3. Karman Vortex Street
Repeated shedding of swirling vortices
Caused by unsteady separation of flow over a bluff
body
Result of form drag and not viscous drag
Some jargon: wake, vortex, recirculation, bluff body
5. What exactly happens
The wake of the bluff body may become unstable due
to a very small perturbation in the flow
Once asymmetry is induced its magnified several fold
and one vortex is shed
Causes asymmetric pressure distribution and the
pattern repeats
Phenomenon normally observed at low Reynolds
Numbers (90+)
8. Sample Calculation
Flow Parameters
V d Ro Mu Re
0.1 0.05 0.9885 2.28E-05 2.17E+02
Vortex Shedding Time Scale
f T
3.60E-01 2.78E+00
Calculations for Total Heat Transfer Rate
Nu 8.564286454
Pr 0.7
Re 2.17E+02
k 0.03
h 5.138571872
dT 123
A 0.157079633
Q 99.28129281
CFD Q 91.9
error % 7.434726727