An agglomeration multigrid method was applied to numerical calculation of rotor forward flight flow based upon the unstructured dynamic overset grids.Two overlapping subareas could be generated speedily from original global unstructured mesh

while the original hole fringe and donor elements could be established without using a background grid.And

the hole fringe needn't update during dynamic oversetting

and the new donor elements could be searched quickly by using a new technique without background grid.The agglomeration multigrids were generated separately in each subarea

and a three-level V cycle method was used to solve the unsteady Euler equations by dual time stepping.The flow field parameters were coupled in the overlapping area.Finally

the rotor forward flight flow was calculated.The results show that

the agglomeration multigrid method can facilitate the convergence of rotor forward flight flow effectively.