Experimental and Numerical Analysis of Flow around a Circular Bridge Pier

Year 2018, Volume: 21 Issue: 1, 137 - 147, 31.03.2018

N. Göksu Soydan Oğuz Şimşek M. Sami Aköz

https://doi.org/10.2339/politeknik.389584

Cited By: 3

Abstract

The turbulent flow field around a circular pier is
complex due to separation and generation of multiple vortices in different
structures. This topic has a great interest in engineering applications for the
design of the bridges over water. In this study, the velocity field of flow
around a circular pier is measured using Laser Doppler Anemometry (LDA). The
Basic equations of the problem are solved by ANSYS-Fluent program package based
on finite volume method for the flow case having the same experimental conditions.
In the numerical simulations, Standard k-ε,
Renormalization Group k-ε and
Realizable k-ε turbulence closure
model are used for the simulation of turbulence, and the flow profile is
computed using Volume of Fluid method. Grid Convergence Index (GCI) is
performed to examine the effect of the selected grid structure on the numerical
results. The computed results for velocities and free surface profiles are
compared with measured data. The comparisons of the experimental and numerical
results show that Realizable k-ε is
more successful turbulence model among the other models in predicting the
velocity field and free surface profiles.

Keywords

Bridge pier, LDA, RANS, turbulence modeling, VOF

Köprü Ayağı Etrafındaki Türbülanslı Akımın Sayısal ve Deneysel Analizi

Abstract

Dairesel bir köprü ayağı
etrafındaki türbülanslı akış alanı, çoklu girdapların oluşumu nedeniyle
karmaşık bir yapıya sahiptir. Köprü ayağı etrafında meydana gelen bu karmaşık
akım yapısının belirlenmesi, bu tür yapıların tasarımı açısından önem kazanmaktadır.
Bu çalışmada köprü ayağı etrafındaki üç boyutlu türbülanslı akımın hız alanı
laboratuvar ortamında Lazer Doppler Anemometresi (LDA) ile ölçülmüş ve deney
ile aynı koşullardaki akım için temel denklemler, sonlu hacimler yöntemine
dayalı ANSYS-Fluent paket programı ile sayısal olarak çözülmüştür. Sayısal
modellemede, Standard k-ε,
Renormalization Group k-ε ve
Realizable k-ε türbülans modeli
kullanılmış ve serbest su yüzü profili Akışkan Hacimleri Yöntemi ile
hesaplanmıştır. Seçilen ağ yapısının sayısal sonuçlara olan etkisini incelemek
için Ağ Yakınsama İndeksi (GCI) kullanılmıştır. Sayısal sonuçlardan elde edilen
hız alanı ve su yüzü profilleri deneysel ölçümlerle karşılaştırılmış,
Realizable k-ε türbülans modelinin
köprü ayağı etrafındaki akım alanını belirlemede diğer modellere göre daha
başarılı olduğu tespit edilmiştir. 

Keywords

Köprü ayağı, LDA, RANS, türbülans modellemesi, VOF

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