Application of numerical flow simulation to flow around buildings

Movie of 2D vortex shedding past a chimney [compressed AVI-File 5,84 MB]

2D vortex shedding - animation of the transient process as a contour plot
[compressed AVI file 5,84 MB]

With regard to air flow processes around buildings, the methods of numerical flow simulation represent an interesting alternative to wind channel tests of down-scaled models.

Analogous to experimental investigations, the following important questions can be answered regarding the construction of strongly wind loaded buildings:

static and dynamic wind loads
influence of surrounding buildings on air flow profile
drag and lift coefficients depending on wind direction
wind induced foundation forces and torques (static and dynamic)

With measurements, the prediction of pressure and forces is normally performed only at few distinct points whereas numerical flow simulations reveal pressure distributions for the entire outer cover of the building.

As a simple example of a building susceptible to vibrations, the simulation results of flow around a chimney are shown. The vortex shedding past the chimney results in dynamic pressure loads on its surface.
With this model, the influence of different wind directions and speed can easily be analysed.
Boundary conditions for static and dynamic strength analyses are, thus, readily available.

These static and dynamic pressure conditions on the surface of the building are not only important for the static design of the building structure but they also need to be considered for the conception of airing systems. Essential questions related to this are:

airing efficacy and airing rate
smoke-off efficacy
ensuring desired comfort standards

Using the methods of numerical flow simulation, the analysis and related optimisation of airing systems can be performed without the expensive model building necessary for wind channel tests.

Snapshot of a 2D-flow past a chimney - static pressure distribution and velocity vectors

	DOWNLOAD high resolution animation 3D vortex shedding past a square chimney - contour plot of velocity in two planes and static pressure distribution on surface [compressed AVI file 11,8 MB]	DOWNLOAD high resolution animation Streak lines of flow around a chimney [compressed AVI file 12,2 MB]
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