Can you give us more details on the linear programing method used by IRRICAD.?
The help tell us that:
LP (Linear Programming) is a method that attempts to select pipe diameters so that the required pressures of the zone outlets are met.
To size pipes using LP Design:
1. Select Design|Zone Design|LP Design or Design|Mainline Design|LP Design.
2. IRRICAD will attempt to size any Computer Sized pipes in the design.
Note: LP sizing can not be used for looped systems or for mainline design in systems with multiple water supplies.
Pipe sizing is carried out using a Linear Programming (LP) optimization in conjunction with hydraulic grade lines method. Pipe sizes are optimized based on the annualized cost of pipes and energy. Pipe networks are solved using a combination Linear and Newton Raphson algorithm. Pipe friction is calculated using Hazen-Williams for mainlines and submains with Darcy-Weisbach or Diskin for driptape calculations.
The calculations have been field-checked by numerous irrigation design companies in the US for technical accuracy and has been found to give excellent results.
Briefly the method used for Mainline is:-
a) For each unique flow condition (these are determined by the user specifying which outflows or zones operate together) IRRICAD sizes pipes using our own linear programming method. This method optimizes pipe sizes economically (by comparing capital costs on an annual basis with running costs) while satisfying velocity, pressure and practical requirements.
b) The final pipe size for each link is determined by simply selecting the maximum size from the unique flow conditions (as in a) above).
c) The system is now analyzed with the selected pipe sizes.
