The Eckert number is a dimensionless number named after Ernst R. G. Eckert. The Eckert number is defined as the ratio of the advective mass transfer to the heat dissipation potential.
The Eckert number provides a measure of the kinetic energy of the flow relative to the enthalpy difference across the thermal boundary layer. It is used to characterize heat dissipation in high-speed flows for which viscous dissipation is significant.
The Eckert number is defined as:
u is the local flow velocity [m/s]
cp is the constant-pressure specific heat capacity [m2/K.s-2]
∆T is the temperature difference between wall and local temperatures [K]