This study investigates how the inlet gas velocity and the louver angle affect the granular flow of spherical particles in two-dimensional moving (and fixed) granular filter beds with a symmetric louvered-wall. The methodology of Tsuji et al. [1] was extended to facilitate this gas-solid flow field calculation. The calculation procedures were as follows: (1) determination of the coordinates of each spherical particle and calculation of the void fraction of the granular bed; (2) calculation of the updated two-dimensional gas velocity field using the SIMPLE method [2]; (3) determination of the drag force acting on the particle using the equation of Fan and Zhu [3], and (4) obtaining the contact force, velocity and displacement of each particle using the DEM model devised by Cundall and Starck [4]. In addition, a digital camcorder was used to record the flow pattern histories of the spherical particles in cross-flow moving (and fixed) granular filter beds with a symmetric louvered-wall. The numerical predictions were compared with the experimental results in a qualitative manner. In a fixed granular bed, the bubble area obtained, which is based on numerical predictions agrees with that obtained experimentally, and increases with louver angle. However, in a moving granular bed, the bubble area obtained by numerical modeling increases with louver angle, but the bubble area obtained experimentally decreases with increasing louver angle. Additionally, this investigation demonstrates both numerically and experimentally that the bubble area increases with air inlet velocity in both fixed and moving granular beds.