Paper presented at the 5th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 1-4 July, 2007.
In a fluid flow field where velocities are measured or
numerically calculated, the vorticity value at a point in the
field is usually estimated by approximating partial
derivatives of velocity with ratios of velocity differences
and spatial differences. Based on the fundamental
definition of rotation, this paper presents an alternate
approach to estimate vorticity, by using the instantaneous
relative angular velocity of finite line segments radiating
from the point to adjacent points in the fluid.
The number, length and placement of line segments are
varied to find their effects on predicted vorticity values in
four laminar flow fields with known vorticity. Equations
are also derived for a configuration consisting of four
independent finite line segments which has application to a
square numerical velocity mesh and to instrumentation such
as hot wire vorticity probes and vane vorticity meters. The
results presented are relevant to both experimental and
computational fluid mechanics.