Cent. Eur. J. Eng. • 1(4) • 2011 • 390-400 DOI: 10.2478/s13531-011-0037-2 Vortex Patch with Wall Interaction as New Benchmark Test Ziemowit Milosz Malecha 12∗ 1 Integrated Applied Mathematics Program, University of New Hampshire, Durham, USA 2 Faculty of Mechanical and Power Engineering, Wroclaw University of Technology, Wroclaw, Poland In this paper, a new computational benchmark test for fluid dynamics is presented. The new benchmark is based on the interaction of a single vortex structure (vortex patch) with a wall. It will be shown that it is possible to distinguish two critical or threshold values of the Reynolds number in the considered flow. The increase of the Reynolds number causes the appearance of the vortex bubble in the near-wall region first, and then next, the eruption of the boundary layer phenomenon. Further increase of the Reynolds number causes the flow to be more complex. The eruption phenomenon becomes more intense and also shows its regenerative nature. Benchmark test • Boundary layer • Rruption • Vortex-in-cell method © Versita sp. z o.o. 1. Introduction Vorticity is fundamental in the mechanics of fluids. Each real flow has a non-zero vorticity. A great number of phe- nomena in hydrodynamics is analyzed from the perspective of vorticity dynamics. Many flows produce characteristic vortices, of which their structure and behavior can give us much important and interesting information about the con- sidered flow. Moreover, these vortex structures appear in very specific circumstances and act in very specific ways, depending on the Reynolds number. A well known exam- ple can be found in the flow around the cylinder, or in the flow in the rectangular box with one moving wall (cavity flow). The frequency of the vortices which have been shed ∗ E-mail: ziemowit.malecha@pwr.wroc.pl from the cylinder, and the appearance and shape of the corner vortices in the cavity flow, change very specifically with the Reynolds number. They often serve as benchmark tests for new computational algorithms or experimental se- tups [1]. In an incompressible flow, vorticity can be generated only on the rigid wall. Vortex production on the wall is forced by the fluid viscosity (no-slip condition). The production of the vorticity on the wall can be interpreted as neces- sary for the maintenance of the no-slip condition [2, 3]. Introduction of the vorticity from the wall can take place through short range diffusion, as in laminar flow, or can happen abruptly through vorticity eruption from the wall layer [4, 5]. In some authors’ recent works [4, 6], the numerical inves- tigation of the boundary layer eruption phenomenon was presented. The research was mainly focused on the mu- tual interaction of the single vortex structure with the plain