Estimation of open channel flow parameters by using optimization techniques

  Ebissa G. K,  Dr. K. S. Hari Prasad

Open channel flow parameter estimation is an inverse problem, which involves the prediction of a function within a domain, given an error criterion with respect to a set of observed data. Various numerical methods have been developed to estimate open channel flow parameters. For this study, Genetic Algorithm optimization technique is selected. Because of its inherent characteristics, Genetic Algorithm optimization technique avoids the subjectivity, long computation time and ill-posedness often associated with conventional optimization techniques. The present study involves estimation of open channel flow parameters having different bed materials invoking data of Gradual Varied Flow (GVF). Use of GVF data facilitates estimation of flow parameters. The necessary data base was generated by conducting laboratory experiments in Hydraulics Lab of civil Engineering at IIT Roorkee. In the present study, the efficacy of the Genetic Algorithm (GA) optimization technique is assessed in estimation of open channel flow parameters from the collected experimental data. Computer codes are developed to obtain optimal flow parameters Optimization Technique. Applicability, Adequacy & robustness of the developed code are tested using sets of theoretical data generated by experimental work. Estimation of Manning’s Roughness coefficient from the collected experimental work data by using Manning’s equation & GVF equation were made. The model is designed to arrive at such values of the decision variables that permit minimized mismatch between the observed & the computed GVF profiles. A simulation model was developed to compute GVF depths at preselected discrete sections for given downstream head and discharge rate. This model is linked to an optimizer to estimate optimal value of decision variables. The proposed model is employed to a set of laboratory data for three bed materials (i.e, d50=20mm, d50=6mm and lined concrete). Application of proposed model reveals that optimal value of fitting parameter ranges from 1.42 to 1.48 as the material gets finer. This value differs from the currently documented value i.e. 1.5. The optimal estimates of Manning’s n of three different bed conditions of experimental channel appear to be higher than the corresponding reported /Strickler’s’ estimates. Key Words:- Open channel flow parameters, GVF, parameter estimation, optimization techniques, Manning’s roughness coefficient.

Keywords- Open channel flow parameters, GVF, parameter estimation, optimization techniques, Manning’s roughness coefficient.

Unique Identification Number - IJEDR1702179
Page Number(s) - 1049-1073
Pubished in - Volume 5 | Issue 2 | May 2017
DOI (Digital Object Identifier) -    http://www.dx.doi.org/10.5281/zenodo.583720
Publisher - IJEDR (ISSN - 2321-9939)

  Ebissa G. K,  Dr. K. S. Hari Prasad,   "Estimation of open channel flow parameters by using optimization techniques", International Journal of Engineering Development and Research (IJEDR), ISSN:2321-9939, Volume.5, Issue 2, pp.1049-1073, May 2017, Available at :http://www.ijedr.org/papers/IJEDR1702179.pdf