1. Transfer phenomena
The most well known transfer phenomena are:
Definition : a) Heat transfer:
in which the transferred quantity is heat (temperature or energy), this transfer occurs between two zones with different temperatures, it always occurs from the higher temperature to the lower temperature. The temperature difference is called the driving force of heat transfer.
Definition : b) Mass transfer:
in which the transferred quantity is matter (mass concentration), this transfer occurs between two zones with different mass concentrations. It always occurs from the higher concentration to the lower concentration. The concentration difference is called the driving force of mass transfer.
Definition : c) Momentum transfer:
in this process, the quantity transferred is momentum (velocity). It occurs between two entities with different velocities, always from the entity with the higher velocity to the one with the lower velocity. The difference in velocity is referred to as the driving force of momentum transfer.