Graetz number

The Graetz number (Gz) is a dimensionless number used in the field of heat transfer, particularly in the analysis of heat transfer in ducts and pipes. It is a measure of the relative importance of heat conduction to heat convection in a flow situation. The Graetz number is defined as: \[ Gz = \frac{L c_p}{k A} \] Where: - \(L\) is the characteristic length (often the length of the duct or pipe).