velocity, shear stress, pressure gradient, vorticity, etc.) that are overlaid on a given surface must be compatible with the Euler characteristic of that surface, Xsurface. All surfaces can be fashioned from a sphere plus handles plus holes, and Xsurface=2−Σholes−2Σhandles=Σnodes−Σsaddles. This establishes an a priori constraint for the nodes and saddles that can be tested against the observed vector field to determine whether the experimental (or computational) observations are compatible with the known constraint. Numerous examples, including a clarification of, and a correction to, published results are given.
Similar content being viewed by others
Notes
These references were kindly supplied by a reviewer.
A formal definition of a sphere is provided in the Appendix.
References
Bredon GE (1993) Topology and geometry. Springer, Berlin Heidelberg New York
Davis HT (1962) Introduction to nonlinear differential and integral equations. Dover, New York, pp 351–355
Hunt JCR, Abell CJ, Peterka JA, Woo H (1978) Kinematical studies of the flows around free or surface-mounted obstacles: applying topology to flow visualization. J Fluid Mech 86:179–200
Hurewicz W (1958) Lectures on ordinary differential equations. Wiley, New York, pp 111–113
Koster JN, Müller U (1982) Free convection invertical gaps. J Fluid Mech 125:429
Koster JN, Müller U (1984) Oscillatory convection in vertical slots. J Fluid Mech 139:363
Lighthill MJ (1963) Attachment and separation in three-dimensional flow. In: Rosenhead L (ed) Laminar boundary layers, vol 2.6. Oxford University Press, Oxford, pp 72–82
Martinuzzi R, Tropea C (1993) The flow around surface-mounted, prismatic obstacles placed in a fully developed channel flow. J Fluid Eng 115(1):85–92
Milnor JW (1997) Topology from the differential viewpoint. Based on notes by Weaver DW. Princeton University Press, New Jersey
Perry AE, Chong MS (1987) A description of eddying motions and flow patterns using critical-point concepts. Annu Rev Fluid Mech 19:125–155
Perry AE, Chong MS (1994) Topology of flow patterns in vortex motions and turbulence. Appl Sci Res 53:357–374
Ruderich R, Fernholz HH (1986) An experimental investigation of a turbulent shear flow with separation, reverse flow, and reattachment. J Fluid Mech 163:283–322
Tobak M, Peake DJ (1979) Topology of two-dimensional and three-dimensional separated flows. In: Proceedings of the AIAA 12th fluid and plasma dynamics conference, Williamsburg, Virginia, July 1979. AIAA paper 79–1480
Tobak M, Peake DJ (1982) Topology of three-dimensional separated flows. Annu Rev Fluid Mech 14:61–85
Zimmermann G, Ehrhard P, Mueller U (1986) Stationäre und Instationäre Konvektion in einer quadratischen Hele-Shaw Zelle, Primärbericht IRB-Nr 507/86 (Mai)
Acknowledgements
The author’s original experience with the motivating elements for this exposition were gained as an Alexander von Humboldt Fellow at the University of Karlsruhe. Professor W. Rodi served as the research host for this experience. Grateful appreciation is expressed to the AvH and Professor Rodi. MSU mathematics colleagues, Professors R. Miller and J. McCarthy, have provided substantial guidance and instruction for the topological elements presented herein. Useful discussions and clarifications were also gained from a 1995 interaction with Professors A.E. Perry and M.S. Chong at the University of Melbourne. Expert assistance with the preparation of the figures has been provided by M. Dusel and A. Butki.
Author information
Authors and Affiliations
Corresponding author
Appendix
Appendix
The following definition was provided to the author by Professor J.D. McCarthy. It is repeated here for mathematical completeness in relation to the centrally important understanding of a sphere in this communication.
An appropriate definition, in the context of the present communication, which is focused on three-dimensional Euclidean space, R3, can be expressed as follows. A sphere can be understood as that of a smooth two-dimensional submanifold S of R3 diffeomorphic to the standard two-dimensional sphere S2 in R3 (i.e., the set of all points in R3 at a distance of 1 from the origin (0, 0, 0) of R3):
-
1.
A subset S of R3
-
2.
With a smoothly varying two-dimensional tangent space at each point p of S
-
3.
Admitting a smooth map F: S2→S with a smooth inverse map G: S→S2
Rights and permissions
About this article
Cite this article
Foss, J.F. Surface selections and topological constraint evaluations for flow field analyses. Exp Fluids 37, 883–898 (2004). https://doi.org/10.1007/s00348-004-0877-0
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00348-004-0877-0