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CFD Analysis of the Effects of Compound Downstream Slope on Flow Over the Spillway

Jahad Udai A., Chabuk Ali, Alabas Mohammed A., Mahmoud Ammar S., Al-Ansari Nadhir, Laue Jan

Journal of Ecological Engineering

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2023

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Vol. 24, nr 11

274--286

EN

The volume of the stilling basin can be reduced, energy can be dissipated, and floods can be contained with the help of spillways. The aim of this Computational Fluid Dynamics (CFD) study is to investigate how compound slopes change water flows through spillways. To measure turbulence, the Realizable k-ε model was used, and the multiphase volume of fluid (VOF) method was utilized to determine where air and water meet. Five models of spillways with different slopes (normal slope (MS1) = 30°, compound slope(MS2 and MS3) = 20°/39°, and compound slope (MS4 and MS5) = 39°/20°) were modelled and simulated using the ANSYS Fluent software to determine their flow characteristics. Numerical simulation results were compared to experimental results, and it was found that the CFD model captured the key flow aspects accurately. The numerical model carefully observes the several flow patterns (nappe, transition, and skimming) that emerged owing to variations in slope and geometry. When it comes to dissipating energy, models with a compound slope (39°/20°) do the best. When compared to the normal slope model (30°) with a step size of 10, the increase in energy dissipation is 14%. According to the findings, the TKE (turbulent kinetic energy) was elevated by the compound slope. The results of this research show that the spillway can be operated effectively and reliably under a wide range of flow conditions, fulfilling an important goal of the project.

2

Simplified Volume of Fluid Method (SVOF) for Two-Phase Flows

Marek M., Aniszewski W., Bogusławski A.

TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk

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2008

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Vol. 12, No 3-4

255-265

EN

The PLIC approach has been usually used in recent implementations of the VOF method i.e. the interphasal surface is approximated by a plane with an arbitrary orientation with respect to the computational cell. Although this method is accurate, it is rather difficult to implement, as a large number of orientations need to be taken into account and the calculation of volume fraction fluxes is not straightforward. A simpler approach to VOF – SLIC – requires much less effort from the programmer but the interface approximation by a plane parallel to the cell surfaces is too crude and the results are not satisfactory. The method presented in the article may be considered as an intermediate approach between PLIC and SLIC – fluxes are computed directly only for the interface’s special orientations and linear interpolation is used for calculation of the fluxes for the remaining cases. Some classical tests of the proposed method are performed and an example of a broken dam problem simulation is presented.

3

Modelling of the free surface flow with high resolution schemes

Wacławczyk T., Koronowicz T.

Inżynieria Chemiczna i Procesowa

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2006

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T. 27, z. 3/1

783-802

EN

The paper concerns modelling of the free surface flow with the volume of fluid (VOF) method. The original contribution of this work is a detailed comparison of two high-resolution schemes, taking into consideration their ability to capture the interface subjected to strong deformation. Verification and validation of the schemes is performed in three test cases: advection of the bubble in a uniform velocity field, convection of the bubble including effects of surface tension and breaking of the water wave in the gravitational field.

PL

Poniższa praca dotyczy modelowania przepływów ze swobodną powierzchnią metodą Volume of Fluid (VOF). Oryginalnym wkładem jest szczegółowe porównanie dwóch schematów o wysokiej rozdzielczości ze względu na ich właściwości podczas rekonstrukcji powierzchni rozdziału. Schematy zweryfikowano w trzech przypadkach testowych: swobodnego unoszenia pęcherzyka w jednorodnym polu prędkości, konwekcji pęcherzyka z uwzględnieniem efektów napięcia powierzchniowego oraz załamania fali w polu grawitacyjnym.

4

Simulations of the water freezing process: numerical benchmarks

Michałek T., Kowalewski T. A.

TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk

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2003

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Vol. 7, No 3

389-408

EN

Three numerical benchmarks concerning the freezing of water in small enclosures are analysed using the commercial FLUENT code. The first case is a steady-state natural convection in a differentially heated cavity for temperatures near the freezing point. In the second case, the freezing of water in a differentially heated cavity is simulated. The third case describes a simulation of freezing water in the presence of forced convection and a free surface flow. Two finite-differences numerical codes are used to verify results of the FLUENT simulations for the natural convection and solidification in the differentially heated cavity. It is found that the simulation of water solidification requires very fine meshes and short time steps, extending the computational time to the extreme.