dwf_SwameeJain.bas

Attribute VB_Name = "DWf_SwameeJain"
Function f_SwameeJain(D As Double, Re As Double, aRou As Double) As Double

' Calculates the Darcy-Weisbach friction factor for pressure loss calculations
'   via explicit equation by Swamee,P.K.&Jain,A.K.
'   by Tol,Hakan Ibrahim from the PhD study at Technical University of Denmark
'   PhD Topic: District Heating in Areas with Low-Energy Houses

' INPUTS
'    aRou     : Absolute roughness of pipe          [mm]
'    D        : Inner diameter of the pipe          [mm]
'    Re       : Reynolds Number                     [-]

' Checking algorithm limitations
If Re < 5000 Or Re > 100000000 Then
    'MsgBox "Error: Swamee&Jain algorithm is valid for a Reynold range as in 5000<Re<1e8"
    f_SwameeJain = CVErr(xlErrNA)
End If

If aRou / D < 0.000001 Or aRou / D > 0.05 Then
    'MsgBox "Error: Swamee&Jain algorithm is valid for a relative roughness range as in 1e-6<eps/D<0.05"
    f_SwameeJain = CVErr(xlErrNA)
End If

' Fasten your seat belts - Formulation in Run
f_SwameeJain = 0.25 / (LogBase(((aRou / D) / 3.7 + 5.74 / Re ^ 0.9), 10)) ^ 2

End Function