Zonal models using loop equations and surface drag cell to cell flow relations.

Zonal models have been proposed to bridge the gap between the whole-building macroscopic modeling methods of programs like CONTAM or COMIS and the more detailed microscopic modeling metho.ds based on solutions of the time-smoothed Navier-Stokes equations for room airflows. This paper identifies a critical shortcoming of conventional approaches to zonal modeling by introducing alternative approaches a) to formulate the key cell-to-cell flow relations upon which zonal models are based and b) to assemble the zonal system equations. Conventional cell-to-cell flow relations based on boundary power-law formulations appear to capture gross aspects of the flow structure in rooms but fail by orders of magnitude to properly model the resistance offered to airflow. Cell-to-cell flow models based on surface drag momentum transfer may mitigate this shortcoming and appear to capture room airflow structure more accurately. Furthermore, these flow models offer a means to provide quick approximate solutions of room airflow problems (i.e., based on linear formulations of cell-to-cell flow relations) that may be acceptable for certain purposes or can be used as initial estimates for the solution of the more accurate nonlinear formulations of zonal problems.