is the slower process where molecules move from high-concentration areas (the bean) to low-concentration areas (the water). The "Avalanche Effect"
Most specialty coffee guides treat coffee particles as spheres of radius ( r ). A physics PDF would show that the characteristic time for extraction is ( \tau \approx r^2 / D ). This explains why grinding finer (reducing ( r )) exponentially speeds up extraction. The Physics Of Filter Coffee Pdf
– often summarized in the Coffee ad Astra blog (especially the post "A comprehensive guide to filter coffee brewing physics" ). You can save that page as a PDF yourself. is the slower process where molecules move from
[ Q_{\text{paper}} = \frac{\pi \Delta P r^4}{8 \mu L_{\text{paper}}} ] This explains why grinding finer (reducing ( r
For further reading, look up the following seminal papers:
As water penetrates the pores, ( \theta ) decreases, and the coffee becomes fully wetted. Without proper wetting, channeling occurs—water finds preferred paths, leaving dry coffee behind. A good physics PDF would explain how to calculate the ((Ca = \mu v / \gamma)) to ensure uniform bed saturation.