Sheared-flow-driven vortices in a magnetized dusty electron-positron plasma

It is shown that sheared plasma flows can generate nonthermal electrostatic waves in a magnetized dusty electron-positron plasma. Linearly excited mod es attain large amplitudes and start interacting among themselves. Nonlinea rly coupled modes self-organize in the form of coherent vortices comprising a vortex chain and a double vortex. Conditions under which the latter appe ar are given. The relevance of our investigation to space, astrophysical, a nd laboratory plasmas is pointed out.