Volumetric vapour content

The quantity e is called the volumetric vapour content. This is to be distinguished from the volumetric quality... 

The volumetric quality e and the vapour content coincide when the slip factor is equal to one, i.e. when wG = wL, which then gives... 

Accurate calculations are only possible here, if a reliable relationship for the volumetric vapour content is available. 

If the slip factor can be set to s = 1, (homogeneous flow), then, according to (4.114), the volumetric vapour content will be... 

With the assumption of equal liquid and vapour velocities, the volumetric vapour content is obtained from (4.126) and with that the density of the homogeneous flow is... 

Figure 1 shows the identified water diffusivity as functions of volumetric water content. Water diffusivity is U-shaped. This is considered that water moves in the vapour phase at the dry condition and does in the liquid phase at the wet condition. 

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