The Role of Vorticity Dynamics in Vortex Breakdown.pdf

The Role of Vorticity Dynamics in Vortex Breakdown David L Darmofal  Computational Aerospace Sciences Lab oratory Department of Aeronautics and Astronautics Massachusetts Institute of Technology Cambridge MA Abstract ow will b e applied The radial azimuthal and axial ve lo cities are u v and w similarly the radial azimuthal and The role of vorticity dynamics in vortex breakdown is ex axial vorticity comp onents and are amined in a theoretical and computational study Under the v assumptions of steady incompressible axisymmetric invis cid ow a theory is develop ed concerning the interaction z of vortex tilting and stretching in the breakdown pro cess u w This analytic theory is then conrmed using an unsteady z r incompressible axisymmetric viscous ow solver The theo r v retical and computational results are in excellent agreement r r Both results p oint towards the imp ortance of vortex tilt ing in initiating vortex breakdown The agreement b etween An axisymmetric streamfunction can b e dened as the inviscid theory and viscous computations indicates that breakdown is primarily an inviscid pro cess A measure of the susceptibility to breakdown is develop ed from the invis u r z w