Steady state apparent age

The time required for achieving the steady-state concentration depends on the value of Cq and the precision required. Take the required precision to be 1% relative. If Cq < pa /D, then the condition of t —> oo is roughly satisfied when Dtja > 2. If Co > pg /(3D), then steady state is reached when Df/g is greater than (4/7i )ln[100 8Q/7i —96/ti ], where Q=Co/[pg /(3D)]. The steady-state volume-average concentration corresponds to a steady-state apparent age of... 

Hence, every point in the concentration profile corresponds to a steady-state apparent age of... 

At the center, the steady-state apparent age is tss = a /(2D), 1.5 times the volume-averaged apparent age of the whole grain. 

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