Attribute VB_Name = "Module333"
Public Function FrFact(REY As Double, ED_dimensionless As Double) As Double
Rem          Friction Factor VBA Function
Rem          For personal use only. 
Rem          Code developed for use in Louisiana State University course PETE 4051
Rem          "Reserve Evaluation and Reservoir Management"
Rem          Spring Semester 2002. Adapted for distribution in connection with 
Rem          the Oklahoma Geological Survey.
Rem          Written By: Dr. R. G. Hughes
Rem                      2/1/2002
Rem          After Two-Phase Flow in Pipes by Brill and Beggs
Rem
 
   Dim FGI, DEN As Double
   Dim I As Integer
   
      If (REY <= 2000) Then
         If (REY > 0#) Then
            FrFact = 64# / REY
         Else
            FrFact = 0#
         End If
         Exit Function
      Else
         FGI = 0.0056 + 0.5 / REY ^ 0.32
         For I = 1 To 10
            DEN = 1.14 - 2# * Log(ED_dimensionless + 9.34 / (REY * (FGI ^ 0.5))) / Log(10)

            FrFact = (1# / DEN) ^ 2
            Diff = Abs(FGI - FrFact)
            If (Diff <= 0.0001) Then
               Exit Function
            End If

            FGI = (FGI + FrFact) / 2#
         Next I
       
         FrFact = FGI
      End If
      
End Function