Question

1. When does any material flow?
2. What happens exactly when it flows?
3. Which anomalies in the material is responsible for the initiation of the flow?

Answer 1

1. Any material flows when it is in a fluid state (liquid or gas) and an unbalanced external force acts on it, or when there is a difference in temperature, density, or pressure within it. For example, water flows when it is tilted or heated unevenly; air flows when pressure differences exist.
2. When a material flows, its particles or layers move relative to one another from one place to another. In the case of uneven heating, the warmer, less dense part rises and the cooler, denser part sinks, setting up convection currents. This transfers heat and matter continuously.
3. The density anomaly, that is, the difference in density caused by unequal distribution of temperature and, in ocean water, also salinity, is responsible for initiating flow. The less dense warm material rises and the denser cold material sinks, producing movement.