where qs is the average gas density at certain height, d is the length
of shaft horizontal section, k1 is a constant (0.28) obtained
experimentally, z is the height, and g is the gravity acceleration.
In a high shaft, if L=d 1, Cooper modified Zukoski’s turbulent
model with a universal K and compared the solutions with previously
published data from salt-water/fresh-water and heavy-gas/
light-gas experiments. The corrected turbulent mixing model is
expressed as: