In transport problems when we have simultaneous heat and mass transfer, sometimes we quantify the relative strength of the transfer phenomena using the following dimensionless numbers: • Prandtl number (Pr), relative ratio of momentum diffusivity to thermal diffusivity:
• Schmidt number (SC), relative ratio of momentum diffusivity to mass diffusivity:
• Lewis number (Le), relative ratio of thermal diffusivity to mass diffisivity. .
We can easily see that the Lewis number is a ratio of the Prandtl number and the Schmidt number (Le=Sc/Pr). When we are formulating pi terms of transport problems, can all three numbers (Pr, Sc, Le) appear at the same time as three pi terms describing a single transport problem?