The equivalent sand grain height approach is widely used in modern Computational Fluid Dynamics (CFD) calculations on rough surfaces. I am conducting a few simulations against available experimental data on a rough aerofoil. The experiment reported the rough surfaces were sandpaper P80 and grit 36 without mention the equivalent one. Surface roughness research is not a field I'm familiar with, because I concentrate on roughness modeling in aerodynamics. So I tend to ask if any one who knows any data or correlations to sandpapers. Don't mentioned the method in Boundary Layer Theory by Schlichting, because the experiment didn't provide me sufficient data to use that. Dirling's correlation is also not viable because I can't do the roughness geometrical measurement.
Hello,
This reference will give you an estimate of the Ra if you can't measure it yourself:
http://www.google.fr/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&ved=0CC4QFjAA&url=http%3A%2F%2Fwww.nanovea.com%2FApplication%2520Notes%2FSandPaper.pdf&ei=NVc8Upi1IcGhtAbYkoEg&usg=AFQjCNEiBt6TAF6dYe-e9UcGCfnMzeFwtg&sig2=93ZtG1gCi2XNZc13Sj6Oag&bvm=bv.52434380,d.Yms
And you will find a few Ra/ks correlations in Bons (2010), but good luck choosing one:
http://turbomachinery.asmedigitalcollection.asme.org/article.aspx?articleid=1468122
Hope this helps,
Alex.
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