Kelvin Waves with Helical Beltrami Flows Structure

GONZÁLEZ, R., SARASUA, G.L., COSTA, A.

PHYSICS OF FLUIDS

AIP

Año: 2008 vol. 20 p. 2 - 12

1070-6631

In this work we show that when  an inviscid axisymmetric Rankine flow  experiences  a soft expansion  rotating Kelvin waves (RKW) can be excited. Downstream the region where the expansion occurs (the transition region)  the resulting flow can be expressed as the  addition  of a Rankine and a Beltrami flow. The Beltrami constant is determined from the Rankine upstream flow,  and the helix pitch of    the $n=1$ mode results from the boundary conditions downstream. Finally, a discussion of the process  leading to  oscillatory flow and a conjecture about the topological background that sustains  the  Beltrami flow structure are offered.