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On identification of flow separation and vortices in internal periodic flows
Author(s) -
Rosenfeld Moshe
Publication year - 1995
Publication title -
international journal for numerical methods in fluids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.938
H-Index - 112
eISSN - 1097-0363
pISSN - 0271-2091
DOI - 10.1002/fld.1650210405
Subject(s) - vortex , mechanics , flow (mathematics) , flow separation , vorticity , open channel flow , internal flow , physics , external flow , streamlines, streaklines, and pathlines , tourbillon , hele shaw flow , isothermal flow , classical mechanics , turbulence
To permit simplified analysis of complex time‐dependent flows, possible relationship between the near‐wall flow, flow separation and vortices are studied numerically for a flow in a constricted two‐dimensional channel. The pulsating incoming wave‐form consists of a steady flow, followed by a half‐sinus flow superimposed on the steady component. One pair of vortices is created in each cycle, one vortex near each wall. The vortices propagate downstream in the next cycles, promoting flow separation as they move. Existing flow separation criteria were not found to be uniformly valid. A relation between the near‐wall flow and the vortical system exists only during the steady incoming flow phase of the cycle. It seems that local criteria of flow separation cannot be found for complex internal pulsating flow fields. However, the vorticity field can be utilized, even in complex time‐periodic flows, for identifying vortices that have been formed by the roll‐up of shear layers.