<< Click to Display Table of Contents >> Navigation:  Wadiso 6 User Guide > Time/Water quality simulation > Time/WQ techniques and general concepts > Time simulation hydraulic model

EPANet’s hydraulic simulation model computes heads at nodes and flows through links, for a fixed set of reservoir levels, tank levels, and water demands, over a succession of points in time. From one time step to the next, reservoir levels and node demands are updated according to their prescribed time patterns, while tank levels are updated using the current flow solution. The solution for heads and flows at a particular point in time involves simultaneously solving the conservation of flow equation for each node, and the head loss relationship across each link in the network. This process, known as “hydraulically balancing” the network, requires using an iterative technique to solve the nonlinear equations involved. EPANet employs the “Gradient Algorithm” for this purpose. Further details can be provided upon request.

 

The hydraulic time step used for extended period simulation (EPS) can be set by the user. A typical value is 1 hour. Shorter time steps than normal will occur automatically whenever one of the following events occurs:

•the next output reporting time step occurs

•the next time pattern step occurs

•a tank becomes empty or full

•a simple control or rule-based control is activated.