Predictive Simulations of Turbulent Flows Over Compliant Surfaces
Abstract
SOW Much of our fluid dynamical intuition and understanding of wall turbulence are based on studiesof flows over rigid walls. However, when the surface is compliant, new phenomena arise and theresulting modifications to the flow defy intuition across Reynolds numbers. The most interestingregime is one where two-way coupling between the compliant material and fluids stresses is established.Specifically, when the Young modulus of elasticity of the material are commensuratewith the fluid shear stress near the wall, both longitudinal and transverse waves can be sustainedin the compliant material. Depending on the flow regime, these waves may be very apparent orobfuscated by the mutli-scale nature of the material deformation as it is buffeted by turbulent eddies.No matter their prominence, these waves are two-way coupled with the hydrodynamic fieldbecause they are caused by the turbulence and also modify the flow. The resulting turbulent drag isincreased, and above the surface the mean-flow and Reynolds-shear-stress profiles are qualitativelydifferent from what would be expected for flow over a rigid rough surface. The connection, or coupling,between the turbulent structures within the flow and the surface deformation, and how theseinteractions lead to the above flow modifications remain open questions. These complex interactionswill be studied in detail by performing high-fidelity modeling of the compliant material, andfully coupling its deformation with the turbulence which will be resolved using direct numericalsimulations. The computations will also provide new insight regarding the hydro-acoustic fieldsgenerated by these interactions. By matching the parameters of our simulations to an existingexperimental effort at Johns Hopkins University, we will be able to perform direct comparisons.We will also use variational techniques to infuse experimental measurements directly into the simulations.Our simulated flow fields are therefore guaranteed to be physically relevant, and wecan make predictions at higher spatio-temporal resolution than the experiments. Using the samevariational techniques, we will solve two inverse problems of interest: Firstly, we will identifythe sources of important events (shear waves, velocity profile, radiated noise,...etc) by computingtheir sensitivity to the system state. Secondly, we will explore optimal material properties that canachieve an objective of interest, e.g. minimize radiated sound or minimize diffraction of incidentacoustic waves.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Aug 31, 2020
- Source ID
- N000142012778
Entities
People
- Tamer A. Zaki
Organizations
- Johns Hopkins University
- Office of Naval Research
- United States Navy