In the development of driver airbags (DABs), the out-of-position (OOP) test is important in reducing the risk of injury to occupants close to airbag modules. Airbag deployment simulations are valuable in predicting occupant protection in the development and design stages. One of the key elements of airbag deployment behavior is the be- havior of gas jets from the inflator. Here, we conducted visualization experiments using the Schlieren method to understand the gas flow behavior of disk-type inflators. Gas flow from an inflator with a retainer showed strong directivity. Gas flow simulations were conducted with a general-purpose finite element program, LS-DYNA. Using the corpuscular particle method (CPM), in which jet direction and cone angle of gas diffusion were essential ele- ments, gave good reproducibility. We compared simulations with experiments of DAB deployment behavior and analyzed the effect of gas flow on deployment behavior. By implementing actual gas flow in the CPM, we improved the accuracy of airbag simulation using DAB OOP positions 1 and 2 as demonstrators. The reproduction of gas flow was a major factor in the reproduction of DAB deployment behavior.