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Numerical Investigations of Scale Effects on Local Scour Around a Bridge Pier

Title: Numerical Investigations of Scale Effects on Local Scour Around a Bridge Pier.
Name(s): Yang, Qiping, author
Huang, Wenrui, professor directing thesis
Abdullah, Makola, committee member
Yazdani, Nur, committee member
Department of Civil and Environmental Engineering, degree granting department
Florida State University, degree granting institution
Type of Resource: text
Genre: Text
Issuance: monographic
Date Issued: 2005
Publisher: Florida State University
Place of Publication: Tallahassee, Florida
Physical Form: computer
online resource
Extent: 1 online resource
Language(s): English
Abstract/Description: Local scour around a bridge pier (a cylinder) is a problem of much concern to hydraulic engineers. This is a complex phenomenon resulting from the interaction of the three-dimensional turbulent flow field around the cylinder and the mobile channel bed. Under-prediction of scour depth can lead to costly bridge failures, while over-prediction can result in millions of dollars in unnecessary construction costs. Therefore, the knowledge of the anticipated maximum scour depth is essential for a proper design of the foundation of the bridge piers. Local scours around bridge piers have resulted in more bridge failures than all other causes in recent history. Local pier scour has been a popular topic of study by many laboratory researchers. The scour prediction methods developed in the laboratories and the scour equations based on laboratory data did not always produce reasonable results for field conditions. Recent research indicates that laboratory investigations often oversimplify or ignore many of the complexities of the flow fields around the bridge piers. The physical scales, the fluid properties and the boundary conditions in the small-scale models (the laboratory conditions) should be derived from the large-scale prototype (the field conditions) according to the Hydraulic Similitude Laws. Geometric similarity is usually required for all models, Reynolds number similarity for models involving flow around bodies and Froude number similarity for models involving free-surface flows. In fact, it is not practical for a physical model of local scour around a bridge pier to satisfy all these similarities. However, unlike a physical model, which suffers from scale effects, the CFD model employs the actual dimensions and operating conditions to calculate turbulent velocity and sediment scour. This thesis 1) verified the capabilities of the 3-D computational fluid dynamics (CFD) software package, FLUENT, to simulate local scour around a bridge pier by applying the numerical model to the experimental conditions and comparing the computed results with their laboratory data; 2) conducted the numerical simulations to compare turbulent flow characteristics between small-scale and large-scale local scour around a bridge pier according to Froude similitude by using the computational fluid dynamics software package, FLUENT; 3) compared and analyzed the differences of the simulation results between the small-scale and large-scale models; and 4) concluded that Reynolds number would provide useful information for adequately adopted equations which were derived from small scale laboratory experiments and applied to large bridge piers in field applications.
Identifier: FSU_migr_etd-1094 (IID)
Submitted Note: A Thesis Submitted to the Department of Civil and Environmental Engineering in Partial Fulfillment of the Requirements for the Degree of Master of Science.
Degree Awarded: Fall Semester, 2005.
Date of Defense: October 28, 2005.
Keywords: FLUENT, Numerical Simulation, Scale Effects, Hydraulic Similarity, Local Scour
Bibliography Note: Includes bibliographical references.
Advisory committee: Wenrui Huang, Professor Directing Thesis; Makola Abdullah, Committee Member; Nur Yazdani, Committee Member.
Subject(s): Civil engineering
Environmental engineering
Persistent Link to This Record:
Owner Institution: FSU

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Yang, Q. (2005). Numerical Investigations of Scale Effects on Local Scour Around a Bridge Pier. Retrieved from