What is the hydraulic diameter ? The hydraulic diameter, defined as
the ratio in between 4 times the flow section over the wetted
perimeter, allows, for non circular flows, to define an equivalent
diameter which allows to perform fluid dynamic calculation.
What is meant by hydraulic diameter ?
The hydraulic diameter is used for non-circular flow and is calculated thanks to the following general formula : DH=4*(flow section)/(wetted perimeter)
The Hydraulic Diameter formula for 2 simple geometries : rectangular duct and annulus are given below.
You can access here
an Excel Calculator to calculate the hydraulic diameter
Mecanique et Rheologie des fluides en genie chimique, Noel Midoux, Lavoisier Tec et Doc, page 197