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NUMERICAL STUDY OF THE BLOCKAGE EFFECTS ON VISCOUS FLOW PAST A CIRCULAR CYLINDER
Author(s) -
ANAGNOSTOPOULOS P,
ILIADIS G,
RICHARDSON S
Publication year - 1996
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/(sici)1097-0363(19960615)22:11<1061::aid-fld393>3.0.co;2-q
Subject(s) - strouhal number , potential flow around a circular cylinder , mechanics , cylinder , stream function , conservative vector field , vortex , vortex shedding , potential flow , flow (mathematics) , computational fluid dynamics , boundary value problem , mathematics , wake , geometry , reynolds number , physics , vorticity , mathematical analysis , open channel flow , compressibility , turbulence
In various numerical solutions of flow around bluff bodies the unbounded physical domain is replaced by a restricted computational one whose extent depends on the size of the computational grid network. The truncation of the solution domain in the cross‐flow direction reduces the computer time required for the solution, but introduces numerical blockage effects which influence considerably the values of the various flow parameters. In the present paper the finite element solution of steady and unsteady flow around a circular cylinder at Re =106 is presented for blockage ratios of 0·05, 0·15 and 0·25. A boundary condition was tested for which the streamfunction values at the outer boundaries were those of the irrotational solution around a circular cylinder. The size of the standing vortices decreases with the blockage ratio when the flow is steady, while the spacing of the vortices decreases in both directions with increasing blockage ratio when the wake becomes unsteady. The hydrodynamic forces on the cylinder and the Strouhal number are magnified as the blockage ratio increases. The application of the streamfunction values derived from the irrotational solution at the outer boundaries reduced blockage effects only at high blockage ratio.