Development of Fluid-Structure Acoustic Interaction (FSAI) Solver
Fluid-Structure Acoustic Interaction (FSAI) is a multi-physics phenomenon that involves the interplay between a deformable or moving structure and a surrounding or internal fluid flow generating acoustic signals. FSAI simulations are crucial in various fields, including aerospace, civil engineering, and biomedical engineering. For instance, they aid in designing aerodynamically efficient aircraft wings, analyzing the structural integrity of bridges under wind loads, and understanding blood flow-induced sound patterns in arteries interacting with arterial walls.
The development of an FSAI solver involves addressing several key challenges. These include accurately modeling the fluid flow and structural behavior, handling the dynamic interaction between the fluid and structure, allowing acoustic signals to smoothly pass out of domain, and efficiently solving the coupled equations governing the system.
Objectives
The primary objectives of this research work are:
To develop a unified computational framework for simulating fluid-structure interaction problems in both 2D planar and axisymmetric geometries.
To propose a novel hybrid method for dynamic mesh generation in the fluid domain, aiming to reduce computational cost while maintaining mesh quality.
To implement a fully implicit coupling between the fluid and structural solvers to enhance the stability and accuracy of the simulations.
To validate the developed FSI solver using benchmark problems and assess its order of accuracy.
To investigate the performance of the proposed hybrid mesh generation method compared to traditional methods.
To extend the FSI solver to include flow-induced acoustics, enabling the prediction of noise generated due to fluid-structure interactions.
Development Strategy
The FSI solver is developed using a partitioned approach, where the fluid and structural domains are solved separately with appropriate coupling at the interface. The fluid flow is modeled using the Arbitrary Lagrangian-Eulerian (ALE) formulation, which allows the fluid mesh to deform in response to the structural motion. The structural deformations are modeled using the Lagrangian formulation, where the mesh moves with the structure.
A finite volume method (FVM) is employed for discretizing both the fluid and structural equations on a curvilinear grid. This unified discretization approach simplifies the implementation and ensures accurate data transfer between the fluid and solid domains.
A hybrid mesh generation method is proposed, combining the strengths of the solid extension mesh motion (SEMM), mesh renode-reconnect (MRR), and automatic mesh motion (AMM) techniques. This hybrid approach aims to optimize the computational cost while maintaining mesh quality during dynamic simulations.
A fully implicit coupling scheme is implemented between the fluid and structural solvers. This implicit coupling enhances the stability of the simulations, especially for problems involving large structural deformations.
To extend the FSI solver to include flow-induced acoustics, the linearized perturbed Euler equations (LPEE) are employed. A low Mach number approximation is applied to the LPEE to simplify the equations and improve computational efficiency for low-speed flows.
Results
The developed FSI solver is validated using several benchmark problems, including lid-driven cavity flow with a flexible plate, pulsatile flow in a flexible artery, and flow-induced vibrations of a cylinder. The results demonstrate excellent agreement with published numerical data, validating the accuracy and reliability of the solver.
The order of accuracy study confirms that the solver is second-order accurate in both space and time. The performance study of the hybrid mesh generation method shows a significant reduction in computational time compared to the traditional AMM method, highlighting its efficiency.
The extended FSI solver with flow-induced acoustics capabilities is validated using test cases involving flow over a cylinder and a vibrating sphere. The results demonstrate the solver's ability to accurately predict acoustic perturbations generated due to fluid-structure interactions.
Major Accomplishments/Achievements
The major accomplishments of this research work include:
Development of a unified FSI solver for 2D planar and axisymmetric geometries, providing a versatile tool for simulating a wide range of FSI problems.
Proposition of a novel hybrid mesh generation method that significantly reduces computational cost while maintaining mesh quality.
Implementation of a fully implicit coupling scheme that enhances the stability and accuracy of FSI simulations.
Extension of the FSI solver to include flow-induced acoustics, enabling the prediction of noise generated due to fluid-structure interactions.
Validation of the FSAI solver using benchmark problems and demonstration of its second-order accuracy in space and time.
Successful application of the solver to various FSAI problems, including physiological flows and flow-induced vibrations.
Overall, this research work presents a significant advancement in the field of computational FSAI, providing a robust and efficient tool for simulating complex FSAI phenomena. The developed solver has the potential to impact various engineering and scientific applications, contributing to the design and analysis of advanced systems involving fluid-structure interactions.
Supervisor
Dr. Atul Sharma,
Professor, Department of Mechanical Engineering
Indian Institute of Technology, Bombay
Co-Supervisor
Dr. Janani Srree Murallidharan,
Assistant Professor, Department of Mechanical Engineering
Indian Institute of Technology, Bombay