Coaxial jet
 

how can i mesh a coaxial jet in ansys workbench so as to obtain a converged solution.
this is my first time of using fluent and i have read some materials on it but the algorithm it is using for meshing is not correct as suggested by the software.

kindly help and guide on how i can use a bias mesh for a 2d rectangular domain with the left edge split into three to accomodate the inner pipe flow, annular pipe flow and the environment but the right edge is just a single edge.