Two-dimensional numerical simulations are used to study the coupled fluid–structure–electric interaction of a simple model an inverted piezoelectric flag, and investigate dynamics flow–structure this configuration as well its energy harvesting performance. In particular, dynamic response flag associated flow patterns examined for range inertia, bending stiffness Reynolds numbers, categorized into distinct vibrational states based on symmetry motion amplitude. Simulations indicate that...

The flow-induced fluttering motion of a flexible reed inside heated channel is modeled numerically and used to investigate the relationship between aeroelastic vibration heat-transfer enhancement. An immersed boundary method developed solve coupled flow-structure-thermal problem, simulations show that vibrating significantly increases mean heat flux through channel, as well thermal performance, quantified in terms enhancement factor. effect material properties on vibratory dynamics transfer...

We examine numerically the performance of a thin foil reinforced by embedded rays resembling caudal fins many fishes. In our study, supporting are depicted as nonlinear Euler-Bernoulli beams with three-dimensional deformability. This structural model is then incorporated into boundary-element hydrodynamic to achieve coupled fluid-structure interaction simulation. Kinematically, we incorporate both homocercal mode dorso-ventral symmetry and heterocercal asymmetry. Using mode, results...

The deformability of insect wings is associated with the embedded skeleton (venation). In this paper, aerodynamic performance nonuniform flexibility computationally investigated. By using a two-dimensional rendition, underlying veins are modeled as springs, and membrane flexible plate. focus on effects detailed distribution vein upon such wing in generation lift force. Specifically, we interested finding importance leading edge strengthening. Towards end, performances three wings, rigid...

The stability of a thin flexible plate confined inside an inviscid two-dimensional channel is examined using nonlinear eigenvalue analysis method. A new Green’s function for the vortex wake channel, as well its rapidly convergent series approximation, proposed. Comparison with fully coupled Navier–Stokes fluid–structure interaction model indicates that current successfully predicts flutter boundary plate. also shows confinement has destabilizing effect on heavy plates. Furthermore,...

Abstract A numerical model of a ray-reinforced fin is developed to investigate the relation between its structural characteristics and force generation capacity during flapping motion. In this two-dimensional rendition, underlying rays are modelled as springs, membrane flexible but inextensible plate. The kinematics characterized by oscillation frequency phase difference different (which generates pitching motion). An immersed boundary method (IBM) applied solve fluid–structure interaction...

Recent studies have shown that the effectiveness of face masks depends not only on mask material but also their fit faces. The porosity and dictate amount filtered flow perimeter leakage. Lower is usually associated with better filtration; however, lower results in higher resulting leakage jets generated from different types faces porosities are particular interest. Direct numerical simulations dynamics respiratory events while wearing a can be used to quantify distribution leaks. Here, we...

We numerically examine the fluid-structure interaction and force generation of a skeleton-reinforced fin that geometrically, structurally kinematically resembles pectoral fish during labriform swimming. This contains soft membrane with negligible bending stiffness 12 embedded rays (modeled as beams). A potential flow-based boundary element model is applied to solve fluid flow around fin, in which vorticity field modeled thin sheets shed from prescribed locations (the sharp trailing edge)....

Abstract The wake dynamics behind a compliant floating offshore wind turbine (FOWT) with two alternative supporting platforms of spar buoy and barge platform are studied numerically. computational model is based on the large eddy simulation use actuator disk FOWT rotor in which circular discretized an unstructured two‐dimensional triangular mesh structured three‐dimensional Cartesian grid fluid domain. motions calculated for laminar turbulent inflow conditions. flow solver verified through...

The use of face masks by the general population during viral outbreaks such as COVID-19 pandemic, although at times controversial, has been effective in slowing down spread virus. extent to which mitigate transmission is highly dependent on how well mask fits each individual. fit simple cloth face, resulting perimeter leakage and efficacy, are expected be type facial topology. However, this effect has, date, not adequately examined quantified. Here, we propose a framework study efficacy...

The phenomenon of electroconvection has attracted attention because it the potential to improve ion transport on polarized surfaces, reducing plateau region limiting current. Previous observations for DC voltages indicate that patterned surfaces or unipolar charge injection significantly enhance through electroconvection. However, creating and maintaining convection cells crucial is challenging under AC due alternating direction electric field, which can cause instabilities. In this article,...

Heat transfer enhancement due to flapping flags in a heated duct flow is studied using three-dimensional (3D) fully coupled fluid–structure–thermal simulations. Following prior work, which was limited two-dimensional models, we examine the mechanisms and heat performance for more realistic, 3D model of flag rectangular exchanger. We then role aspect-ratio spanwise confinement, are key design parameters this device. find that narrow do not exhibit sufficiently energetic generate any...

The ciliary locomotion and feeding of an axisymmetric micro-swimmer in a complex fluid whose viscosity depends on nutrient concentration are investigated numerically. is modeled as having spheroidal geometry, beating by slip velocity; i.e. squirmer adapted. Looking at the coupling between swimming squirmers, it found that speed most affected non-uniform environment when ratio advection-forces to diffusion-transport, characterized nondimensional Pecl\'et number, moderate ($\text{Pe}\approx...

We investigate the thrust generation capacity of a thin foil consisting membrane strengthened by embedded rays that is geometrically, structurally and kinematically similar to pectoral fins bony fishes during lift-based labriform locomotion. Our numerical model includes fully nonlinear Euler-Bernoulli beam skeleton boundary-element surrounding flow field. The fin undergoes dorso-ventral flapping activated rotations rays. Both trailing edge vortices (TEV) leading (LEV) are accounted for...

By using a two-dimensional model of ray fins, we numerically investigate the thrust generation by closely-coupled fins with an immersed boundary approach. The concentration is on performance enhancement through fin–fin interactions and underlying vortex control mechanisms in three representative systems, two-fin tandem configuration, parallel three-fin triangular configuration. In all these systems can be significantly increased comparison single fins. Unlike previous studies which gap phase...

We report three stages for locomotion of a helical swimmer in yield stress fluids. In the first stage, must overcome material's strain to generate rotational motion. However, exceeding threshold is not sufficient locomotion. Only when viscous forces are sufficiently strong plastically deform material finite distance away from will net occur. Once underway third retards swimming at small pitch angles. Conversely, large angles, dominates flow by enhancing speed. Flow visualizations reveal...

To understand flow-induced vibrations of deformable objects, we numerically investigate dynamics a pressurized elastic ring pinned at one point within uniform flow by using an immersed-boundary algorithm. The boundary the consists fibre with no bending stiffness, which can be modelled as linear spring constant k and zero unstretched length. vibration is decomposed into two parts: pitching motion that includes rigid-body rotation flexible in transverse direction, tapping longitudinal...

View Video Presentation: https://doi.org/10.2514/6.2021-0489.vid An experimental investigation has been carried out to understand the effects of coupling between an unsteady impinging oblique shock and a compliant panel at Mach 2 across two impingement locations three cavity pressures. High-speed shadowgraph surface oil flow visualization techniques were used visualize interaction region, measure separation length on rigid plate, compare it with respective panel. Single point capacitive...