Ans: 1. When a solid and fluid at different temperatures come into contact, the temperature at their point of contact must be the same.
2. For example, when a cold fluid at temperature T∞ flows over a hot surface with temp Ts, the fluid must attain temperature Ts at the point of contact.
3. Therefore, fluid and solid surfaces must have the same temperature at the points of contact. This is known as no temperature-jump condition.