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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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    <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>Optimization of aerodynamic performance by applying the combination of lamellar and 3D wheel deflectors on the SUV model</title>
      <link>https://trid.trb.org/View/2521790</link>
      <description><![CDATA[In the developmental phase of an electric SUV model, optimizing the SUV model’s aerodynamic performance often involves the use of wheel deflectors to control airflow around the front wheels. While lamellar wheel deflectors are a common choice for reducing aerodynamic drag, the automotive industry is increasingly embracing 3D wheel deflectors to enhance drag reduction efforts. This study delves into the flow patterns surrounding the front wheels and the drag reduction mechanisms brought about by wheel deflectors. In this research, the authors harness the strengths of both lamellar and 3D wheel deflectors to introduce a more effective design approach. The conceived wheel deflectors aim to simultaneously decrease aerodynamic drag and lift, a dual-purpose strategy that extends the SUV’s range and optimizes its stability at high speeds. To validate these optimization effects, comprehensive Computational Fluid Dynamics (CFD) simulations and subsequent wind tunnel testing are conducted. The findings presented in this paper establish a crucial foundation for the design and optimization of wheel deflectors, contributing to advancements in the field.]]></description>
      <pubDate>Fri, 21 Mar 2025 09:03:38 GMT</pubDate>
      <guid>https://trid.trb.org/View/2521790</guid>
    </item>
    <item>
      <title>Quality Assurance Procedures for Traffic Speed Deflection Devices</title>
      <link>https://trid.trb.org/View/2381723</link>
      <description><![CDATA[In recent years, significant progress has been made in the development of traffic speed deflection devices (TSDDs), with over 20 systems in use globally. In the United States, these devices have gained interest among state departments of transportation (DOTs) due to their ability to collect pavement structural condition data at the network level while operating at traffic speed. As a result, many state DOTs have begun collecting this data to explore its use in pavement management and design applications. However, there are no nationally accepted quality assurance (QA) procedures for TSDDs, and the QA procedures used for falling weight deflectometers cannot be directly applied to them.
As more state DOTs rely on TSDD data for pavement management and design, the lack of standardized QA procedures for measuring and interpreting this data can lead to inaccurate decision-making and improper maintenance strategies. There is a need for a practical, standardized approach to QA for TSDD data that can be applied across various use cases.
OBJECTIVE: The objective of the project is to develop device-independent QA procedures for TSDD data, addressing the challenges posed by its dynamic moving load. These procedures shall address the accuracy, precision, repeatability, and reproducibility of TSDD data used in pavement assessments.
]]></description>
      <pubDate>Tue, 21 May 2024 17:12:42 GMT</pubDate>
      <guid>https://trid.trb.org/View/2381723</guid>
    </item>
    <item>
      <title>Aerodynamic Analysis of Heavy-Duty Vehicles Using Computational Fluid Dynamics Approach</title>
      <link>https://trid.trb.org/View/2096120</link>
      <description><![CDATA[Fuel consumption of heavy-duty vehicles (HDV) is one of the major challenges in the automotive industry. In recent days, gasoline prices have been raised high, so the HDVs need to be designed to be more fuel-efficient. Many studies reported that aerodynamic optimization is one of the most important advancements in terms of fuel-efficient HDVs. The computational fluid dynamics (CFD) tool or approach is widely accepted for aerodynamic analysis. This study identifies the flow zones with the large pressure drag and design parameters, incorporating appropriate geometric changes into the design. The computational results show that the drag reduction of individual devices in cab and trailer is 15.9%. The cab deflector and boat tails are the most effective individual geometry and successfully reduce the drag up to 20%.]]></description>
      <pubDate>Mon, 09 Jan 2023 16:58:59 GMT</pubDate>
      <guid>https://trid.trb.org/View/2096120</guid>
    </item>
    <item>
      <title>A comparative study of tail air-deflector designs on aerodynamic drag reduction of medium-duty trucks</title>
      <link>https://trid.trb.org/View/1948208</link>
      <description><![CDATA[With the rapid development of highway networks and logistics industry in China, medium-duty trucks have been increasingly used for highway and urban area freight transportation. The aerodynamic drag reduction of medium-duty trucks is of significant importance for improving highway transportation efficiency, enhancing fuel economy, and reducing greenhouse emissions. This paper proposes, compares and evaluates seven designs of tail air-deflector, which are devised to reduce aerodynamic drag of a medium-duty truck. The impacts of the shapes and/or configurations of tail air-deflector on the aerodynamic characteristics of the truck are studied using computational fluid dynamics (CFD) simulation. The results attained from the comparative study will provide guidelines for the design of airflow control devices for commercial vehicles to effectively reduce aerodynamic drag.]]></description>
      <pubDate>Tue, 24 May 2022 10:05:05 GMT</pubDate>
      <guid>https://trid.trb.org/View/1948208</guid>
    </item>
    <item>
      <title>The influence of wind deflectors on the snow distribution in road cuttings during snowdrift</title>
      <link>https://trid.trb.org/View/1909779</link>
      <description><![CDATA[The prevention and control of wind-induced snow disasters in traffic lines are significant for ensuring traffic operation in high-latitude, cold areas. Many unsolved problems still exist due to the complicated mechanism of snowdrift formation. Wind-guiding measures may effectively reduce drifting snow disasters in traffic lines. By using computational fluid dynamics (CFD), the effects of three wind deflectors (vertical, backward, and forward types) on wind-induced snow accumulation in a typical cutting are discussed. The authors analyze the effect of the wind deflector on reducing snow deposition in terms of the flow field, deposition length, and snow facies concentration. The results show that the inclination angle of the wind deflector is a key parameter that affects snow disaster prevention. It is recommended that a forward-inclined wind deflector should be selected in practice, and the angle between the wind deflector and vertical axis should be controlled at approximately 45°.]]></description>
      <pubDate>Mon, 28 Feb 2022 09:40:56 GMT</pubDate>
      <guid>https://trid.trb.org/View/1909779</guid>
    </item>
    <item>
      <title>Analysis of Aerodynamic Performance of a High Energy Efficiency Prototype</title>
      <link>https://trid.trb.org/View/1827102</link>
      <description><![CDATA[This paper presents a study developed in order to improve the aerodynamic performance of an automotive prototype by means of simulations carried out by a software that makes of the finite volume method. The prototype will be built at the Laboratory of Automotive Engineering of the Lutheran University of Brazil - ULBRA. Taking into account the original design of the automotive prototype, three virtual models were generated and analyzed. There were three steps to simulate the aerodynamic behavior on a 3D model: generation of the geometry with the employment of CAD software, generation of the mesh for the faces and volume that involve the car, using specific software, and solving the flow, with a CFD software. The results of the analysis allowed identifying the model with the lowest aerodynamic drag. That model had some modifications on its design, when compared to the original one, like wheels and their housings. Also, an air deflector was included on the back of the virtual prototype, in order to reduce the drag. The results obtained were reasonable, because of the deflector, which gave a drag reduction around of 6%.]]></description>
      <pubDate>Thu, 09 Dec 2021 10:35:15 GMT</pubDate>
      <guid>https://trid.trb.org/View/1827102</guid>
    </item>
    <item>
      <title>Development of a Cost Effective Power Train Cooling System for a Passenger Car with Rear Engine</title>
      <link>https://trid.trb.org/View/1817574</link>
      <description><![CDATA[The present automobile era in India is driven by development of small size and low cost ‘value for money’ cars. Proper utilization of space and low cost engineering of the vehicle aggregates plays a key role for attaining the goal of low cost-small cars. This paper illustrates the development of power train cooling system of such cost sensitive passenger car with rear engine and rear mounted heat exchangers.         The major obstacle for the power train cooling system of rear engine-rear mounted heat exchanger (radiator) is absence of ram air effect at higher vehicle speeds and air temperatures higher then ambient, as observed for front mounted heat exchanger. The subject vehicle encountered power train cooling system failure at max speed operating condition and the project timeline required a quick solution without any major modifications and cost escalation.         In case of subject vehicle because of its packaging, the air flow rate for heat exchanger was fully dependent of fan capacity. However, at higher vehicle speeds there was an opportunity to boost the air flow rate by proper air management within vehicle boundaries. After DOE and CFD analysis, an air deflector was introduced at the bottom of heat exchanger which improved the heat transfer rate by utilizing the high velocity air underneath the vehicle.]]></description>
      <pubDate>Thu, 09 Dec 2021 10:33:29 GMT</pubDate>
      <guid>https://trid.trb.org/View/1817574</guid>
    </item>
    <item>
      <title>CFD Application in Automotive Front-End Design</title>
      <link>https://trid.trb.org/View/1806962</link>
      <description><![CDATA[The front-end design process in the automotive industry today is time consuming and expensive. Although CFD (Computational Fluid Dynamics) modeling is helpful, many vehicle development tests in different wind tunnels are still required to balance the competing requirements of power train cooling, vehicle aerodynamics, climate control, styling, body structure, and product cost. For example, engine cooling and climate control heat exchangers require adequate airflow to achieve their performance. But, this airflow increases cooling drag and can compromise vehicle handling. Internal air deflectors (ducting) are often used to make the frontal opening more efficient and help prevent heat recirculation from the hot engine compartment to the A/C condenser at idle. But this increases product cost and can compromise underhood temperature. A more efficient and faster process is needed to support these trade-off discussions.         The objective of this report is to examine the suitability of using one CFD model to address this need. One front-end CFD model is used for all three attributes: power train cooling, thermal re-circulation at idle and cooling drag. The focus is on SUV and Pickup Trucks with mechanical fans. The following parameters are investigated: fan speed, engine heat rejection, and air deflector (air ducting) impact on recirculation. Overall, the CFD quantitative results look very reasonable and offer the promise of improving the product development process. The qualitative flow field and temperature contour maps were very helpful to the understanding of the results.]]></description>
      <pubDate>Thu, 09 Dec 2021 10:26:33 GMT</pubDate>
      <guid>https://trid.trb.org/View/1806962</guid>
    </item>
    <item>
      <title>The Impact of Design, Position and Combination of Aerodynamic Devices on Drag and Fuel Consumption</title>
      <link>https://trid.trb.org/View/1779356</link>
      <description><![CDATA[The performance of several aerodynamic technologies and approaches, such as trailer skirts, trailer boat tails, gap reduction, was evaluated using track testing, model wind tunnel testing, and CFD simulation, in order to assess the influence of the design, position and combination of various aerodynamic devices.         The track test procedure followed the SAE J1321 SAE Fuel Consumption Test Procedure - Type II. Scale model wind tunnel tests were conducted to have direct performance comparisons among several possible configurations. The wind tunnel tests were conducted on a 1/8 scale model of a tractor in combination with a 53-foot semi-trailer. Among others, the wind tunnel tests and CFD simulations confirmed the influences of trailer skirts' length observed during the track tests and that the wider skirt closer to the ground offer better results. The differences in the shape, dimensions and position of rear deflectors and trailer skirts on the trailer are reflected in the test results. Track testing and CFD simulation confirmed that the approach to reduce the tractor-trailer gap can result in improved fuel efficiency.         The tests showed that combinations of aerodynamic devices can bring additional benefits. The results obtained by combining trailer skirts and trailer rear deflectors are better than those obtained by the trailer skirts or gap deflector alone. This can be explained by the additional reduction in aerodynamic drag at the rear of the trailer, or in the gap between the tractor and trailer.]]></description>
      <pubDate>Mon, 03 May 2021 11:49:04 GMT</pubDate>
      <guid>https://trid.trb.org/View/1779356</guid>
    </item>
    <item>
      <title>Environmental Influences on the Curling of Concrete Slabs at the Palmdale HVS Test Site</title>
      <link>https://trid.trb.org/View/1751190</link>
      <description><![CDATA[The main objective of this series of tests was to investigate the influence of daily temperature variations on the curling of concrete slabs at the edges and corners, and the horizontal opening of joints between slabs in eight HVS tests sections, both with and without the influence of the temperature control chamber. To isolate the effect of temperature, none of the test sections was subjected to HVS loading during this investigation. All readings were taken while the HVS wheel was stationary and raised above the concrete slabs. The second objective was to study the effectiveness of dowels and tie bars in restricting vertical movement and transverse joint opening under the influence of daily temperature fluctuations, and the effect of a 4.3-m versus 3.7-m slab width on the same movements. As with the first objective, the test sections were not subjected to HVS loading during this part of the study.]]></description>
      <pubDate>Mon, 26 Apr 2021 15:14:45 GMT</pubDate>
      <guid>https://trid.trb.org/View/1751190</guid>
    </item>
    <item>
      <title>Numerical Characterization of Brake System Cooling, Aerodynamic, and Particle Soiling Performances under Driving Conditions</title>
      <link>https://trid.trb.org/View/1745904</link>
      <description><![CDATA[Effective cooling of a heated brake system is critical for vehicle safety and reliability. While some flow devices can redirect airflow more favorably for convective cooling, such a change typically accompanies side effects, such as increased aerodynamic drag and inferior control of brake dust particles. The former is critical for fuel efficiency while the latter for vehicle’s soiling and corrosion as well as non-exhaust emissions. These competing objectives are assessed in this study based on the numerical simulations of an installed brake system under driving conditions. The thermal behavior of the brake system as well as aerodynamic impact and brake dust particle deposition on areas of interest are solved using a coupled 3D transient flow solver, PowerFLOW. Typical design considerations related to enhanced brake cooling, such as cooling duct, wheel deflector, and brake air deflector, are characterized to evaluate the thermal, aerodynamic and soiling performance targets. The leading mechanisms relating the changes in cooling airflow and their impact on performance are discussed. In addition, parametric sensitivity and interactions are analyzed in the design scenario. The proposed approach can be leveraged to evaluate the complex design trade-offs for a brake system in any development stage without the need for a physical model or testing.]]></description>
      <pubDate>Tue, 17 Nov 2020 18:51:33 GMT</pubDate>
      <guid>https://trid.trb.org/View/1745904</guid>
    </item>
    <item>
      <title>Maneuverability analysis of thrust vectoring ducted propeller with deflector</title>
      <link>https://trid.trb.org/View/1727644</link>
      <description><![CDATA[A thrust vectoring ducted propeller with deflector is a new method for vector propulsion that produces lateral forces and torques and manipulates the autonomous underwater vehicle (AUV) for various movements. In this work, the geometric model of the thrust vectoring ducted propeller is designed. The six degree of freedom (DOF) kinematic and dynamic model of a cylinder-shaped AUV equipped with the thrust vectoring ducted propeller is developed based on Newton's equation and Euler's equation considering the forces and torques generated by the ducted propeller with deflector. The performance of the ducted propeller is evaluated using Computational Fluid Dynamic (CFD) method. The simulation of pitch motions, yaw motions, pitch and yaw coupled three-dimensional motions and maneuverability analysis are carried out based on the kinematic and dynamic model. The simulation results demonstrate that thrust vectoring ducted propeller with deflector can achieve accurate control on depth, pitch and yaw angle, and has good maneuverability on three-dimensional motion control.]]></description>
      <pubDate>Tue, 29 Sep 2020 09:58:45 GMT</pubDate>
      <guid>https://trid.trb.org/View/1727644</guid>
    </item>
    <item>
      <title>A numerical investigation on the improvement of anti-snow performance of the bogies of a high-speed train</title>
      <link>https://trid.trb.org/View/1727453</link>
      <description><![CDATA[In this paper, numerical simulations combining unsteady Reynolds-averaged Navier-Stokes (URANS) simulation and the discrete phase model are used to study the application of countermeasure for snow accumulation in the regions of bogie cavities of a high-speed train. The influence of the cowcatcher heights and guide structure configurations on the flow features and snow accumulation was studied. The results of the study show that the cowcatcher with a downward elongation of 4% of the distance between the two axles decreases the snow accumulation in the first and the second bogie regions by about 56.6% and 13.6%, respectively. Furthermore, the guide structures have been found to significantly alter the velocity and pressure distribution in the second bogie region, resulting in a relatively large snow-accumulation reduction. The deflector is found to perform better in reducing snow accumulation when compared to the diversion slots. The cowcatcher, elongated in the downward direction, and the deflector proved to be a good countermeasure for snow accumulation around the bogies of high-speed trains operating in snowy weather conditions.]]></description>
      <pubDate>Fri, 11 Sep 2020 17:31:21 GMT</pubDate>
      <guid>https://trid.trb.org/View/1727453</guid>
    </item>
    <item>
      <title>Method for Preventing Contamination on Trucks Cabin Side Using CFD</title>
      <link>https://trid.trb.org/View/1560342</link>
      <description><![CDATA[Although ignored by most people not directly involved with highway and off-road commercial trucks operation the accumulation of dust and mud on cabin side can become a rather annoying issue. Besides adhering to the passengers clothes dirt contamination may also compromise driver visibility constituting a safety concern. For a truck manufacturer it can revert into quality complaints and negatively influence customers’ future buying decisions. In this context, fascia air deflectors are common devices used in truck industry to control the airflow over the cabin panels and ultimately prevent contamination deposition. This paper presents a methodology to avoid dust and mud accumulation on commercial trucks cabin doors based on the predicted airflow field by computational fluid dynamics (CFD) and a reference flow metric defined through a simple bench test. Comparing the results of the CFD analysis with an experimental study it is demonstrated that without resorting to costly wind tunnel tests or complex and computationally demanding Eulerian or Lagrangian multiphase simulations the proposed methodology ensures consistent results for tuning a deflector design to effectively prevent dirt accumulation. Soling simulations have also been performed as an add-on for further assessing the design directions provided by the method.       ]]></description>
      <pubDate>Thu, 23 May 2019 10:24:43 GMT</pubDate>
      <guid>https://trid.trb.org/View/1560342</guid>
    </item>
    <item>
      <title>Aeroelastic Response and Structural Improvement for Heavy-Duty Truck Cab Deflectors</title>
      <link>https://trid.trb.org/View/1601378</link>
      <description><![CDATA[Numerical simulations on the fluid-structure interaction were conducted using commercial software STAR-CCM+ and ABAQUS. The aeroelastic responses of a deflector under several different working conditions were simulated utilizing finite volume and finite element methods to investigate the aeroelastic problem of automotive deflectors. Results showed that the structural response of a top deflector is minimal under the influence of aerodynamics given its large structural stiffness. The size of the top deflector was optimised by using thickness as a variable. The volume and quality of the top deflector were significantly reduced, and its lightweight performance was improved to satisfy the stiffness performance requirement. The vibration of a side deflector structure was mainly induced by the turbulence on the structure surface. The amplitude of vibration was small and the vibration gradually converged in a few seconds without obvious regularity. Six structures were constructed to reduce the deformation of the side deflector structure and improve the noise, vibration and harshness performance of the heavy-duty truck. Five of these structures significantly reduced the elastic response of the side deflector.       ]]></description>
      <pubDate>Mon, 29 Apr 2019 09:24:38 GMT</pubDate>
      <guid>https://trid.trb.org/View/1601378</guid>
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