# Alejandro Selkirk Island Von Karman vortex street

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 May 31, 2012, 18:53 Alejandro Selkirk Island Von Karman vortex street #1 New Member   Jean Dupont Join Date: May 2012 Posts: 1 Rep Power: 0 Dear all, I'm trying to determine the velocity of the coulds that made a Von Karman vortex street near Juan Fernandez Islands: http://earthobservatory.nasa.gov/IOTD/view.php?id=625 A Von Karman vortex street occures for: Re = 90 Alejandro Selkirk Island diameter is: D = 1500 meters The air kinematic viscosity is: nu_air = 15.6E-06 meters**2 / second The relation is: Re = Velociy_clouds * D_vortex / nu_air So: Velocity_clouds = Re * nu_air / D_vortex = 2.8E-07 meters / second = 1 meter / 12 days Cloud velocity is 1 meter / 12 days, really?

 May 31, 2012, 22:09 #2 Senior Member   Join Date: Jul 2009 Posts: 310 Rep Power: 15 Why pick a Reynolds number of 90? A vortex street can exist for a wide range of Reynolds numbers.

 Tags reynolds number, vortex street