Residual water content
is the "adjusting screw" that defines the overall economics of a project.
where [[theta].sub.w] is the volumetric water content; [[theta].sub.s] is the saturated volumetric water content; h is the matric suction; and [a.sub.f], [b.sub.f], [c.sub.f], and [h.sub.r] are fitting coefficients, which are primarily a function of the air entry value, rate of water extraction from the soil, residual water content
, and suction at which the residual water content
where [theta] represents the volumetric water content function, [[theta].sub.r] represents the residual water content
and [[theta].sub.s] represents the saturated water content.
Nano carbon VG content (%) [theta]s [theta]r [alpha] n [R.sup.2] ([cm.sup.3] ([cm.sup.3] ([cm.sup.-1]) [cm.sup.-3]) [cm.sup.-3]) 0 0.4907 0.0878 0.01896 1.772 0.997 0.1 0.5088 0.0990 0.01910 1.668 0.997 0.5 0.5210 0.0917 0.02588 1.539 0.992 0.7 0.5283 0.0940 0.02279 1.527 0.997 1 0.5375 0.0983 0.02779 1.509 0.993 Nano carbon BC content (%) [alpha] n [R.sup.2] ([cm.sup.-1]) 0 0.02792 0.658 0.996 0.1 0.02859 0.573 0.994 0.5 0.03352 0.499 0.985 0.7 0.03219 0.471 0.992 1 0.03539 0.475 0.986 Note: [R.sup.2] is the coefficient of determination for the fit of the VG or BC model to the experimental data; [theta]s, saturated water content; [theta]r, residual water content
; [alpha], empirical parameter; n, pore-size distribution parameter Table 5.
Valiantzas  combined Brooks-Corey and Van Genuchten closed-form models improving prediction of conductivity values near the residual water content
2008, 2012); C is the residual water content
, [A.sub.1] and [A.sub.2] are the water contents of the textural and structural pore spaces at saturation, and [P.sub.1] and [P.sub.2] are applied air pressures characteristic for emptying the textural and structural pore spaces, respectively.
Abbreviations: Se = the effective degree of saturation, th = the volumetric water content, thr = residual water content
, ths = saturated volumetric water content, thm, thim= mobile and immobile water content, respectively, thFC = volumetric water content of soil at field capacity (cm3 cm-3); thWP = volumetric water content of soil at wilting point (cm3 cm-3).
Commercially available lubricating oils are delivered by most manufacturers with low residual water content
Before flooding, measurements of [theta] and h were made in order to estimate residual water content
Or from measured low water content under dry conditions for the soil, which is also one of the model parameters.
where [theta]s is the saturated water content ([m.sup.3][m.sup.3]), Or is the residual water content
([m.sup.3][m.sup.-3]), and n is an adjustable parameter that describes the shape of the curve.
where [[theta].sub.s] is the saturated water content ([L.sup.3]/[L.sup.3]), [[theta].sub.r] is the residual water content
([L.sup.3]/[L.sup.3]), 1/[h.sub.e] is a scaling parameter, defined as the inflection point of the curve where [h.sub.e](L) is often described as the air entry parameter, n is a slope parameter, and m is a symmetry parameter with m = 1-[2/n], often referred to as the Burdine restriction (Burdine 1953).
The parameters that were directly calibrated by fitting the model's prediction to observed data were: boundary pressure potential, boundary water content, residual water content
, pore size distribution index in micropores, boundary hydraulic conductivity, tortuosity factors in macropores and micropores, dispersivity, and mixing-depth.