I would use a UDF. Use the mode either 1 or 2 to return the value or the type

Function Fluid_Flow(mode As Integer, re As Single)

Select Case mode
Case 1
Select Case re
Case Is < 2300
Fluid_Flow = "Laminar"
Case Is = 4000
Fluid_Flow = "Transitional"
Case Else
Fluid_Flow = "Turbulent"
End Select
Case 2
Select Case re
Case Is < 2300
Fluid_Flow = "add formula"
Case Is = 4000
Fluid_Flow = "add formula"
Case Else
Fluid_Flow = "add formula"
End Select

End Select

End Function


"Steve M." wrote:

I want to program excel to check whether fluid flow is laminar, transitional,
or turbulent and use corresponding equations to solve for friction.

Laminar (re<2300) - friction = Re/64
Transitional (2300<re<4000) - friction use Churcill equation
Turbulent (re4000) - friction use colebrooke iterative equation

I have the flow type listed in one column and I would like the corresponding
friction factor to be listed in the adjacent column.

--Steve