Application of numerical modeling in the analysis of hydrometric structures in open water channels

Subject: the algorithms and software for numerical analysis of flow-measuring structures in open channels are considered. The actual accuracy of measurements and range of application of such structures are limited by the conditions of preliminary experimental studies. The empirical formulas given in literature are in most cases insufficient for correct estimate of the metrological characteristics reliability and the applicability limits of hydrometric structures. Research objectives: development of software package for the analysis of hydrometric structures which ensures an increase of measurement results reliability and expansion of the range of flow measurements in open channels of water management systems. Materials and methods: based on trial calculations, we have identified and analyzed the shortcomings of the known general software packages for fluid flow analysis in terms of calculation of water discharge characteristics of hydrometric structures. We have developed the numerical algorithms and modules of a specialized software package for analysis of hydrometric structures without the drawbacks inherent to universal software products. Results: the computer software package for analysis of hydrometric structures based on the numerical solution of the Navier-Stokes equations in a three-dimensional formulation was created and tested on several types of flow-measuring structures. For increasing accuracy of discharge calculation, the new program module for generation of the grid with hexoidal cells was developed. The individual boundary and initial conditions for different structures are prescribed depending on free-flow or variable backwater regime. All calculation procedures, from the input of initial data to the output of results of the analysis in text or graphical form, are performed automatically, without participation of the user. As an example, the software testing was performed on the Crump weir calculation and the results of the test are given. Conclusions: according to the test results, the error in calculating the discharge characteristics doesn’t exceed 2…4 % depending on the type of hydrometric structure, which meets the requirements of technological and commercial water accounting. Thus, the developed software package can be used to increase the accuracy and expand the range of measurements of existing hydrometric structures, develop new types of water accounting facilities and study in depth their operation under non-standard conditions.