His Fig. 2 is a look up for e/D values. I plotted the Winter/Summer friction factor numbers on the figure and the e/D values range as thus:
or
RC: 0.00015 to 0.0006
CC: 0.0005 to 0.00112
In comparison, previous Master's work found e/D values for
RC: 0.000075 to 0.00045
CC: 0.000075 to 0.00095
These are significantly smaller values for the friction factors we see on the pipelines.These values were based on Colebrook/White equation.
I'm seeing Reynolds numbers in the 10^4 (1L) to 10^5 region. I think C/W is only good in the transition region. I'll need to verify.
One of the things I do like that Moody did was to plot all the different equations (Von Karman/ Pandlt/Nikraduse, Colebrook, Rouse) against each other.
Had an "aha" moment.
We pump in the transition zone (purple box below). I've known this for a while.
Moody also discussed how difficult it is to come up with a real absolute roughness value. The values the industry uses are the ones based on the sand grain sizes from Nikraduse. Moody indicates the engineer should rely instead on the hydraulic roughness, or e/D.
From Moody:
When the thickness of the laminar layer, which decreases with increasing Reynolds number, becomes so small compared to the surface irregularities that the laminar flow is broken up into turbulence, the flow conditions pass over into the zone of "rough pipes" with complete turbulence established practically throughout the flow. Viscous forces then become negligible compared to inertia forces, and f ceceses to be a function of the Reynolds number and depends only upon the relative roughness, giving horizontal lines of constant f in the chart.
Which means the evidence I see with the cyclical f versus Reynolds numbers values DO have significant viscous forces at work. So can this mean that we could have differing flow regimes based on water properties of the water (density/temperature/etc)?
Moody also mentioned the results of Colebrook plots that produced results from an Ontario large diameter penstock. The f v. Re values put the results close to very smooth pipe.
Another item to vet out is the absolute roughness/boundary layer values. Appearently, Moody based his work on a constant value 6.08, which is considered somewhat high.
Also, Rouse showed the e/D values Colebrook found, fall within experimental scatter.
So now I'm starting to think about how this relates to biofilm. These values are all based on static roughness measurements. I think I may want to consider abandoning the pipe roughness v. biofilm roughness in favor for a dynamic hydraulic roughness of the pipe.
I do see cycical variation. Do I tie it to temperature? Viscocities? I lean toward viscosity since previous work showed temperature was somewhat independent of other water properties (the linear regression class work).
Could this be significant work?
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