We perform a computationl study of front speeds of G-equation models in time dependentcellular flows. The G-equations arise in premixed turbulent combustion, and areHamilton-Jacobi type level set partial differential equations (PDEs). The curvature-strainG-equations are also non-convex with degenerate diffusion. The computation is based onmonotone finite difference discretization and weighted essentially nonoscillatory (WENO)methods. We found that the large time front speeds lock into the frequency of timeperiodic cellular flows in curvature-strain G-equations similar to what occurs in thebasic inviscid G-equation. However, such frequency locking phenomenon disappears inviscous G-equation, and in the inviscid G-equation if time periodic oscillation of thecellular flow is replaced by time stochastic oscillation.