13.2.2 Relative Conductivity and Phreatic Storativity

Next: 13.2.3 Turbulence Up: 13.2 Detailed Groundwater Flow Previous: 13.2.1 Saturated Conductivity and Contents Index

13.2.2 Relative Conductivity and Phreatic Storativity

DIANA determines pressure head dependent relative conductivity and storage by linear interpolation in diagrams. There are two possibilities for input of such diagrams. First it is possible to describe a direct relationship between relative conductivity and pressure.

Conductivity (syntax)

$\begin{figure}\centering \begin{tabbing} \texttt{'MATERI'} \\ [-1.0ex] \rule{14... ...xtit{hn}}$_{r}\,$ \texttt{\textit{kn}}$_{r}\,${]} \end{tabbing} \end{figure}$

CONPRS: specifies a pressure-conductivity diagram: h1 ...hn are the pressure heads $\phi_{{\mathrm{p},i=1,n}}^{}$ , and k1 ...kn are the corresponding relative conductivities k_{r, i=1, n} .

Because in practice, the relative conductivity is often related to the degree of saturation and the saturation is on turn related to the pressure head, the nonlinear conductivity may also be specified via saturation.

Saturation (syntax)

$\begin{figure}\centering \begin{tabbing} \texttt{'MATERI'} \\ [-1.0ex] \rule{14... ...xtit{hn}}$_{r}\,$ \texttt{\textit{sn}}$_{r}\,${]} \end{tabbing} \end{figure}$

CONSAT: specifies a saturation-conductivity diagram: s1 ...sn are the degrees of saturation S_{i=1, n}, ( 0 $\leq$ S_r $\leq$ 1 )and kr1 ...krn are the corresponding relative conductivities k_{r, i=1, n} . ( 0 < k_r $\leq$ 1 )
SATURA: specifies a pressure-saturation diagram: h1 ...hn are the pressure heads $\phi_{{\mathrm{p},{i=1,n}}}^{}$ , and s1 ...sn are the corresponding degrees of saturation S_{i=1, n} . ( 0 $\leq$ S $\leq$ 1 )

In case of a transient analysis , a direct relationship between capacitance and pressure head may be defined:

Capacitance (syntax)

$\begin{figure}\centering \begin{tabbing} \texttt{'MATERI'} \\ [-1.0ex] \rule{14... ...xtit{hn}}$_{r}\,$ \texttt{\textit{cn}}$_{r}\,${]} \end{tabbing} \end{figure}$

CAPPRS: specifies a pressure-capacitance diagram: h1 ...hn are the pressure heads $\phi_{{\mathrm{p},i=1,n}}^{}$ , and c1 ...cn are the corresponding capacitances c_{i=1, n} .

Instead, it is also possible to derive the capacitance from the relation between degree of saturation and pressure (13.9). In this derivation the effective porosity is used.

Porosity (syntax)

$\begin{figure}\centering \begin{tabbing} \texttt{'MATERI'} \\ [-1.0ex] \rule{14... ...x] \>\>\texttt{POROSI}\>\texttt{\textit{n}}$_{r}\,$ \end{tabbing} \end{figure}$

SATURA: specifies a pressure-saturation diagram: h1 ...hn are the pressure heads $\phi_{{\mathrm{p},i=1,n}}^{}$ (increasing values), and s1 ...sn are the corresponding degrees of saturation S_{r, i=1, n} . ( 0 $\leq$ S_r $\leq$ 1 )
POROSI: n is the value of the effective porosity n . ( 0 $\leq$ n $\leq$ 1 )

(file.dat)

'MATERI'
  1   CONPRS    -1.6.E2   1.E-5
                -0.25     0.012
                -0.05     0.65
                -0.01     0.987
                 0.       1.
                 100.00   1.
      POROSI     0.2
      SATURA    -1.6E2    0.03
                -25.00    0.06
                -0.60     0.30
                 0.       1.0
                 100.00   1.0

In the above example, the CONPRS record specifies the relation between pressure and relative conductivity: the first value on each line is the pressure, the second value the conductivity. The SATURA record specifies the relation between saturation and pressure: the first value on each line is the pressure, the second value the saturation.

Next: 13.2.3 Turbulence Up: 13.2 Detailed Groundwater Flow Previous: 13.2.1 Saturated Conductivity and Contents Index

DIANA-9.3 User's Manual - Material Library
First ed.

Copyright (c) 2008 by TNO DIANA BV.