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Question 6.12: For the conditions described in Examples 6.9 and 6.10 assume......

For the conditions described in Examples 6.9 and 6.10 assume λ = 0.017, calculate the Reynolds roughness number and determine which of the simplified empirical equations can be applied.

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Reynolds roughness number Re* = Re(k/D) (λ/8)^{{1}/{2}}

From Example 6.10, Re = 2.821 × 10^{6}, k/D = 0.000500, λ = 0.017

Re* = 2.821 × 10^{6} \times 0.000500 \times ({0.017}/{8})^{{1}/{2}}

Re* = 65

For Re* > 60 the flow is in the rough turbulent zone, so the Manning equation would be appropriate.

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