Maintain slurry temperature between 85–90°C for most of the brew.
Bulk flow (advection) moves solubles away from the grounds; diffusion moves them from inside particles. Effective brewing balances both — sufficient flow to remove extracted solubles so concentration gradients drive further extraction, but not so fast that contact time is too short. The Physics Of Filter Coffee Pdf
Excessive turbulence can force water to find paths of least resistance through the bed. This is called Channeling . When channeling occurs, water bypasses most of the coffee (under-extraction) and over-extracts the specific channel walls (bitterness). Maintain slurry temperature between 85–90°C for most of