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  2. Hydrodynamical helicity - Wikipedia

    en.wikipedia.org/wiki/Hydrodynamical_helicity

    Helicity is a pseudo-scalar quantity: it changes sign under change from a right-handed to a left-handed frame of reference; it can be considered as a measure of the handedness (or chirality) of the flow. Helicity is one of the four known integral invariants of the Euler equations; the other three are energy, momentum and angular momentum.

  3. Drainage equation - Wikipedia

    en.wikipedia.org/wiki/Drainage_equation

    the soil's hydraulic conductivity (Ka and Kb) by measurements; the depth of the bottom of the aquifer (Di) the design drain spacing (L) can be found from the equation in dependence of the drain depth (Dd) and drain radius (r). Drainage criteria

  4. Dilatancy (granular material) - Wikipedia

    en.wikipedia.org/wiki/Dilatancy_(granular_material)

    This phenomenon of soil behaviour can be included in the Hardening Soil model by means of a dilatancy cut-off. In order to specify this behaviour, the initial void ratio, e i n i t {\displaystyle e_{init}} , and the maximum void ratio, e m a x {\displaystyle e_{max}} , of the material must be entered as general parameters.

  5. Capillary number - Wikipedia

    en.wikipedia.org/wiki/Capillary_number

    Flow through the pores in an oil reservoir has capillary number values in the order of 10 −6, whereas flow of oil through an oil well drill pipe has a capillary number in the order of unity. [ 4 ] The capillary number plays a role in the dynamics of capillary flow ; in particular, it governs the dynamic contact angle of a flowing droplet at ...

  6. Hydraulic conductivity - Wikipedia

    en.wikipedia.org/wiki/Hydraulic_conductivity

    This procedure allows water to move through the soil under a steady state head condition while the volume of water flowing through the soil specimen is measured over a period of time. By knowing the volume Δ V of water measured in a time Δ t , over a specimen of length L and cross-sectional area A , as well as the head h , the hydraulic ...

  7. Relative permeability - Wikipedia

    en.wikipedia.org/wiki/Relative_permeability

    Based on data from special core analysis laboratory (SCAL) experiments, [2] simplified models of relative permeability as a function of saturation (e.g. water saturation) can be constructed. This article will focus on an oil-water system.

  8. Richards equation - Wikipedia

    en.wikipedia.org/wiki/Richards_equation

    The Richards equation represents the movement of water in unsaturated soils, and is attributed to Lorenzo A. Richards who published the equation in 1931. [1] It is a quasilinear partial differential equation; its analytical solution is often limited to specific initial and boundary conditions. [2]

  9. Water content - Wikipedia

    en.wikipedia.org/wiki/Water_content

    Water content or moisture content is the quantity of water contained in a material, such as soil (called soil moisture), rock, ceramics, crops, or wood. Water content is used in a wide range of scientific and technical areas, and is expressed as a ratio, which can range from 0 (completely dry) to the value of the materials' porosity at ...