December 4, 2024
Ehsan Izadpanah

Ehsan Izadpanah

Academic Rank: Associate professor
Address:
Degree: Ph.D in Mechanical Engineering
Phone: 09133570349
Faculty: Faculty of Engineering

Research

Title
Numerical investigations of vortex-induced vibration of two cylinders in tandem arrangement close to free surface
Type Thesis
Keywords
ارتعاش القايي گردابه، سطح آزاد، دو استوانه، عدد فرود، سرعت كاهيده
Researchers pedram latif (Student) , Seyed Hamed Meraji (Primary advisor) , Ehsan Izadpanah (Primary advisor) , Mohammad Vaghefi (Advisor)

Abstract

Structures and marine facilities play a crucial role in economic development and international communications. These installations include ports, bridges, tunnels, pipelines, and offshore oil and gas platforms, contributing significantly to maritime transportation and energy resource extraction. Many of these structures are submerged in water, subject to hydrodynamic forces due to marine currents. Therefore, investigating fluid-structure interaction is crucial in designing these structures. Additionally, when multiple structures are positioned together in the sea, it can impact the flow patterns and forces acting on the structures. This study focuses on the effect of an important phenomenon in fluid-structure interaction called vortex-induced vibration, examining its impact on two cylinders near the free surface. The simulation utilizes ANSYS Fluent software, employing the Eulerian-Eulerian approach and fluid volume method to track the free surface. The study is conducted in two dimensions, considering irregularities and for a laminar flow regime. To validate the study, four different scenarios are examined for stationary and vibrating cylinders in single-phase and two-phase flows, yielding good agreement with existing literature. The effects of reduced velocity, Froude number, and cylinder spacing on hydrodynamic characteristics and vibration response are investigated. Results indicate that with increasing reduced velocity, the average in-line and transverse displacement of the front and rear cylinders increases. The displacement range of the rear cylinder, along with its hydrodynamic coefficients, are higher that of the front cylinder. Increasing the Froude number leads to the instability of the free surface, the formation of vortices, and even the suppression of vortex shedding from the cylinder. At Froude number 0.3, as the cylinder spacing increases, instability in the free surface and the vortices formed behind the second cylinder become more pronounced. Furth