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Fanno Flow

Compute star-state relations for adiabatic duct flow with friction.

shock
visual calculatorCompressible Flow

Read the flow shape before trusting the number.

This page turns a CFD setup into regime, scale, and dominant-effect cues. Adjust the calculator below and compare the moving graphic with the computed result.

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compressiblefannoduct flowfriction
formula
KaTeX rendered
4 f L* / D = (1 - Mˆ2) / (gamma Mˆ2) + ((gamma + 1) / (2 gamma)) ln[(gamma + 1) Mˆ2 / (2 + (gamma - 1) Mˆ2)]\begin{aligned}\text{4 f L* / D = (1 - M\^{}2) / (gamma M\^{}2) + ((gamma + 1) / (2 gamma)) ln[(gamma + 1) M\^{}2 / (2 + (gamma - 1) M\^{}2)]}\end{aligned}
ASCII source4 f L* / D = (1 - M^2) / (gamma M^2) + ((gamma + 1) / (2 gamma)) ln[(gamma + 1) M^2 / (2 + (gamma - 1) M^2)]
M0.500000
T/T*1.142857
P/P*2.138090
P0/P0*1.339844
U/U*0.534522
4 f L*/D1.069060
(s* - s)/R0.292553
compressiblefannoduct flowfriction