Flownet

Also called potential network or potential network - - With a flow network is graphically represents a seepage in soil with flow lines and equipotential lines in two dimensions dar. flow lines and equipotential lines, both of which can be curved, intersecting at right angles to each other always. The even flow net or potential route network called network of tiny rectangular, curvilinear bounded square -like loops which can gradually change its size. A decreasing mesh size indicates an increase of the seepage velocity.

In the flow network, the potential lines connecting the points with the same potential, ie in this case the same piezometric head. The power lines represent the direction of flow, the flow filaments. In each stream tube, the water percolating through the same. The potential lines are to each other the same distance as long as the permeability is the same. At a lower permeability of the spacing of the potential lines is decreased, and vice versa. The potential lines intersect not only the flow lines at right angles, they are also perpendicular to impervious boundaries.

A flow network is used to calculate a seepage through a dam, a dike along an embankment or under a weir, by an excavation or groundwater flow to a well back. This gives the result, the percolating water volume and the pore water pressures, the piezometric heads at various points, and it can calculate the sole water pressure. The hydraulic gradient is the potential difference between two potential lines with respect to their spacing. It must not be too large in leaked floor, as there may be slope failure or other constructional damage otherwise. Can reduce the gradient by extending the leakage path and thus increases the distance between the potential lines.

To draw a flow network, you need some skill. The potentials, however, can be calculated quite well with the finite element method. The calculation is based on the potential theory, the Darcy's law and Laplace's equation. The potential Linen and the gradient can be well calculated and displayed. The determination of streamlines is a much larger computational technical problem.

The construction of flow nets goes back to Philipp Forchheimer.

Literature / Sources

• Henner Turk: Statics in earthworks. 3rd edition 1999, ISBN 978-3-433-01791-3