Vibration driven compartmentalized granular gas is capable of clustering in one of the compartments，which is an effect called Maxwell demon phenomenon. One of the keys for understanding the Maxwell demon phenomenon is establishing a flux model. Based on granular hydrodynamics，Eggers deduced a simplified flux model which has been successfully used in describing the spontaneous symmetry breaking of granular gas in the compartmentalized system，but so far has not been able to predict the oscillation phenomenon of bidisperse granular gas. Experimentally studying the flux of mono-disperse granular gas in one compartment，we modify the flux model of Eggers to fit the experimental results. The modified flux model can be extended to the bidisperse granular case，and the oscillatory state can be well obtained by this modified flux model.