Smoking or non-Smoking?

by AFC

Smoking has well documented detrimental health effects in both those who smoke and the passive smokers around them. Recent initiaitives by various governments around the world have seen smoking banned within restaurants and bars. Some of these restaurants have claimed that the lack of choice has forced a significant proportion of their customer base elsewhere and so affected their profits.

Traditional solutions require smoking sections to be physically cut off from non smokers but this is not ideal as the customers are segregated and introduces problems when the dividing doors are opened.

In light of this need Air Flow Consulting (AFC) based in Zurich who are experts in the computer simulation of air, contaminant, and smoke flows within buildings have set up a demonstration project to reduce environmental tobacco smoke (ETS) within a café restaurant without the use of doors.

The required air flow rates and openings between the smoking lounge and the non-smoking area have been optimized by AFC using Computational Fluid Dynamics (CFD) models to predict smoke movement.

For the correct prediction the smoke distribution, the buoyant flow around the persons, as well a the geometric details of the restaurant have to be modeled accurately. A generic two tier restaurant with smoking and non smoking areas was generated using a CAD model.

Automatic meshing

The computational mesh or grid was generated with Harpoon, a fully automatic hex dominant mesher. Harpoon has the ability to go directly from the original CAD model without the need for user intensive clean up and preparation steps. This allowed AFC to optimize the layout of the restaurant and the location of the the smoking and non smoking areas with minimum effort.

The mesh that Harpoon generated consisted of 1.43 Million cells and took 30 minutes to set up and about 1 minute to mesh.

The airflow was predicted using CFX 10.

Increased Productivity

In similar projects with using a range of different meshers the meshing process took at least 50% of the total project setup time. So meshing was a significant bottleneck for improving efficiency, reducing costs and providing the customer with the best value for money. In this example the meshing time was reduced to about 5% of the total time. Due to this dramatic reduction the left over time can be used to run more simulations providing a more accurate understanding of the flow characteristics.

AFC Air Flow Consulting in Zurich are experts in the computer simulation of air, contaminant, or smoke flows in buildings with CFD, as well as energy simulation of buildings, people evacuation of public buildings, and simulation of explosions including FEM of structural deformation.

The results of the CFD simulations show the smoke distribution for the different ventilation systems. A significant reduction in smoke transport has clearly been.achieved.