Reading the Moody chart with a linear interpolation method.

Area of Science:

• Fluid Dynamics
• Engineering

Background:

• The Moody chart is a widely used tool for determining friction factors in pipe flow.
• Linear interpolation is commonly employed to read values from the Moody chart.
• A potential source of error, the pseudo-midpoint effect, has been identified.

Purpose of the Study:

• To analyze the error introduced by the pseudo-midpoint effect when using the Moody chart.
• To quantify the magnitude of this error in typical applications.

Main Methods:

• Analysis of the linear interpolation method applied to the Moody chart.
• Calculation of maximum error due to the pseudo-midpoint effect.

Main Results:

• The pseudo-midpoint effect arises from the linear interpolation method used with the Moody chart.
• The maximum error caused by this effect is approximately 4%.

Conclusions:

• The pseudo-midpoint effect introduces a maximum error of around 4% in Moody chart readings.
• This error is considerably smaller than the chart's inherent accuracy limitations (literature suggests ~15%).