In a coffee processing plant I dealt with they had a sequence of machinery. Large bins of coffee would be brought in from farms. The bins had doors at the bottom you could open.
The bin would be placed above a chute that dropped coffee into another permanent bin. Water would be mixed with the coffee in this bin. Then the mixture would be fed into a machine that removed the skins.
The container in the middle of this would only hold things for very short periods. It was used for transient storage only while processing was running. When the machines were off there was never anything in it. I imagine other assembly lines and processing streams have containers that serve the same purpose. In an electric circuit a capacitor roughly does this -- gather some amount of something from one end, at some point release it to the other end.
Is there a term for this kind of transient container in a processing stream?
It has an input. It has an output. The speed of input and output can each be controlled independently. You can close the output and let it fill up if you want, to be used shortly.