mass flow

mass flow

 or convection

In physiology, the mechanism responsible for movement of air from the atmosphere into the lungs and for movement of blood between the lungs and the tissues. It is one of two principal mechanisms of exchange by which oxygen and carbon dioxide move between the environment and the tissues, the other being diffusion. Local flows (e.g., through skeletal muscles during exercise) can be increased selectively, increasing the exchange of gases between tissue cells and the capillaries.

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mass flow [′mas ′flō]

(engineering)

A pattern of powder flow occurring in hoppers that is characterized by the powder flowing at every point, including points adjacent to the hopper wall.

(fluid mechanics)

The mass of a fluid in motion which crosses a given area in a unit time.