The increasing incidence of airborne transmitted diseases indoors has prompted the attention ofstudying expiratory droplet dispersion and transport in built environments. Droplet dispersion in aroom under the conventional well-mixed and displacement ventilation is simulated. In this work, asource (i.e. a patient) and a receptor (i.e the susceptible object) were located in a mechanicalventilated room. This study evaluated droplet dispersion and mixing under well-mixing anddisplacement ventilation scheme.