TM 5-818-5/AFM 88-5, Chap 6/NAVFAC P-418
Since the permeability in fluid flow is analogous to the
flow net constructed using an electrical analogy model
reciprocal of the specific resistance for geometrically
may be analyzed in the same manner as one con-
similar mediums, the shape factors for Darcy's law and
structed as in paragraph 4-3.
Ohm's law are the same.
e. Equipment for conducting three-dimensional
d. A two-dimensional flow net can be constructed
electrical analogy model studies is available at the
using a scale model of the flow and drainage system
WES. The equipment consists basically of a large
made of a conductive material representing the porous
plexiglass tank filled with diluted copper sulfate solu-
media (graphite-treated paper or an electrolytic solu-
tion and having a calibrated, elevated carrier assembly
tion), copper or silver strips for source of seepage and
for the accurate positioning of a point electrode probe
drainage, and nonconductive material representing
anywhere in the fluid medium. A prototype is simu-
impervious flow boundaries. The electrical circuit con-
lated by fabricating appropriately shaped and sealed
sists of a potential applied across the model and a
source and sink configurations and applying an elec-
Wheat&one bridge to control intermediate potentials
trical potential across them. The model is particularly
on the model (fig. 4-29). The flow net is constructed by
useful for analyzing complex boundary conditions that
tracing lines of constant potential on the model, thus
cannot be readily analyzed by two-dimensional tech-
establishing the flow-net equipotential lines after
niques.
which the flow lines are easily added graphically. A
(Fruco & Associates. Inc.)
U.S. Army Corps of Engineers
Figure 4-29. Diagrammatic layout of electrical analogy model.
4-33
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