The hydraulic diameter, abbreviated dh, is used to calculate the Reynolds Number, friction factor or for calculating pressure drop across two points. For most geometries, the hydraulic diameter, or characteristic length, is not equal to the diameter of the shape. The calculation below is an example of the hydraulic diameter when the shape is an isoceles triangle flowing area.
Hydraulic Diameter of an Isosceles Triangle calculator
Hydraulic Diameter of an Isosceles Triangle formula