In this paper the cavity flow has been investigated with Fokker-Planck approach (FP). Our surveys showed recently Fokker-Planck approach has been widely used to model rarefied gases; However, the accuracy of this algorithm is unknown. The results have been compared with direct simulation Monte Carlo (DSMC). The biggest difference between DSMC and FP comes back to substitution of collision part with moment calculations in FP. Our results show that by increasing wall speed the FP results becomes more compatible to DSMC i.e. the results with U=100 are different with DSMC; However, the results with U=300m/s is nearer to DSMC. We also observed cold to hot heat transfer with FP and DSMC in some regions; where viscous dissipation can be balanced with expansion cooling. We will show that it can be occurred at low wall speeds. We observed that in comparison with DSMC, FP could work with coarser time step and grid spacing.

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