air flow

The airflow in buildings involves a combination of many different flow elements. It is, therefore, difficult to find an adequate, all-round turbulence model covering all aspects. Consequently, it is appropriate and economical to choose turbulence models according to the situation that is to be predicted. This paper discusses the use of different turbulence models and their advantages in given situations. As an example, it is shown that a simple zero-equation model can be used for the prediction of special situations as flow with a low level of turbulence.

A three-dimensional, large eddy simulation (LES) model developed for studying the transport of smoke and hot gases during a fire in an enclosure is described. The model uses finite difference techniques to solve the Navier-Stokes equations with an approach emphasizing high spatial resolution and efficient flow-solving techniques. The model uses the Smagorinsky subgrid-scale model. The LES model with Smagorinsky subgrid-scale model was applied to ventilation aiiflow in a three-dimensional room.

The Field and Laboratory Emission Cell (FLEC) is a tool for non-destructive emission testing of materials with even surfaces. Measurement of air velocities inside the cell showed an inhomogenous flow field with a high-velocity area around the inlet axis and an area of comparatively low air velocities perpendicular to the inlet axis. These results suggest that punctual emission sources may lead to different VOC-concentrations depending on the position of the source.

The subject of this paper is the experimental determination of the flow characteristics of three-dimensional wall jets. The jets were produced from a diffuser with a rectangular outlet. The diffuser outlet size and flow rate were varied to produce both low and high outlet aspect ratios and Reynolds numbers. Velocity profile measurements were made to determine the centerline velocity decay and the extent of the lateral and vertical spread of the jet.

In this paper, new requirements for the characteristics of anemometers used for low-velocity measurements indoors, as well as requirements for the signal processing, are presented The static calibration, dynamic response, and temperature compensation of the anemometers, as well as the directional sensitivity and the design of the velocity transducer, are considered, together with the period and the sampling rate of the measurements.