Room airflow prediction is one of the important steps in the development of efficient and comfortable atmosphere inside an enclosed space. Comfortable indoor environments can be achieved by air-conditioning/ventilation systems. Air-conditioning is used to provide thermal comfort and to increase industrial productivity. Proper installation of any air-conditioning system is necessary to obtain optimum comfort without any adverse effects. Therefore, the analysis of airflow is important, to solve the purpose of airflow distribution inside any enclosed space. Airflow mainly depends upon the environment, building structure and occupants. Earlier, very extensive research has been carried out on various aspects of airflow inside/outside the building. In the present study, a comparative study is done for the slot-jet type diffuser and ceiling type diffuser for various conditions. The location of inlet and outlet ports certainly altered the flow of air inside a room, hereby discussed in this study. Simulation tools use mathematical models to solve practical airflow problems, and determine the airflow patterns for different conditions affecting the airflow. The mathematical models developed for the simulation techniques may not be valid for all the practical ranges of the airflow properties. These mathematical models need to be modified with change in the range of airflow properties, as the airflow patterns do not follow the same mathematical model for all ranges of variables. Hence, in the present work, the results of numerical simulation are validated with the results of flow visualization experiments In the present study, laminar and turbulent airflows are studied for slot jet type diffuser and ceiling type diffuser using numerical simulation. The velocity and temperature distributions for laminar flow in a room are determined by solving the Navier-Stokes equations, along with the continuity and energy equations. The Boussinesq approximation is used. The governing equations are discretized using a finite volume method. The pressurevelocity coupling is handled using the SIMPLEC algorithm. A low Reynolds number (LRE) version of k-ε model for turbulent flow is used in the present study, with special treatments through damping functions. Additional equations are solved to determine the distribution of contaminants and local age of the air. Room airflow is also studied experimentally with obstacles, for the slot type diffuser.