Kelvin-Helmholtz instability (KHI) due to the strong vertical wind shear above and below the jet core is one of the well-known sources for CAT (e.g., Dutton and Panofsky 1970) and is related to small values of the gradient Richardson number
(Ri; a nondimensional ratio between vertical shear and stability).
The obtained results showed that the total drag coefficient increases and Nusselt number decreases with increasing Richardson number
. Also, the thermal buoyancy generates a vortex over and below the cylinder.
To interpret this phenomenon and analysis air flow effect on flame shape of pool fire, a non-dimensional number (Richardson number
) is introduced as follow.
The main dimensionless parameter here was the Richardson number
which varied from 0.1 to 10.
In addition, the Richardson number
has been also calculated to confirm the stability conditions.
The gradient Richardson number
, which is often used to quantitatively identify interfacial mixing, is introduced in Section 2.
(5), on the entrainment of ambient air on vertical air curtain upon varying the Reynolds numbers (4200-8000) and the Richardson Number
(013-0.58) which again showed that the entrainment of the ambient air was governed by variety of eddy engulfing structures.
These authors show that variations of the gradient Richardson number
, Ri, defined as Ri = (g/T)(dT/dz)[(dV.sub.x/dz.sup.)2] correlate strongly with variations in the ballooning activity of Erigone arctica.
The principal parameter that controls a relative effect of buoyancy is the Richardson number
Ri, defined as Ri = Gr / [Re.sup.2], where, Gr is Grashof number, and Re is Reynolds number.
They have added also, the effects of Richardson number
on a rate of heat transfer.