A flownet is a grid obtained by drawing a series of streamlines and equipotential lines are known as a flow net.Equi-Potential Line is an imaginary line in a field of flow such that the total head is the same for all points on the line, and therefore the direction of flow is perpendicular to the line at all points.

Construction of a flownet is often used for solving groundwater flow problems where the geometry makes analytical solutions impractical.

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The method is often used in civil engineering, hydrogeology or soil mechanics as the first check for problems of flow under hydraulic structures like dams or sheet pile walls. As such, a grid obtained by drawing a series of equipotential lines is called a flownet. The flownet is an important tool in analysing two-dimensional irrotational flow problems. Flow net technique is a graphical representation method.

Basic Method Of Calculating Flownet-

The method consists of filling the flow area with a stream and equipotential lines, which are everywhere perpendicular to each other, making a curvilinear grid. Typically there are two surfaces (boundaries) which are at constant values of potential or hydraulic head (upstream and downstream ends), and the other surfaces are no-flow boundaries (i.e., impermeable; for example the bottom of the dam and the top of an impermeable bedrock layer), which define the sides of the outermost stream tubes (see figure 1 for a stereotypical flownet example).