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    <title>Transport Research International Documentation (TRID)</title>
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    <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>
    </image>
    <item>
      <title>Multi-objective optimization of the Myring-style shape considering direct sailing resistance and flow-induced noise</title>
      <link>https://trid.trb.org/View/2604742</link>
      <description><![CDATA[This study addresses the shape optimization of underwater vehicles and proposes a design optimization scheme for the Myring-style shape by incorporating direct sailing resistance and flow-induced noise. Numerical simulation methods for the resistance and flow-induced noise are established, and their effectiveness is validated. Integrating CATIA and STAR-CCM+ within the modeFRONTIER platform enables the parametric design of the Myring-style shape,and the calculation of flow-induced noise was accomplished through the automated analysis based on resistance. Representative surrogate models are tested and compared; high-accuracy models for resistance and flow-induced noise are consequently identified. A multi-objective optimization model based on the Kriging framework is then constructed for the Myring-style shape. Using the nondominated sorting genetic algorithm II, multi-objective optimization is performed. Comparative results indicate that relative to the initial design, the Pareto front solutions are improved for some objectives, with certain solutions achieving enhancements across all objectives, thereby validating the effectiveness of the proposed optimization process.]]></description>
      <pubDate>Mon, 02 Mar 2026 08:55:13 GMT</pubDate>
      <guid>https://trid.trb.org/View/2604742</guid>
    </item>
    <item>
      <title>Hydrodynamic performance and wave dynamics in the moonpool of a ship. Part I: Froude number effects on resistance and flow regime</title>
      <link>https://trid.trb.org/View/2604982</link>
      <description><![CDATA[This study investigates the hydrodynamic performance and wave dynamics of a slender moonpool during navigation, using computational fluid dynamics (CFD). The KCS model modified by adding a slender moonpool in the middle of the hull was employed as the subject of this research. The simulations were performed using interFoam solver in the OpenFOAM, employing the PIMPLE algorithm and the SST k-ω turbulence model to analyze resistance and flow patterns under different Froude numbers. The results indicate that, owing to the high length-to-draft and length-to-breadth ratios, the internal vortex structures of the slender moonpool differ substantially from those of conventional well-type moonpools. The flow field in the forepart resembles a hydraulic jump, and undergoes significant transitions around Froude number Fₙ = 0.18. In contrast, the aft region exhibits a relatively independent flow pattern, with weakened wave reflection and elongated oscillation periods. Regarding resistance and internal wave behavior, the oscillation periods deviate considerably from conventional empirical formulas: the sloshing period is found to be 2.500 s, while the piston period ranges from 0.417 to 0.500 s and is influenced by the Froude number. At Fₙ = 0.22, the amplitude of resistance oscillations reaches up to 14 % of the mean resistance, and the maximum wave height inside the moonpool corresponds to 28.7 % of the ship's draft. Furthermore, the effects of viscous forces on the sidewalls, as well as lateral inflow, are pronounced and cannot be neglected.]]></description>
      <pubDate>Mon, 13 Oct 2025 13:53:24 GMT</pubDate>
      <guid>https://trid.trb.org/View/2604982</guid>
    </item>
    <item>
      <title>Modeling and Evaluation of Fluid Flow Resistance Characteristics of the Cooling Channel in the Aircraft Oil-Cooled Electric Machine</title>
      <link>https://trid.trb.org/View/2511799</link>
      <description><![CDATA[Oil cooling technique is one of the important ways to reduce the temperature rise and enhance the power density of aircraft electric machines (EMs). However, the high viscosity of the oil leads to high flow resistance, which may reduce the efficiency of the hydraulic system and damage the components. This article conducts research on the flow resistance characteristics of cooling channels. First, considering computational efficiency and accuracy, the influence of mesh type, size, and boundary layers on the cell count and calculation results is compared and summarized. Then, computational fluid dynamics (CFD) models for the series cooling channel and split-flow cooling channel are established. Another split-flow method is explored to optimize the cooling channel. Based on CFD and theoretical formulas, the influence mechanism of channel type and flow rate on flow resistance is revealed. Further, the heat-pressure ratio (HPr) is defined as an indicator to evaluate the heat dissipation capability of cooling structures. Finally, the pressure test models are constructed by 3-D printing. The experiments verify the correctness of analysis. The optimization methods can reduce flow resistance by 80.4% and increase heat transfer coefficient (HTC) by 44% at the same pressure. The HPr can serve as a reference for evaluating cooling structures.]]></description>
      <pubDate>Wed, 23 Apr 2025 11:54:10 GMT</pubDate>
      <guid>https://trid.trb.org/View/2511799</guid>
    </item>
    <item>
      <title>Roughness Effects on Ship Design and Operation</title>
      <link>https://trid.trb.org/View/1974252</link>
      <description><![CDATA[Hull surface condition plays an important role for ships performances for new-built ships as well as ships in operation since the drag penalties due to hull roughness are substantial. It is a standard practice that ship design is based on performance evaluation by model testing of ship models with hydrodynamically smooth surface and the increase of resistance for new build condition is added by roughness correlation allowance based on empirical formula. Surface roughness effects beyond the new build condition are seldom considered in the design process. The question is whether hull roughness affects the flow characteristics to such extend that it influence with the resulting design. This is especially important for propellers or energy saving devices which are operating around the stern of the ship where the roughness effects on flow characteristics are most pronounced.This paper will discuss some practical questions related to the effect of hull roughness, both in terms flow characteristics, power increase and impact on ship design and operational practice.]]></description>
      <pubDate>Mon, 20 May 2024 14:02:21 GMT</pubDate>
      <guid>https://trid.trb.org/View/1974252</guid>
    </item>
    <item>
      <title>Application of a New Flow Resistance Formula: Step-pool Culvert Installation</title>
      <link>https://trid.trb.org/View/2200831</link>
      <description><![CDATA[In the present study, the question of constructing a pseudo-natural step-pool streambed within a roadway culvert is examined. This is a new method, based on a geomorphology study conducted using a hydraulic model, and a formula for computing the flow resistance caused by step-pool bedforms is described. An example case is examined, and a summary of the analysis procedure is provided.]]></description>
      <pubDate>Wed, 25 Oct 2023 10:14:29 GMT</pubDate>
      <guid>https://trid.trb.org/View/2200831</guid>
    </item>
    <item>
      <title>Investigation on flow resistance of fluid in permeable asphalt mixture</title>
      <link>https://trid.trb.org/View/2208755</link>
      <description><![CDATA[Flow resistance distribution of fluid is the basis of comprehensively grasping the permeability of permeable asphalt mixture. This study aimed to investigate the flow resistance of fluid in permeable asphalt mixture. Considering the influence of anisotropy of permeable asphalt mixture, the vertical and transverse permeability tests of five types of permeable asphalt mixture were carried out using multidirectional permeability test instrument developed by the authors' research group. The fitting equation of permeability was determined by comparing Darcy's law with Forchheimer equation. Moreover, the flow resistance is usually considered as an effective parameter to reveal the structural permeability. The connective void content of permeable asphalt mixture is important to calculate flow resistance. Accordingly, it is necessary to obtain the transverse and vertical connective voids of the asphalt mixture considering the influence of anisotropy. Therefore, a program for calculating the multi-directional connective void content was developed based on the theory of projection reconstruction. On this basis, a pore throat model was applied to reveal the variation of flow resistance of asphalt mixture. The results show that the weight of inertia resistance and viscous resistance is different in various seepage velocities. The viscous resistance is dominant when the fluid flow velocity is less than 0.0087 m/s under experimental conditions, and the inertial resistance is dominant when the fluid flow velocity is greater than 0.0087 m/s. The viscous resistance and inertia resistance of fluid are affected by the anisotropy and structure type of permeable asphalt mixture. When the vertical void content decreases by 3.3%, the corresponding viscous and inertial resistance increase by 7.92 kPa/m and 0.84 kPa/m, respectively. For the transverse void, the viscous and inertial resistance increase by 3.19 kPa/m and 2.02 kPa/m respectively as the content decreases by 3.5%. The influence of void structure of permeable asphalt mixtures on fluid flow is revealed from a microscopic perspective, which can be used to guide the optimization design of gradation of permeable asphalt mixtures.]]></description>
      <pubDate>Mon, 28 Aug 2023 09:34:03 GMT</pubDate>
      <guid>https://trid.trb.org/View/2208755</guid>
    </item>
    <item>
      <title>Quantification of Effective Flow Resistivity for Parametric Assessment of Pervious Concrete by Using Ultrasonic Pulse Velocity Method</title>
      <link>https://trid.trb.org/View/2146109</link>
      <description><![CDATA[The use of nondestructive ultrasonic pulse velocity (UPV) testing to assess the hardened properties of pervious concrete (PC) mixtures is an emerging research area. Further, UPV has been successfully used to determine the effective flow resistivity (EFR) of asphalt concrete and cement concrete pavements. However, no research studies have focused on understanding PC characteristics using EFR. Thus, the major objectives of this study were to assess the suitability of UPV testing for characterizing PC mixtures and to quantify their EFR, which is a measure of the material’s characteristic impedance and is dependent on the mix variables along with porosity. Thirty-six control and sand-modified PC mixtures were prepared with four aggregate gradations, and three levels each of water-to-cement (w/c) and aggregate-to-cement (a/c) ratios. Test results indicated that EFR was significantly dependent on the mix variables, with aggregate gradation being the most influential factor (six and eight times higher than w/c and a/c ratios, respectively). Lower EFR or higher sound absorption capacity was reported for PC with higher porosities. The sand-modified PC mixtures had higher EFR (by 4%–12%) than the control PC, and consequently lower sound absorption capacity, attributed to the presence of mortar that densified the mixes. Further, good-to-excellent correlations were obtained for various PC properties with UPV and EFR, which underscored the potential of UPV in characterizing PC. The major contribution of this research was the development of a simple, fast, and cost-effective approach, which can be suitably adopted as a quality-control test to determine PC mixture properties.]]></description>
      <pubDate>Sat, 08 Apr 2023 16:08:54 GMT</pubDate>
      <guid>https://trid.trb.org/View/2146109</guid>
    </item>
    <item>
      <title>Experimental and numerical investigation of the gap flow between a pusher and a barge in deep and shallow water</title>
      <link>https://trid.trb.org/View/2110144</link>
      <description><![CDATA[The flow in the gap between a pusher boat and a barge of a conventional inland waterway convoy was experimentally and numerically investigated to gain insight into the complex flow pattern and to provide benchmark data for validation of an adequate turbulence model. Two water depths were considered, corresponding to deep water and moderately shallow water conditions. Both cases highlighted the extremely unsteady non-uniform flow pattern in the gap. The collected data were subsequently used to assess a numerical method based on solving the Reynolds-averaged Navier–Stokes (RANS) equations and the Improved Delayed Detached Eddy Simulation (IDDES) technique. Generally, the authors' numerical predictions compared favorably to the experimental data; however, the IDDES method proved to be more accurate, especially in the prediction of the velocity field in the gap region. The IDDES technique was then used to analyze the flow in water depth to draft ratios h/T of 2.14, 1.5, and 1.2. At h/T=1.2, comparatively larger recirculation zones and a massive increase in resistancfe were observed. Additionally, to quantify the influence of the gap between pusher and barge on resistance in shallow waters, they modified their model by simply covering the gap and then analyzing this modified model by carrying out an additional simulation at h/T=1.2. Covering the gap reduced the overall longitudinal hydrodynamic force acting on the convoy by about 6.5 %.]]></description>
      <pubDate>Mon, 27 Feb 2023 08:51:33 GMT</pubDate>
      <guid>https://trid.trb.org/View/2110144</guid>
    </item>
    <item>
      <title>Stability and drag reduction in turbulent flow of skin with quasi-periodic elastic supports</title>
      <link>https://trid.trb.org/View/2030589</link>
      <description><![CDATA[In order to reduce the flow resistance on the surface of ships, the skin with quasi-periodic elastic supports is designed based on the flexible skin drag reduction technology inspired by dolphin skin. In this paper, the stability characteristic equation of fluid-structure coupling system is established based on small perturbation theory and solved by MATLAB. The results indicate that the skin with quasi-periodic elastic supports has the ability of maintaining stability of turbulent boundary layer when the structural parameters are reasonable. In addition, the drag reduction performance of the skin with quasi-periodic elastic supports is studied by immersion boundary method. The analysis results demonstrate that the skin with quasi-periodic elastic supports can show better drag reduction performance than the skin with periodic elastic supports when the structural parameters q and the support spacing L are rationally set. In a certain speed range, the relative drag reduction rate is up to 72.16%. These optimal distribution parameter data of the skin under certain speed conditions obtained in this paper provide a reference for the practical application and intelligent optimization design of the skin with quasi-periodic elastic supports.]]></description>
      <pubDate>Thu, 27 Oct 2022 17:11:52 GMT</pubDate>
      <guid>https://trid.trb.org/View/2030589</guid>
    </item>
    <item>
      <title>Blockage effect influence on model-scale marine propeller performance and cavitation pattern</title>
      <link>https://trid.trb.org/View/1904480</link>
      <description><![CDATA[The blockage effect is one of the drawbacks in the use of cavitation tunnels, which may considerably interfere in the measurements of the hydrodynamics of model-scale propellers. The literature presents some methods to correct the acquired values, such as the Glauert method, but the deduction of this method does not consider the cavitation effects. This paper aims to use CFD tools to compare and analyze the effect of different levels of blockages on the thrust, torque, hydrodynamic efficiency, and cavitation on two model-scale marine propellers. Five different blockage ratios (from 1% to 41%) and three test cases are simulated, varying the advance ratio to compose the propeller performance diagram. The simulations have shown that the Glauert formula satisfactorily corrected thrust, torque, and hydrodynamic efficiency, even in moderate cavitation. When cavitation is intense, it is observed that the blockage decreases the thrust and torque, not being recommended to use the Glauert formula. It is observed that the cavitation is sensitive to blockage, and it can affect its pattern on the blade surface.]]></description>
      <pubDate>Mon, 24 Jan 2022 17:27:39 GMT</pubDate>
      <guid>https://trid.trb.org/View/1904480</guid>
    </item>
    <item>
      <title>Ship performance in ice channels narrower than ship beam: Model test and numerical investigation</title>
      <link>https://trid.trb.org/View/1884810</link>
      <description><![CDATA[During escort and convoy operations, an icebreaker opens a channel while the escorted or convoyed ships follow the path along the channel. If the assisted ship is wider than the channel which the icebreaker creates, the created channel cannot fit the assisted ship. Thus, the assisted ship has to break some ice by itself. This is herein referred to as navigation in ‘narrow ice channel’. The performance of ships in narrow ice channel is investigated here. For this aim, model-scale test of a ship going through ice channels with different widths and ice thicknesses is firstly conducted. After that, numerical simulation of the model test scenarios is implemented with an in-house simulation program dedicated for ship operation in ice. The simulation correctly captured the main features of ship resistance change as a function of channel width, which indicates its validity as a simulation tool. Subsequentially, numerical simulations are implemented with several other ships in order to gain general insights into performance of ships in narrow ice channel. Focus is given to the influence of channel width on ships' encountered resistance and attainable speed in ice. The general findings through these simulations are useful for decision making tools.]]></description>
      <pubDate>Mon, 25 Oct 2021 09:16:36 GMT</pubDate>
      <guid>https://trid.trb.org/View/1884810</guid>
    </item>
    <item>
      <title>Influence of the Timber Shape on the Aerodynamics of a Timber
                    Truck</title>
      <link>https://trid.trb.org/View/1853002</link>
      <description><![CDATA[The aerodynamic improvement and efficiency of regular goods transportation trucks                     have been a topic of current interest; however, the timber transport industry                     has not been receiving as much attention. This is due to the small portion of                     timber transportation vehicles, compared to regular trucks, not justifying the                     cost of investigating these vehicles experimentally. Since these vehicles travel                     large parts of their journey at around 80 km/h, their fuel consumption is                     heavily affected by the aerodynamic resistance. In Sweden in 2015, there were                     around 2000 vehicles in operation transporting 6 billion ton-km with an average                     of 0.025 liter Diesel per ton-km. To understand these vehicles’ aerodynamics,                     and improve on these in the future, the modelling of the timber stacks is of                     utmost importance. Computational Fluid Dynamics (CFD) simulations have been                     utilized to conduct this investigation due to recent advancements and the                     relatively low cost of these simulations compared to an experimental approach.                     By investigating the influence of geometrical modifications of the stacks on the                     flow features and accumulated drag, a generic timber stack was created                     representative of a real stack for a loaded baseline vehicle. It was found that                     the shorter log length and a shuffling of the logs in the stack exhibit                     important flow features contributing to drag not present in the other cases.                     Based on this, a new baseline loaded truck configuration was created with all                     stacks being identical to each other. This generic stack was built with logs                     that were 4.25 m long and 0.35 m in diameter, had a smooth surface, and were                     stacked with a certain displacement in the lengthwise direction.]]></description>
      <pubDate>Mon, 31 May 2021 20:20:20 GMT</pubDate>
      <guid>https://trid.trb.org/View/1853002</guid>
    </item>
    <item>
      <title>Automatic Control of Pneumatic Networks of Railway Train</title>
      <link>https://trid.trb.org/View/1838794</link>
      <description><![CDATA[Automatic brakes of rolling stock are the main means of ensuring the safety of railway trains. Failure of motor brakes or loss of braking efficiency can lead to a serious accident or train crash, so monitoring the technical condition of rolling stock braking equipment is particularly important. The current method of checking the density of the braking network does not meet the requirements of traffic safety. The article considers the method developed by the authors to automatically control the integrity and density of the braking network of the railway train, the use of which will prevent cases of departure of the train to the crossing with closed end cranes. Proposed method of comparing compressed air from pneumatic network of one car with flow rate standard. The block diagram of the device for control of the train braking network, operating in automatic mode and completely frees the locomotive crew from preparation and calculation operations related to maintenance of pneumatic networks of the railway train, is presented. In addition, a new method of determining the number of sets connected to the brake line of a railway train is described.]]></description>
      <pubDate>Mon, 26 Apr 2021 09:34:18 GMT</pubDate>
      <guid>https://trid.trb.org/View/1838794</guid>
    </item>
    <item>
      <title>Development of Two-Step Secant Method to Interpret the Flow Number Test Data of Asphalt Mixtures</title>
      <link>https://trid.trb.org/View/1686619</link>
      <description><![CDATA[The flow number test is widely utilized as a routine test for assessing the rutting resistance of asphalt mixtures. The objective of this study is to propose a novel method of determining the flow number of asphalt mixtures with better accuracy. The Dynamic Testing System (DTS) was employed to perform the flow number tests on four types of asphalt mixtures at multiple temperatures. With respect to the test data, the existing flow number calculation methods are firstly evaluated in terms of the accuracy of the determined flow number values. It is demonstrated that none of the existing methods are recommended to determine the flow number of asphalt mixtures. The two-step secant method is then developed based on the curve shape of the permanent strain versus load cycles graph. The characteristics of concavity and convexity shown in such a graph are utilized to determine the onset of the secondary stage and that of the tertiary stage. As the kernel of the two-step secant method, the secant method is employed twice to determine the load cycle at the minimum slope of secant line for selected permanent strain data. The two load cycles determined by the second step of the two-step secant method are demonstrated to be the onset of the secondary stage and tertiary stage. The termination criterion of flow number tests is then established based on the test data of four asphalt mixtures so that the two-step secant method can be applicable. In conclusion, the proposed two-step secant method is capable of determining the initiation points of the secondary stage and tertiary stage with better accuracy for different types of asphalt mixtures.]]></description>
      <pubDate>Fri, 28 Feb 2020 10:11:20 GMT</pubDate>
      <guid>https://trid.trb.org/View/1686619</guid>
    </item>
    <item>
      <title>Growth and Restructuring Phenomena of Deposits in Particulate Filters</title>
      <link>https://trid.trb.org/View/1561560</link>
      <description><![CDATA[As use of Particulate Filters (PFs) is growing not only for diesel but also for gasoline powered vehicles, the need for better understanding of deposit structure, growth dynamics and evolution arises. In the present paper we address a number of deposit growth and restructuring phenomena within particulate filters with the aim to improve particulate filter soot load estimation. To this end we investigate the dynamic factors that quantify the amount of particles that are stored within the wall and the restructuring of soot deposits. We demonstrate that particle accumulation inside the porous wall is dynamically controlled by the dimensionless Peclet number and provide a procedure for the estimation of parameters of interest such as the loaded filter wall permeability, the wall-stored soot mass at the onset of cake filtration. Restructuring phenomena affecting the flow resistance of soot deposits are identified and a novel mathematical model of describing a cracked deposit is developed and validated against experimental data. Overall, the better understanding of such phenomena can lead to improved on-board model based control of emission control systems.       ]]></description>
      <pubDate>Mon, 10 Feb 2020 09:08:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/1561560</guid>
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