Modeling of slightly-compressible isentropic flows and compressibility effects on fluid-structure interactions

• Published in: Computers & fluids Vol. 182; pp. 108 - 117
• Main Authors: Zhang, Lucy T., Krane, Michael H., Yu, Feimi
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Ltd 30.03.2019; Elsevier BV
• Subjects: Acoustic waves; Compressibility effects; Computational aeroacoustics; Computational fluid dynamics; Deformation; Finite element method; Fluid flow; Fluid-structure interaction; Formability; Incompressible flow; Incompressible fluids; Model accuracy; Pseudo compressible; Slightly-compressible; Sound sources; Sound waves; Variations; Viscosity; Pseudo compressible; Computational aeroacoustics; Slightly-compressible; Fluid-structure interaction
• ISSN: 0045-7930; 1879-0747
• DOI: 10.1016/j.compfluid.2019.02.013

•Developed a slightly-compressible fluid model that captures generations and propagations of acoustic waves without full compressible terms.•Derived compressible terms for isentropic flows (aeroacoustics) that can be directly added onto the incompressible form of Navier–Stoke equation.•Verified accuracy of acoustic behaviors in test cases.•Captured acoustic waves in fluid-structure interactions and found differences in acoustic behaviors comparing to incompressible form. In this study, an aeroacoustic fluid model for slightly-compressible isentropic flows is developed and evaluated for its compressibility effects in the context of fluid-structure interactions. This model considers computational feasibility and accuracy by adding compressibility terms directly on the incompressible form of Navier–Stokes equation. Rather than solving for the full compressible form, our slightly-compressible form significantly reduces the complications in establishing stabilization and implementation of its finite element procedure, and yet still captures the fluctuating acoustic waves expected in the compressible form. Using this approach, we demonstrate that generations and propagations of acoustic waves can be accurately captured, without the inclusion of a fully compressible representation of the fluid. Upon the successful verification of its accuracy against analytical and known solutions, we then evaluate the fluid compressibility effect on fluid-structure interactions. Our results show that comparing to an incompressible fluid, a deformable solid generates sound waves while it is driven by the flow and vibrates in the fluid. A periodic volume change in the fluid is also observed, which can be considered as a sound source.