IMPROVED LUMPING FRICTION MODEL FOR LIQUID PIPE FLOW

Normally, during one-dimensional pipe flow, the friction terms are calculated with the use of
a numerical method (for example MOC – method of characteristics) at every computational
node along the pipe and at every time step. This procedure tends to increase the computational
effort greatly. A considerable increase in computational speed can be archived by
calculating the frequency-dependent friction at the end of the pipe only. To avoid possible
problems (no damping at closed walls, underestimate damping on high impedance components)
the frequency-dependent friction term is calculated from the flow waves. The lumping
friction model in this work is based on a modificated Schohl convolution integral solution. In
addition, the work examined the impact of using of simplified effective weighting function on
the obtained results of numerical simulations. The modified method in conjunction with the
use of simplified weighting function allow determination of real-time estimate of the basic
parameters representing the fluid flow in complex hydraulic systems, water supply, etc.