Keyword(s) Hydraulic Diameter. For a new search enter search key word(s) then click GO GO
Calculate the dimensionless relative roughness or roughness number for pipes and rectangular ducts.
`rr = (ir) / (ID) `
where :
rr = relative roughness or roughness number ir = surface roughness ID = pipe inside diameter
For rectangular ducts the hydraulic diameter is used
`ID = 2 w h / (w + h) `
ID = hydraulic diameter w = duct width h = duct height