Dispersion coefficient
General definition of dispersion coefficient (liquid phase)
where
|
θ |
water content [L3/L3] |
|
Dw |
dispersion coefficient [L2/T] |
|
Dw |
molecular diffusion coefficient in free water [L2/T] |
|
DL |
longitudinal dispersivity [L] |
|
q |
volumetric flux density [L/T] |
|
τw |
tortuosity factor in water [-] |
General definition of diffusion coefficient (gas phase)
where
|
av |
gas content [L3/L3] |
|
Dg |
gas diffusion coefficient [L2/T] |
|
Dg |
molecular diffusion coefficient in a free gas phase [L2/T] |
|
τg |
tortuosity factor in gas phase [-] |
Tortuosity models
Millington and Quirk model [Millington and Quirk, 1991]
where
|
τw |
tortuosity factor in water [-] |
|
τg |
tortuosity factor in the gas phase [-] |
|
θ |
water content [L3/L3] |
|
θs |
saturated water content [L3/L3] |
|
av |
gas content [L3/L3] |
Moldrup [Moldrup et al., 1997; Moldrup et al., 2000]
where
|
τw |
tortuosity factor in water [-] |
|
τg |
tortuosity factor in the gas phase [-] |
|
θ |
water content [L3/L3] |
|
θs |
saturated water content [L3/L3] |
|
av |
gas content [L3/L3] |