LES of shock wave / turbulent boundary layer interaction

31
Figure 3.2: Instantaneous z−vorticity component ω z in x − y section.
3.2 Mean flow and statistical analysis
The mean-flow characteristics for the reference section x r are summarized
and compared with the experiment in table 3.1. δ 1 and δ 2 are displacement
and momentum thickness, respectively. Re δ2 is the Reynolds
number based on the free-stream velocity, momentum thickness and viscosity
at the wall. H 12 is the shape factor. The agreement of δ 0 , δ 1 ,
δ 2 , H 12 with the experiment is good. The computed skin-friction coefficient
C f differs more significantly from the experiment with an uncertainty
of about ±10%. However, the discrepancy is within the limits of
experimental-data scatter, as shown in figure 3.3. In this figure several
experimental data sets C f versus Re δ2 , taken from Fernholz & Finley
(1977, 1981), are shown along with our computed values and the experimental
reference values at station E1. An empirical fit of the experimental
data is shown by the dashed line, using a von Kármán-Schoenherr
incompressible skin-friction formula
C finc =
1
17.08(log 10 Re θinc ) 2 + 25.11log 10 Re θinc + 6.012 ,