Dynamic Dispersivity and Methods of its Determination

Its value D is determined as summary value of effective diffusion coefficient and mechanical dispersion coefficient  

This parameter also depends on filtration and has different values along and across the direction of flow lines  

Hydrodynamic dispersion is a summary effect of two mixing processes whose relative contribution depends on the seepage velocity and groimd 

As a rule, exactly the dynamic dispersivity is the main characteristic of rock capability to mix and disperse water-dissolved components. Its significance in mass transfer is similar to the significance of hydraulic conductivity in hydrogeodynamics. 

As was shown above, the dispersivity value depends on its direction relative to flow lines, on ground rmiformity and isotropism. Crosswise horizontal dispersivity is studied much less than lengthwise one. Experiments show that it usually is by the order of magnitude lower than lengthwise dispersivity. Crosswise vertical dispersivity, as a rule, by 1 - 2 orders of magnitude smaller than crosswise horizontal dispersivity. In a medium with clearly expressed horizontal lamination the values of vertical dispersivity may be similar to the values of effective diffusion coefficient. 

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