Keyur Kanade
Ansys Employee


You are absolutely correct. KH instability requires the following conditions: two uniform flow of different velocity and density that are incompressible and inviscid. The instability sets in when the following instability condition is met.

(U1-U2)^2 > g(rho1^2 - rho^2)/(alpha * rho1 * rho2)


alpha = 2*pi / lambda,

lambda is the wavelength of the disturbance,

subscript 1 and 2 refer to fluids 1 and 2.

This instability manifests as roll-up vortices examples of which include the famous Jupiter's Red Spot and cloud formation.

I hope this helps.

Thank you.