Convective heat transfer from internal room surfaces has major effect on the thermal comfort, air movement and heating and cooling loads for the room. Recent studies have shown that the values of convective heat transfer coefficient used in building thermal models greatly influence the prediction of the them1al environment and energy consumption in buildings. In computational fluid dynamics ( CFD) codes for room air movement prediction accurate boundary conditions are also necessary for a reliable prediction of the air flow.

The numerical evaluation of room air movement is made by systematic discretization of space and the dependent variables. This makes possible to replace the governing differential equations with simple algebraic equation. The dynamic model of the temperature is based on the energy balance equation, considering a given flow field. The temperature in a given control volume depends on the temperatures of its corresponding neighbours. This form of the model is. not appropriate for control theory.

At present, Computational-Fluid-Dynamics (CFO) with the 'standard' k-e model is a popular method for numerical simulation of room airflow. The k-e model needs a lot of computing time and large a computer. This paper proposes a new zero-equation model to simulate three dimensional distributions of air velocity, temperature, and contaminant concentrations in rooms. The method assumes turbulent viscosity to be a function of length-scale and local mean velocity.

Airflow behavior inside a cleanroom with vertical unidirectional flow has been investigated. The design parameters, such as porosity and height of raised floor, width of clean room and inlet velocity profile, which affect the uniformity of air velocity distribution inside the cleanroom have been studied computationally. The Reynolds-averaged Navier-Stokes equations governing the flow are solved using a finite-volume code ST AR-CD. The standard k-e turbulence model has been used.

A two-dimensional turbulence k-e model is used to predict distribution of air velocity, temperature and turbulence kinetic energy in an air-conditioned room using ceiling air supply. Mixing characteristics of the airflow are analyzed under different air supply velocities and temperatures. A modified Archimedes number is correlated with the parameter ·characterizing heat transfer, ventilation system, and turbulence kinetic energy of room air flow. Significant correlations have been shown.