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A simply mathematical model is used to investigate the hydrodynamics in a gas-solid jetting fluidized-bed gasifier．The model intmduces two additional force terms in both the gas-and solid-phase momentum equations of Gidaspow’s inviscid two。fluid model Sand with a density of 2660 kg/m3 and a diameter of 500 μm，belonging to Geldart Group B classification，is employed as the solid phase Numerical computation is carried out in a 0.57 m× 1.00 m two-dimensional rectangular bed using a commercial CFD code，CFX4.4，by invoking user-defined Fortran subroutines．The model shows its capacity of simulating the gas fluidization process realistically from a fixed to fluidized bed．Time．averaged bed pressure drop obtained is in fair agreement with theoretical calculation when the inlet gas velocity is the minimum fluidization velocity．The effects of the distance between two nozzles and jet gas velocity on Jetting phenomena are explored in the fluidized bed with two vertical jets．The computational results show that three flow patterns(isolated,coalescence and transitional Jets)depend on the combined effects of nozzle distance and jet gas velocity,and have a strong influence on the solid circulation pattern．Moreover,jet penetration height increases with increasing the jet gas velocity．The above findings demonstrate that this simple model has a potential advantage for capturing the gas-solid flow behaviors in a large jetting fluidized bed by companng to the two-fuid model based on the granular kinetic theory．