Civil Engineering Reference
In-Depth Information
The first DNS in a channel with [KIM 87] and in
boundary layers with [SPA 88] were initially met with a
certain amount of suspicion by experimental researchers.
However, the concordance between the results found with
DNS (limited, at that time, to low Reynolds numbers) and by
measuring, alongside the significant similarity, e.g.
between the particle trajectories determined by the
simulations (Figure 3.4) and visualizations by hydrogen
bubbles (Figure 3.2) ultimately convinced the last remaining
skeptics. The period 1980-2000 was also marked by the
development of advanced measuring techniques such as
particle image velocimetry (PIV) [ADR 05] and arrays of
microsensors in microelectromechanical systems (MEMS)
4
technology [HO 98, VAL 11]. It is possible to compile a
list - by no means exhaustive - of the major publications on
experimental aspects during that period, citing [BAL 91],
[TSI 92], [HON 97], [ONG 98] and [ADR 00].
The dawn of DNS had two major consequences. The first
was advancement in research related to the identification of
coherent vortex structures due to the database of DNS
results compiled. This aspect is dealt with in detail in this
chapter. Second, again due to the complete database, the
dynamics of coherent vortices and their impact on the
structure of wall turbulence were able to be more accurately
defined by the researchers in the domain, beginning with
Robinson [ROB 91a, ROB 91b], who analyzed the DNS
performed by Spallart
[SPA 88] (Figure 3.5). One of the
fundamental questions is the regeneration of coherent
structures that sustain the turbulent activity near to the
wall. These aspects are discussed in Chapters 4 and 5 of this
topic.
4 Microelectromechanical systems; also see [TAR 10b] for a review of the
subject.
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