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    <title>Transport Research International Documentation (TRID)</title>
    <link>https://trid.trb.org/</link>
    <atom:link href="https://trid.trb.org/Record/RSS?s=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" rel="self" type="application/rss+xml" />
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    <language>en-us</language>
    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
    <docs>http://blogs.law.harvard.edu/tech/rss</docs>
    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
    <image>
      <title>Transport Research International Documentation (TRID)</title>
      <url>https://trid.trb.org/Images/PageHeader-wTitle.jpg</url>
      <link>https://trid.trb.org/</link>
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    <item>
      <title>Numerical simulation of vortex-induced vibration of tandem circular cylinders near a plane boundary</title>
      <link>https://trid.trb.org/View/2638135</link>
      <description><![CDATA[This paper numerically investigated vortex-induced vibration (VIV) of two tandem circular cylinders near a stationary plane boundary across a range of reduced velocities from 1 to 16, gap ratios (G/D = 2, 3, 4), wall proximity (E/D = 1) and the Reynolds number ranging from 4500 to 36000. Results indicate that the downstream cylinder (C2) exhibits significantly higher transverse, and in-line vibration amplitudes compared to the upstream cylinder (C1), particularly when near a stationary wall. The downstream cylinder also displays complex vibration behaviours, including multi-peak frequency responses, which are influenced by the wake interaction from the upstream cylinder. Furthermore, desynchronization is observed, with the two cylinders oscillating at frequencies that are slightly different from each other, as a result, the phase between the vibrations of the two cylinders varies with time periodically between −180° and 180°. These findings provide useful insight into the dynamic behaviour of multi-cylinder systems near boundaries and have practical implications for the design of offshore structures.]]></description>
      <pubDate>Mon, 27 Apr 2026 15:01:20 GMT</pubDate>
      <guid>https://trid.trb.org/View/2638135</guid>
    </item>
    <item>
      <title>Modifications in the wake of a transversely oscillating circular cylinder by additional rotational motions</title>
      <link>https://trid.trb.org/View/2653086</link>
      <description><![CDATA[Modifications in the wake of a transversely oscillating circular cylinder by additional oscillatory or uniform rotational motions are presented. Wake of a purely translating (Ty) cylinder is characterized by: Lock-in region (matching of vortex shedding and excitation frequencies), symmetric vortex shedding, high drag, low fluctuations in the moment with zero average and dependence of energy transfer on excitation amplitude & frequency. Additional oscillatory rotation (Rₒ) causes: early (at lower excitation frequency) entry and exit of Lock-in, increment in drag, amplified fluctuations in the moment with zero average, dependence of energy transfer on a competition between viscous damping & flow inertia and quasi-periodic flow. Additional uniform rotation (Rᵤ) causes: early exit of Lock-in, loss of symmetric vortex shedding with negative average lift, decrement in drag, low fluctuations in the moment with negative average and energy transfer dictated by flow inertia. It may be proposed that Ty+Rₒ has higher potential to modify the wake than Ty+Rᵤ. This study predicts the wake characteristics of the corresponding Vortex-Induced Vibration (VIV).]]></description>
      <pubDate>Wed, 08 Apr 2026 13:57:22 GMT</pubDate>
      <guid>https://trid.trb.org/View/2653086</guid>
    </item>
    <item>
      <title>Wake-vortex transitions of a submerged horizontal cylinder under combined wave–current action</title>
      <link>https://trid.trb.org/View/2649726</link>
      <description><![CDATA[The nonlinear interaction between ocean waves and currents significantly modifies wake dynamics around submerged horizontal cylinders, with important consequences for hydrodynamic loading on offshore structures. This study combines laboratory experiments, synchronized three-component load measurements, and flow visualization to investigate wake-vortex transitions and vertical force frequency characteristics for a fully submerged horizontal cylinder in the ranges Re = 1.2 × 10⁴–4.8 × 10⁴ and Kc = 0.09–2.19. The vertical force spectra are classified into three distinct modes: wave-dominated (mode I), subharmonic (mode II), and vortex-dominated (mode III), according to the position of the low-frequency component fl in the spectra. The non-dimensional low frequency fₗT is primarily governed by Re, the velocity ratio λ = U/Uw, and the period ratio τ = TU/D, and captures the mechanism of spectral mode transitions. Vortex identification reveals that wake-vortex patterns evolve from nearly symmetric, wave-locked structures in mode I to alternating and asymmetric shedding in modes II and III. The broadband low frequency vertical force results from transitions between different shedding modes, with mode III being more unstable and sensitive to such transitions. The results provide a quantitative basis for evaluating mode transition mechanisms for the horizontal cylinder under combined wave–current action.]]></description>
      <pubDate>Fri, 03 Apr 2026 12:12:45 GMT</pubDate>
      <guid>https://trid.trb.org/View/2649726</guid>
    </item>
    <item>
      <title>Numerical study on the suppression of vortex-induced vibration with active controlled fin stabilizers</title>
      <link>https://trid.trb.org/View/2644034</link>
      <description><![CDATA[Inspired by the ship roll stabilization fin stabilizers, this paper innovatively proposes an active vibration suppression method by arranging rotating hydrofoil system controlled by Proportional-Integral-Derivative (PID) strategy. Using the computational fluid dynamics (CFD) method, a two-degree-of-freedom (2-DOF) system is established to model the main cylinder-hydrofoil system, aiming to investigate the influence of hydrofoils on the vortex-induced vibration (VIV) response. The effects of hydrofoil quantity, size, and spacing from the cylinder on suppression efficiency were studied to determine an appropriate hydrofoils arrangement strategy. The hydrofoil system achieves vibration suppression by generating counter forces and controlling the wake structure. Theoretical analysis shows that the transverse vibration velocity is more suitable as the feedback signal for the PID controller. Since integral control introduces a phase lag that degrades suppression performance, PD control demonstrates superior temporal efficacy and dynamic stability. Furthermore, phase-averaged pressure fields and spectral proper orthogonal decomposition (SPOD) were employed to extract the dominant flow dynamics. The results conclusively demonstrate that the PID-controlled hydrofoil system significantly reduces the low-pressure region around the main cylinder and primarily attenuates energy transfer to the external flow field, thereby achieving vibration suppression efficiencies of 94–98 % across different reduced velocities. Findings provide valuable insights for the optimal design of this innovative active vibration suppression device.]]></description>
      <pubDate>Fri, 20 Mar 2026 14:47:18 GMT</pubDate>
      <guid>https://trid.trb.org/View/2644034</guid>
    </item>
    <item>
      <title>Influence of high-frequency micro-vibrations on hydrofoil vortex shedding</title>
      <link>https://trid.trb.org/View/2634023</link>
      <description><![CDATA[Hydrofoils are widely used in marine applications, and significant progress has also been made in the study of their fluid-structure interaction. However, in practical applications, high-frequency micro-vibrations (above tens of Hz, with micrometer-scale vibrations) induced by ship propulsion systems can still alter the vortex shedding behavior and wake dynamics of hydrofoils. This study systematically analyzes the lock-in mechanism between structural vibrations and vortex shedding by combining smart actuators (MFC) with a hydrofoil and observing changes in the flow field. Through a combination of simulations and experiments, we investigate key physical mechanisms such as the amplitude and phase variations of pressure and velocity during the lock-in process, as well as the energy transfer process. Additionally, the phenomenological model provides a theoretical explanation for the lock-in mechanism. These findings provide important insights into the development of fluid-structure interaction analysis for underwater structures such as hydrofoils, propeller blades, and rudders, and offer potential solutions for flow control applications in marine engineering.]]></description>
      <pubDate>Tue, 10 Mar 2026 09:55:43 GMT</pubDate>
      <guid>https://trid.trb.org/View/2634023</guid>
    </item>
    <item>
      <title>Noise reduction of high-speed train pantograph cavity based on the combination of active jet and vortex generator</title>
      <link>https://trid.trb.org/View/2598439</link>
      <description><![CDATA[With the continuous increase in operating speeds of high-speed trains, aerodynamic noise generation in the pantograph cavity region has emerged as a critical challenge in railway engineering. To address this issue, this study proposes an innovative hybrid flow control strategy combining an active leading-edge jet with vortex generators at the cavity base. Through synchronized implementation of large eddy simulation (LES) for turbulent flow resolution and the Ffowcs-Williams-Hawkings (FW-H) acoustic analogy for noise propagation modeling, this paper systematically investigated the noise suppression mechanisms induced by jet parameter optimization. Numerical results demonstrate that this synergistic control approach achieves broadband noise reduction across monitoring positions. At 400 km/h operation speed, the proposed configuration yields average sound pressure level (SPL) reductions of 2.96 dB, 3.05 dB, and 3.00 dB at 7.5 m, 12.5 m, and 25 m observation points, respectively. Furthermore, parametric studies reveal that jet orifice contraction angle optimization plays a important role, with the 15° configuration exhibiting maximum noise reduction through enhanced flow attachment and vortex shedding frequency modulation. This research provides theoretical foundations and technical references for pantograph aerodynamic noise control systems of high-speed trains.]]></description>
      <pubDate>Mon, 24 Nov 2025 15:30:52 GMT</pubDate>
      <guid>https://trid.trb.org/View/2598439</guid>
    </item>
    <item>
      <title>Role of the vortex shedding force played in the added damping of a NACA 0009 hydrofoil in the lock-in region</title>
      <link>https://trid.trb.org/View/2573946</link>
      <description><![CDATA[Some researchers have shown that when blade-like hydrofoils vibrate with a small amplitude in the lock-in region, negative added damping can occur, which can reversely increase the hydrofoils’ vibration amplitude. The negative added damping in the lock-in region may have a relationship with the vortex shedding behind the trailing edge of the hydrofoil, and the role the vortex shedding played in the added damping in the lock-in region has still not been clear. In this paper, the role of the vortex shedding force played in the added damping of a NACA 0009 hydrofoil in the lock-in region has been studied through theoretical and numerical methods. Results show that the negative added damping in the lock-in region is mainly caused by the positive phase difference between the vortex-shedding-induced modal force component with the same frequency as the vibration and the vibration displacement. The occurrence mechanism of the positive phase difference and the influence of the vibration amplitude in the lock-in region are also talked about. The conclusions in this paper can help the authors understand how to increase the added damping in the lock-in region to reduce the vibration amplitude of submerged structures.]]></description>
      <pubDate>Fri, 25 Jul 2025 11:35:06 GMT</pubDate>
      <guid>https://trid.trb.org/View/2573946</guid>
    </item>
    <item>
      <title>Horseshoe vortex formation around a rotationally oscillating cylinder: Experimental investigation with PIV</title>
      <link>https://trid.trb.org/View/2564564</link>
      <description><![CDATA[This study aimed to experimentally investigate the horseshoe vortex region of a round cylinder positioned on a flat surface in a water channel at different rotational speeds and different frequencies. Experiments were carried out at three distinct oscillation amplitudes (θA = 60°, 120°, and 180°) and four different forcing frequencies (FR = 0.1, 0.3, 0.6, and 1.2) under a Reynolds number of 5000. Compared to the state of a stationary cylinder, applying a rotational oscillation to the cylinder changed the flow structure mostly in the wake region of the horseshoe vortex structure. Furthermore, as the rotation angle increased (θ = 120° at FR = 0.1 and θ = 180° at FR = 0.6), the vortex core progressively moved closer to the cylinder surface, leading to a reduction in the dead flow zone. Among the investigated cases, the condition of θ = 180° with FR = 0.3 was particularly notable, as it eliminated the dead flow zone in the cylinder wake and demonstrated a clearer effect of the flow control method within the horseshoe vortex region. These findings suggest that rotational oscillation can effectively modify the flow structure and mitigate flow separation in the horseshoe vortex region.]]></description>
      <pubDate>Tue, 24 Jun 2025 15:24:48 GMT</pubDate>
      <guid>https://trid.trb.org/View/2564564</guid>
    </item>
    <item>
      <title>Research on the Noise Reduction Mechanisms of Bionic Airfoils with Different Serrated Trailing-Edge Structures</title>
      <link>https://trid.trb.org/View/2522050</link>
      <description><![CDATA[Inspired by the silent flight capability of owls, the serrated trailing-edge design is recognized as an effective method to control trailing-edge interference noise arising from turbulent boundary layers. Based on the NACA0018 airfoil and the serrated structures found in owl wings, this paper designs five different bionic airfoils featuring varying serration heights and spacings. By utilizing large eddy simulation and the Ffowcs Williams-Hawkings acoustic analogy model, we explore the noise reduction mechanism of the serrated trailing edge and validate the accuracy of the numerical methods employed. At an angle of attack of 6°, the study investigates the effects of serration spacing and height on the flow structure near the trailing edge, far-field noise, and noise reduction capabilities of the airfoils. It is found that the serrated trailing edge mitigates the separation of the turbulent boundary layer near the trailing edge, causing separation vortices to shift toward the trailing edge and enabling fluids to adhere more readily to the airfoil surface. This, in turn, reduces noise generated by vortex shedding. As the serration height 𝐻 increases, the noise reduction effect becomes more pronounced, whereas the effect of serration width 𝐿 on noise reduction is less distinct. Among the designs, the H2.5L10 and H5L5 airfoils exhibit the best noise reduction performance. Furthermore, acoustic field analysis reveals that the bionic serrations are beneficial in reducing mid-to-low-frequency noise. Through a comprehensive analysis of both flow and acoustic fields, this paper sheds light on the influence of serration parameters on airfoil noise reduction, providing crucial theoretical foundations for noise reduction in large-scale equipment such as axial flow fans and wind turbines.]]></description>
      <pubDate>Thu, 17 Apr 2025 16:55:17 GMT</pubDate>
      <guid>https://trid.trb.org/View/2522050</guid>
    </item>
    <item>
      <title>Tracking of forward keel vortex of a ship at drift angle in shallow water</title>
      <link>https://trid.trb.org/View/2510563</link>
      <description><![CDATA[The objective of this study is to identify the trajectory of the vortex shed from the forward body of a vessel sailing at high drift angle in shallow water by analysing pre-existing video recordings of scaled model tests. The focus is on the trajectory of the vortex and the angle at which it detaches from the hull and is shed into the wake. To monitor these flow details, the Particle Tracking Velocimetry (PTV) technique is applied to analyse the model test video recordings, tracking suspended particles in the water-column in the gap between the model bottom and the tank floor. Detailed information of the flow mean velocity and flow angle on the vessel's leeward side are presented. It is documented that for a water-depth to draught ratio of H/T = 1.5 the forward keel shed vortex detaches from the hull and is advected in the ship's wake at a variable angle, depending on the steady drift angle at which the vessel is advancing. The experimental observations show a behaviour for limited water depth that contrasts with the deep water case, where the vortices trail in the wake at an angle of half the drift angle.]]></description>
      <pubDate>Wed, 19 Feb 2025 17:11:57 GMT</pubDate>
      <guid>https://trid.trb.org/View/2510563</guid>
    </item>
    <item>
      <title>Experimental Study of the Vibration of Blades Induced by Flow and Sound in a Plane Cascade under Low Wind Speed</title>
      <link>https://trid.trb.org/View/2360862</link>
      <description><![CDATA[Vibration causes compressor rotor blade failure that affects aeroengine safety. Therefore, a plane cascade model of rotor blades was developed to capture the vibration phenomenon. The blade vibration, vortex shedding, and aerodynamic noise were measured. The results indicate that flow and noise induce a natural vibration mode, resulting in torsional vibration fatigue damage. The frequency of trailing edge vortex shedding is consistent with the frequency of tip clearance leakage vortex pulsation and is close to the second-order modal frequency of the blade, which induces torsional vibrations. The triple frequency of the background noise peak frequency in the wind tunnel is consistent with the first standing wave acoustic resonance modal frequency of the cascade experimental section duct and is close to the third-order natural modal frequency of the blade, which induces bending and torsional vibrations. This research provides guidance for the study of rotor blade multifield coupling-induced vibration.]]></description>
      <pubDate>Mon, 20 May 2024 14:02:20 GMT</pubDate>
      <guid>https://trid.trb.org/View/2360862</guid>
    </item>
    <item>
      <title>Non-linear vibration of free spanning subsea pipelines with multi-dimensional mid-plane stretching</title>
      <link>https://trid.trb.org/View/2310967</link>
      <description><![CDATA[In the absence of full-length support, subsea pipelines can experience significant oscillations due to flow induced vortex shedding that may result in the accumulation of fatigue damage over time. Such oscillations reflect the intricate interplay between the structural characteristics of the pipeline and the unsteady flow field, which can generate periodic shedding of vortices and pulsating forces. Conventional finite element models and/or empirical relations (e.g. codes of practice) are usually sufficient to predict the frequencies and mode shapes of vibrating free-spanning pipelines, which facilitates the assessment of their fatigue damage. However, the effects of multi-dimensional mid-plane stretching (i.e. coupled non-linear deformations) on the stability and performance of pipelines are still unknown. Here, the authors formulate the governing equations of free spanning pipelines experiencing lateral and transversal non-linear deformation that apply to in-line and cross-flow vortex induced vibration (VIV), investigate the effect of lateral mid-plane stretching on the response of the structure when it is partially supported by seabed shoulders and constrained by uneven natural supports or buckle initiators, and demonstrate that transversal mid-plane stretching transforms the pipeline into a non-linear oscillator with hardening stiffness and single well potential energy (i.e. energy potential resembling a well-shaped curve). The authors found that lateral mid-plane stretching reduces the overall deflection of a free spanning pipeline, increases the frequency of vibration for various axial forces and seabed/support stiffnesses, and reduces the effective length at various seabed stiffnesses and axial forces. In addition, considering the transversal mid-plane stretching and solving the problem using Galerkin’s method showed that the frequency of resonance increases with the amplitude of vibration and the increase is a function of damping and non-linear stiffness. The authors’ results prove that beyond a critical level of forced oscillation, the pipeline experiences a period doubling bifurcation, which has been overlooked in existing predictive tools and codes of practice.]]></description>
      <pubDate>Tue, 26 Mar 2024 17:11:41 GMT</pubDate>
      <guid>https://trid.trb.org/View/2310967</guid>
    </item>
    <item>
      <title>Unsteady RANS and IDDES studies on a telescopic crescent-shaped wingsail</title>
      <link>https://trid.trb.org/View/2320645</link>
      <description><![CDATA[Over the years, several research projects have evaluated different concepts for wind-assisted propulsion, generally concluding that it can lead to significant fuel savings. The time-averaged propulsive performance of a single rigid wingsail has been analysed in previous studies. However, the unsteady characteristics of the external loads which may induce structural vibration are also important to be considered. In this study, full-scale simulations, with both unsteady RANS and IDDES methods, are performed to analyze the flow field. The paper's analysis includes flow separation and vortex shedding, the development and dissipation of wake vortices, and the lift reduction due to tip vortices. It also studies the telescopic function of the wingsail by analyzing sails with different heights and wind conditions. The paper concludes that the unsteady RANS and IDDES simulations make similar predictions for time-averaged loads but disagree on the unsteady characteristics. The IDDES simulations indicate more complex vortex-shedding phenomena.]]></description>
      <pubDate>Wed, 24 Jan 2024 16:54:15 GMT</pubDate>
      <guid>https://trid.trb.org/View/2320645</guid>
    </item>
    <item>
      <title>Mechanism and Aerodynamic Countermeasures of Vortex-Induced Vibration of a Cable-Stayed Bridge with Narrow ?-Shaped Girder Sections</title>
      <link>https://trid.trb.org/View/2254903</link>
      <description><![CDATA[In this study, the investigations on the mechanism and aerodynamic countermeasures (ACs) of vortex-induced vibration (VIV) for a narrow ?-shaped girder (NG) section with the aspect ratio of B/D = 5 (B is the width and D is the height of the main deck) are conducted. First, the wind tunnel tests on VIV of the NG section with/without ACs are carried out. Furthermore, numerical simulations of VIV of the NG section with/without AC-VII, namely combined AC of modified fairings and inclined deflectors, for wind attack angle of +3° are conducted via fluid–structure interaction, respectively. Moreover, the mechanism of VIV of the NG section is analyzed from the characteristics of vorticity, pressure, and vortex-induced force (VIF) distributions, respectively. The research results show that the original NG section exhibits obvious vertical and torsional VIV for wind attack angles of +3° and +5°, respectively. Moreover, the ACs of low vertical stabilizers and horizontal separators, which are commonly applied to suppress the VIV responses of the wide ?-shaped girder section with aspect ratio B/D = 10–14, cannot effectively suppress the VIV responses of the NG section with B/D = 5. However, the AC-VII can effectively suppress the VIV responses. For the original NG section, the shear layer separation vortices that are generated on the windward side will extend to the leeward of the section and form the periodic shedding vortex, which is the mechanism of the VIV of the NG section. However, the AC-VII effectively suppresses the scale and vorticity intensity of the upper dominant vortex, avoiding the appearance of the vortex acceleration region at the leeward of the NG section. Therefore, the vorticity intensity of the upper and lower dominant vortexes is reduced during the shedding process, and the peak value of the fluctuating pressure in the VIV’s driving region is reduced by 86%.]]></description>
      <pubDate>Mon, 16 Oct 2023 09:33:17 GMT</pubDate>
      <guid>https://trid.trb.org/View/2254903</guid>
    </item>
    <item>
      <title>Prediction of the Hydrodynamic Loads on a Full-Scale Caisson at High Reynolds Number</title>
      <link>https://trid.trb.org/View/2151369</link>
      <description><![CDATA[The paper reports on the computation of the hydrodynamic loads on a full-scale caisson at high Reynolds number in the presence of vortex shedding. The objective was to obtain reliable predictions of the resulting mean and fluctuating forces to guide the design of an actual caisson in the absence of relevant experimental data. A further objective was to investigate the effectiveness of alternative methods for the control of vortex shedding that can be implemented in practice. Two such methods were evaluated: (1) by rounding the corners of the rectangular-sectioned caisson, and (2) by the placement of a splitter plate in the separated wake region. The computations, which were performed using the OpenFOAM open-source software, were for a fixed caisson and hence did not account for motions due to vortex-induced vibrations. The effects of turbulence were accounted for by performing large-eddy simulations, and by using two-equation eddy-viscosity closures, one of which was specifically adapted to account for the interactions between the periodic vortex shedding and the random turbulence. The numerical accuracy was checked using the grid convergence index method, and the computations were extensively validated against data from relevant benchmark flows. The recommendations of this research were implemented in the design of a full-scale caisson that has since been deployed in a bridge construction project.]]></description>
      <pubDate>Wed, 28 Jun 2023 16:57:55 GMT</pubDate>
      <guid>https://trid.trb.org/View/2151369</guid>
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