PERFORMANCE EVALUATION OF EXPLICIT FRICTION FACTOR RELATIONS WHEN ANALYSING WATER DISTRIBUTION NETWORKS.pptx

PERFORMANCE EVALUATION OF DISTRIBUTION NETWORKS

1. PERFORMANCE EVALUATION OF EXPLICIT FRICTION FACTOR RELATIONS WHEN ANALYSING WATER DISTRIBUTION NETWORKS USING h-BASED METHODS

2. PRESENTATION OUTLINE Background of the study Statement of the problem Aims and objectives Significance of the study Literature review Methodology Results

3. BACKGROUND OF STUDY Water is vital for every form of life. Providing water has been an important issue in history. Water supply in modern times is done using systems that comprise of a water source, a treatment point and a distribution network. Hydraulic calculations of flow in WDNs is not easy due to the presence of loops and is usually solved with computer programs (spreadsheet solvers). Determining friction factor is a key step in hydraulic analysis of flow in pipes. Different equations exist for computing friction factor. The choice of friction factor equation used may have an impact on the result and duration of the analysis.

4. STATEMENT OF THE PROBLEM Several explicit friction factor relations have been developed as alternatives to the Colebrook equation which is implicit in nature. The accuracy of these relations are usually compared with that of the Colebrook equation but there is little knowledge on the efficiency of these relations in analyzing WDNs, especially pertaining to computational time. Previous work ranked the performance of the relations on number of iterations, a basis which might be erroneous.

5. AIMS AND OBJECTIVES OF THE STUDY AIM To evaluate the performance of explicit friction factor relations when used in analyzing WDNs. OBJECTIVES To solve WDN problems using explicit friction factor relations. To determine the number of iterations and computational time of the relations in solving the WDN problems. To ascertain the best performing relation(s) for analyzing WDNs.

6. SIGNIFICANCE OF THE STUDY There is a need for water utilities to improve explanations of the movement of water through their WDNs. Better understanding of network behavior will lead to better management of WDNs. Efficient computation of friction factor in WDN analysis is significant in understanding and managing pipe networks.

7. LITERATURE REVIEW WDN WDNs are structures that collects, treats, stores, and distributes water between water sources and water demands. They are designated with links as pipes and nodes as connections between pipes, hydraulic control elements, demands, and sources. They can be arranged in: Grid layout Ring Layout Radial Layout, or Dead End Layout The behavior of a WDN is governed by: Flow relationship in pipes and hydraulic control element Demands, and Network layout The network quality affects the level of water supply.

8. LITERATURE REVIEW (CONTINUED) FRICTION FACTOR It is a dimensionless factor that depends on V, d, ρ , μ and ϵ . ϵ is neglected for smooth pipes and laminar flow. For turbulent flow, the resistance to flow follows D-W equation. The D-W friction factor depends on the relative roughness of the pipe. The D-W can be calculated by: Graphical solutions Colebrook equation Explicit friction factor relations Explicit relations have been studied to determine their accuracy and complexity ( Offor and Alabi , 2016).

9. LITERATURE REVIEW (CONTINUED) Pimenta et al (2018) analyzed 29 friction factor relations in comparison to the C-W equation in terms of relative error and performance index Muzzo et al (2019) compared 30 friction factor relations in terms of accuracy and computational time to find the relations with sufficient suitable balance Minhoni et al (2020) compared 6 friction factor relations based on relative error

10. LITERATURE REVIEW (CONTINUED) PREVIOUS WORK ON EVALUATING FRICTION FACTOR RELATIONS IN ANALYZING WDNs Niazkar and Talebbeydokhti (2019) evaluated the performance of explicit friction factor relations in the analysis of WDNs. They ranked the performance of the friction factor relations on the basis of accuracy and the number of iterations taken to converge.

11. METHODOLOGY MATERIALS: Three pipe networks were obtained from literature. 27 friction factor relations were also obtained from literature. MATLAB (2015 version): Was used as the simulation environment for coding and running the analysis of the WDNs. Excel: Was used as database for storing pipe properties and information for the analysis, and for displaying the output of the analysis such as head loss, flowrate, number of iterations, and computational time. METHODS: Gradient algorithm method The needed information was called from Excel into MATLAB. The gradient algorithm method was coded in MATLAB for the analysis. Number of iterations and computation time were noted at the end of the analysis.

12. RESULTS

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18. CONCLUSION The number of iterations is not a suitable criteria for ranking the performance of the friction factor relations The relations which converged faster to the solution are the Offor & Alabi , Fang et al, Niazkar -a, Swamee & Swamee , Li et al, and Romeo et al relations.

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