This is a more detailed model for the pipe that mostly can be used for proper modelling of the penstock or other conduits.
The model could include the elastic walls and compressible water and use discretization method based on Kurganov-Petrova central upwind scheme (KP). The geometry of the penstock is shown in the figure below:
Conservation laws are usually solved by the finite-volume methods.
With the finite-volume method, we divide the grid into small control
volumes or control cells and then apply the conservation laws.
Here the pipe is divided in N
segments, with input and
output pressure as a boundary conditions.
The given cell is denoted by j
, i.e., it is the j
th cell.
Cell average is calculated at the center of the cell and U
denotes the
average values of the conserved variables. The left and the right interfaces of the
cell are denoted by j-1/2
and j+1/2
respectively.
At each cell interface, the right(+)/left(-) point values are reconstructed.
The letter a
denotes the right and the left sided local speeds of propagation
at the left/right interface of the cell.
In order to determine the fluxes at the cell interface H
and the
source term S
, the KP scheme is used, which is a second order scheme that is well balanced.
More info about the KP pipe model can be found in can be found in [Vytvytskyi2017].