Incompressible turbulent fluid flow in aerodynamically rough channels is investigated
using direct numerical simulations. A comprehensive database of simulation
data for rough surfaces with different topographical properties has been developed
for 17 industrially relevant rough surface samples. It includes numerous commonlyseen
industrial rough surfaces such as concrete, graphite, carbon-carbon composite
and ground, shotblasted and spark-eroded steel. Other surfaces such as cast, filed
and gritblasted steel are also studied, along with replicas of ship propeller surfaces
eroded by periods of service. The Reynolds number considered is Reτ = 180, for
which the flow is in the transitionally rough regime. A study with variable δ/Sq ratio
while keeping S
+
q
constant, where Sq is the root mean squared roughness height,
is conducted for one of the samples with the mean profiles showing convergence
for δ/Sq >≈ 25. A Reynolds number dependence study is conducted for two of the
samples with Reτ up to 720 showing a more complete range up to the fully rough
flow regime, allowing the equivalent sandgrain roughness height, ks
to be computed.
A correlation based on the frontal and wetted roughness area is found to be superior
to the surface skewness in predicting ∆U
+ based on the topographic surface
parameters
