The objective of this study is to accelerate the convergence of multigrid solvers on the high Reynolds
number turbulent flows using implicit preconditioners. Fourier analysis has been performed to
assess the aspect of preconditioning characteristics of the popular implicit methods such as ADI
and DDADI schemes. Through this analysis, it is shown that the DDADI preconditioner has
better characteristics than the ADI scheme on the eigenvalue clusering. Numerical tests on the
2-D compressible turbulent flows past an airfoil has been performed to verify the Fourier analysis
with the Spalart-Allmaras and Baldwin-Lomax turbulence models. Results by the numerical tests
show the consistent result with the Fourier analysis.