Numerical simulation of a mixed vertical ventilation system

Abstract

The following work describes the process of finding the flow and the temperature fields for a given ventilation system configuration. In order to simplify the problem, the flow was characterized as 2D, incompressible, viscous and in constant state. First, the governing equations in terms of the stream function, vorticity and Reynolds number have been developed. The obtained mathematical model for the flow field is actually a pair of coupled elliptical partial differential equations. Solving the resulting equations was performed using SOR (successive over-relaxation) methods following upwind second-order finite differences.In the second stage, the temperature field was numerically calculated using the flow field data obtained in the first stage. In fact, as expected, the flow has been advanced from the left inlet opening to the right outlet opening. Also, the main flow was creating a vortex while above the main flow large vortex has been generated and surrounded by several small vortices around it. Last but not least, Reynolds (Re) number influence on the solution nature has been expressed by flow expansion in the whole ventilation cell. Finally, comparison between different Re numbers have proved the flow type dependency on the Re number and its effect on the temperature field.

The reduction of pressure losses in thermally modulated vertical channels

“…Heating-modified flows in vertical channels are of importance in various aspects of architectural design as they can affect the performance of heating, ventilation and air conditioning systems. Passive ventilation is achieved through the so-called stack effect, whereby a density difference drives the heated air in the upward direction, thereby drawing in cool air at the base of a structure (Linden 1999; Wong & Heryanto 2004; Mortensen, Walker & Sherman 2011; Nagler 2021). Conversely, in a reverse stack effect hot air is drawn down into a cooler environment.…”

Natural convection and pattern interaction in a two-dimensional vertical slot

“…Natural convection in vertical openings is of interest in architectural design as it provides the means for passive ventilation through the so-called stack effect, whereby heated air flows in the upward direction and draws in cool air at the base of a structure (Linden 1999; Wong & Heryanto 2004; Nagler 2021). A reverse stack effect can also occur in which relatively hot air is brought down from above into a cooler environment.…”