Pumped Flow and Head with Previous Value

This model uses a simplistic approach to model a constant speed pump that lifts water through a pipe to an open reservoir as shown in the image below.

To account for friction losses, I use the empirical Hazen-Williams friction loss formula with the previous value of flow used as input. This model is a simplified approach that is adequate for systems with little change in total dynamic head over time. Any change to the boundary conditions (downstream water level, for example), will cause ripple effects that take multiple time steps to equalize.

For more dynamic systems, it is recommended that you use the Pumping Flow and Head Solver instead, which relies on a Script solver to calculate head and flow simultaneously.

See the comparison below of the outputs when using the Previous Value element vs. an iterative flow solver to calculate the minor and friction losses in the system.

Download the example model: