In science, flow is the movement of matter or energy per unit time per unit area.
In hmolscience, flow can refer to a number of movement or energy characterizations; including: "psychological" flow, Gibbs energy flow, thermodynamic flow, or even the flow of human molecules in bulk, such as on a busy expressway, as studied in human chemistry. 
See main: Csíkszentmihályi flowIn psychodynamics, Csíkszentmihályi flow or simply “flow” is a state of focused, engaged, and optimal mental activity, quantified by energy and entropy measures, in which a sense of timelessness and outputs of great productivity emerge. 
“All energy flows according to the whims of the great magnet. What a fool I was to defy him.”— Hunter Thompson (1971), Fear and Loathing in Las Vegas (Ѻ); favorite author Patrick Fergus