Optimal Channel Cross Section with Composite Roughness
Publication: Journal of Irrigation and Drainage Engineering
Volume 126, Issue 1
Abstract
For channels with composite roughness, an equivalent uniform roughness coefficient and flow geometric elements are used in an optimal design method using the Manning equation. The optimal design problems are formulated in a nonlinear optimization framework with the objective function being a cost function per unit length of the canal. Constraints are the Manning equation, positive values for design variables, and specified values of side slopes or top width. The constrained problem is transformed into an unconstrained problem using the Lagrangian multipliers. To obtain an optimal solution for the resulting unconstrained problem, the first-order necessary conditions for optima are applied. The resulting simultaneous nonlinear equations are solved using the computational methodology developed. This technique is applied to illustrative numerical examples. The evaluations establish the potential applicability of the developed computational methodology for optimal design of open channel cross sections with composite roughness.
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Information & Authors
Information
Published In
Journal of Irrigation and Drainage Engineering
Volume 126 • Issue 1 • January 2000
Pages: 68 - 72
History
Received: Mar 25, 1998
Published online: Jan 1, 2000
Published in print: Jan 2000
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