Mitchell foam quality

The gas volume fraction in a foam. Expressed as a percentage this fraction is sometimes referred to as the Mitchell foam quality . In three-phase systems, other measures are used. For example, when foams are formulated to contain solid particles as well, the slurry quality, Qs, which gives the volume fraction of gas plus solid, can be used Qs = (Vg + Vs)/(Vg + Vs + Vi), where Vg, Vs, and Vi denote the volumes of gas, solid, and liquid phases, respectively. 

Mist Drilling Fluid Mitchell Foam Quality Monodisperse... 

Foams are best defined by their quality, which is the percentage of gas contained within the foam. Mitchell foam quality, which is more wide-... 

Foam Quality. The gas volume fraction in a foam. Expressed as a percentage this is sometimes referred to as Mitchell foam quality. In three-phase systems other measures are used. 

Another foam quality that is not used as commonly as the Mitchell quality is slurry quality . Slurry quality (Qs), or total internal phase volume, is defined as the ratio of the volume of gas (VG) plus the volume of proppant (Fp) to the total slurry volume (VG + + fQ (3-5). 

Vp is the volume of proppant. The volume fraction of gas (VG) and liquid (Vp) does not change therefore, Mitchell s foam quality expression can be used to determine the volume fraction of the gas. 

Figure 10. Foam viscosity depends on percent internally dispersed gas (Mitchell quality). (Reproduced from ref. 363. U.S. Patent 3 937 283,1976.)...

A major factor that afreets foam qualify is the shear rate that is imposed upon the foam. In his Ph.D. dissertation, Mitchell (38) showed the relationship between viscosity, quality, and shear rate for Newtonian external foams (Figure 11). Two observations can be made from the diagram. The first is the absence of shear rate dependence on foams with qualities... 

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