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    <title>Transport Research International Documentation (TRID)</title>
    <link>https://trid.trb.org/</link>
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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>
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      <link>https://trid.trb.org/</link>
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    <item>
      <title>THE STRUCTURE OF A THREE-DIMENSIONAL TIP VORTEX AT HIGH REYNOLDS NUMBERS</title>
      <link>https://trid.trb.org/View/406511</link>
      <description><![CDATA[The tip vortex structure of a three-dimensional hydrofoil at high Reynolds number was measured experimentally in both the 48-inch (1.22m) diameter water tunnel and the 48-inch (1.22m) wind tunnel at the Applied Research Laboratory at the Pennsylvania State University. The flow on and near the hydrofoil was studied using a number of flow visualization techniques, laser velocimetry (tip boundary layers) and pressure taps.  The downstream tip vortex was measured with a three-component laser velocimeter at a number of streamwise positions with a detailed planar mapping of the flow in the region of cavitation inception. These experiments and measurements, which include flow visualization, were conducted to investigate the tip vortex structure flowfield and its relationship to cavitation inception. The effect of the Reynolds number and applied tip roughness on the downstream tip vortex and the influence of the unsteady pressure fluctuations in the core on cavitation inception were investigated. Results of these flowfield experiments are analyzed and conclusions are presented.]]></description>
      <pubDate>Thu, 21 Jul 1994 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/406511</guid>
    </item>
    <item>
      <title>THE STRUCTURE OF TIP VORTICES OVER A RANGE OF CAVITATION NUMBER</title>
      <link>https://trid.trb.org/View/406512</link>
      <description><![CDATA[The tip vortex roll-up process resulting from the flow about an elliptic wing was experimentally investigated. Cavitation conditions provided an excellent means for visualizing the mechanism of vortex roll-up. The velocity profiles of the noncavitating vortex were first obtained with a laser Doppler velocimeter. The measured asymmetry of the velocity profile and the computed pressure distribution in the vortex core were determined. In the case of fully developed cavitation, the vortex trajectory was analyzed and compared with theory. It was found that the cavity core radius increases as pressure is reduced, until the developed cavity forms a twisted ribbon structure. Also discussed are the effects of core thickness and wave length on tip vortex flow.]]></description>
      <pubDate>Thu, 21 Jul 1994 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/406512</guid>
    </item>
    <item>
      <title>SIMULATION OF SHIP WAKES IN WATER TUNNEL CAVITATION TESTING OF MODELS</title>
      <link>https://trid.trb.org/View/406513</link>
      <description><![CDATA[Reliable cavitation testing of ship propulsors requires accurate modeling of the ship wake velocity field. This paper represents a progress report on efforts at the David Taylor Research Center (DTRC) to generate properly shaped velocity patterns in a water tunnel by means of partial length afterbody models. A survey of references is presented on the general topic of applications and techniques of wake simulation in water tunnels using a variety of means, including screens mounted normal to the tunnel stream; partial length (dummy model) hull representations; and full length geometrically scaled hull models. Described are three recent wake- generating bodies purposely designed for experiments conducted in the DTRC 36-inch Variable Pressure Water Tunnel. The wakes of these examples are taken in order of increasing degree of difficulty. In each case, there is a discussion of the target wake, the body design considerations, and the quality of the resultant simulated wake.]]></description>
      <pubDate>Thu, 21 Jul 1994 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/406513</guid>
    </item>
    <item>
      <title>SCALING PROBLEMS OF DYNAMIC MOTIONS IN WAVES FROM MODEL TESTS OF SURFACE EFFECT SHIPS AND AIR CUSHION VEHICLES</title>
      <link>https://trid.trb.org/View/406514</link>
      <description><![CDATA[The scarcity of motion response scaling data presents an accuracy problem for model tests of surface effect ships and other air cushion vehicles.  under The dominant influence of ambient atmospheric pressure to the model's data is shown, with results considered in terms of both steady state and transient response characteristics. Special model test procedures that attempt to overcome this problem are discussed, together with final recommended procedures for use in predicting full-scale behavior.]]></description>
      <pubDate>Thu, 21 Jul 1994 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/406514</guid>
    </item>
    <item>
      <title>PRESSURE PANEL DESIGN AND APPLICATION FOR THE MEASUREMENT OF WAVE IMPACTS</title>
      <link>https://trid.trb.org/View/406515</link>
      <description><![CDATA[The design of high performance ships (SES, Hydrofoil, SWATH) frequently involves the determination of secondary (wave impacts) loads. An inability to accurately determine wave impact pressures necessitates model testing to provide this information. Conventional pressure transducers that sense pressure over a small area do not accurately measure the load experienced by a panel/grillage combination. This paper illustrates and describes a transducer that models the stiffness, area and dynamic characteristics of the structure in question. Use of these data enables accurate, scaled measurement of structural responses to wave impacts. From the responses of these statically calibrated panels/grillages, equivalent uniform static pressures can be directly measured so as to provide secondary load design criteria.]]></description>
      <pubDate>Thu, 21 Jul 1994 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/406515</guid>
    </item>
    <item>
      <title>SEAKEEPING TESTS ON A SEMISUBMERSIBLE MOORED IN THE ENVIRONMENTS OF WIND, WAVES AND CURRENTS</title>
      <link>https://trid.trb.org/View/406516</link>
      <description><![CDATA[A 1:45 scale model of a moored, six-column, semisubmersible floating production system was tested in the simulated environment of waves, wind and current to determine motions and mooring forces. The model mooring system was designed to model horizontal stiffness only, and hydrodynamic effects on the mooring lines were assumed to be negligible. Both regular and irregular waves were generated for the test program. Wind was simulated using a bank of twelve analog- controlled fans. Two gusting spectra were simulated by fluctuating the fan speeds. Currents were produced in the tank using two rows of nozzles positioned one above the other below the still-water surface. The vessel was subjected to three separate environments. The two irregular wave spectra were then run with wind and current data added to the parameters. Test results were compared to those predicted by a computer program based on the traditional 3- dimensional source distribution technique using an idealized wetted hull surface of 576 panels. A comparison between the measured and computed results was made with respect to first-order oscillatory motions, second-order drift displacements and mooring forces.]]></description>
      <pubDate>Thu, 21 Jul 1994 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/406516</guid>
    </item>
    <item>
      <title>THE EFFECTS OF REYNOLDS NUMBER, SECTION SHAPE, AND TURBULENCE STIMULATION ON THE LIFT OF A SERIES OF MODEL CONTROL SURFACES</title>
      <link>https://trid.trb.org/View/406517</link>
      <description><![CDATA[A series of model control surfaces with equal areas but varying aspect ratio was tested in a towing tank on a groundboard. The size of the fins, approximately three inches span and two inches chord, is typical of control surfaces used on models that are about five feet long. Lift and drag on the fins were measured over a range of angles of attack of 0 to 35 degrees. The tests covered a range of chord-based Reynolds numbers between 42,000 and 150,000. Two sets of fins were tested, one having flat-plate sections and the other having NACA 0015 sections. The fins were each tested with and without turbulence stimulation in the form of tape with a serrated leading edge placed at 5% of the local chord aft of the leading edge of the foil. The study has shown that the lift of the NACA 0015 fins was insensitive to Reynolds number in the range of the tests, and that the lift rates compare well with the results of previous tests carried out at high Reynolds numbers. Differences were noted in the characteristics of flat-plate and NACA 0015 fins, which would indicate that the use of flat plates in the place of foil-shaped fins to save model construction cost is not a good practice. Turbulence trips increased the measured drag, as expected, but also reduced the lift rate, most noticeably on the flat-plate fins.]]></description>
      <pubDate>Thu, 21 Jul 1994 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/406517</guid>
    </item>
    <item>
      <title>SWATH RESISTANCE IN WAVES WITH ASSOCIATED STEADY AND DYNAMIC RESPONSES</title>
      <link>https://trid.trb.org/View/406518</link>
      <description><![CDATA[A series of tank tests was conducted to compare the hydrodynamic performances of single- and twin-strut SWATH models with forward speeds.  The obtained measurements include the added resistance in regular head waves of frequency of 0.3 to 1.6 Hz, together with associated dynamic responses (heaving, pitching and surging) and steady responses (sinkage and trim). Stationary tests were performed to measure the motion responses for the two models in head, quartering and beam seas.  Measurements of the bending moment at the cross deck midsection of both models in beam seas were taken. Some of these hydrodynamic properties for both models are compared with the computational results based on a 3-D diffraction theory. The main purpose of this paper is to compare the hydrodynamic performance of single- and twin-strut SWATH ships, and the results are presented.]]></description>
      <pubDate>Thu, 21 Jul 1994 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/406518</guid>
    </item>
    <item>
      <title>RELATING TRAILING VORTEX CAVITATION INCEPTION TO SINGLE PHASE FLOW MEASUREMENTS</title>
      <link>https://trid.trb.org/View/406951</link>
      <description><![CDATA[The single phase and cavitating tip vortex shed by a NACA 66-209 rounded tip hydrofoil is studied. Single phase measurements of instantaneous flow velocity are made by taking double pulsed holograms of microbubbles moving in and around the vortex core. The tailored air bubble technique of Ooi and Acosta (1983) is employed to measure both the mean and fluctuating single phase vortex core static pressure. Cavitation inception data are determined by visual inspection. The flow in the vortex core is shown to be highly unsteady. The r.m.s. axial velocity fluctuation can be as high as 0.2U sub infinity. Core pressure fluctuations are found to be greater than the freestream dynamic pressure. With saturated water, inception occurs at mean core pressures above the vapor pressure. The rapid establishment of fully developed trailing vortex cavitation when the cavitation number is reduced below inception is attributable to the small variation in mean core pressure with downstream distance. The inception index is shown to decrease dramatically with decreasing dissolved air content.]]></description>
      <pubDate>Thu, 21 Jul 1994 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/406951</guid>
    </item>
    <item>
      <title>THE INFLUENCE OF SURFACE CAVITATION ON HYDRODYNAMIC FORCES</title>
      <link>https://trid.trb.org/View/406952</link>
      <description><![CDATA[A cambered two-dimensional NACA 66 (MOD) wing section was tested in a high-speed water tunnel. Two types of cavitation, leading edge sheet and midchord transient streak cavitation, were investigated. Lift, drag and pressure coefficients were measured concurrently with cavitation observations. A method for measuring surface pressure in transient cavities was successfully developed and is discussed in the text. In a partial cavity flow, the pressure coefficients measured in the wetted region of the foil away from outside the cavity were found to coincide with the pressure measurements in a fully wetted flow condition. A significant increase in lift with increasing cavity length was measured.  The lift, however, started to fall off when the cavity length reached about 83 percent of the chord. The occurrence of midchord transient cavities was accompanied by a significant drop in lift and an increase in drag. The influence of surface cavitation on the two-dimensional foil force was found to exhibit a strong similarity to propeller thrust breakdown and thrust enhancement as measured by Emerson and Sinclair.]]></description>
      <pubDate>Thu, 21 Jul 1994 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/406952</guid>
    </item>
    <item>
      <title>ANALYSIS METHODS FOR EVALUATING MOTIONS AND ACCELERATIONS OF PLANING BOATS IN WAVES</title>
      <link>https://trid.trb.org/View/406953</link>
      <description><![CDATA[The oscillation averaging leading to the 1/m-th highest statistic has been the dominant method used in the design of planing boats and in experimental seakeeping studies. In this paper, it is shown that this concept introduces a subjective element to the calculation of the statistics and makes difficult the comparison and pooling of experimental data. In addition, the method is shown to ignore vast amounts of information about the time history that could be relevant to the performance factors. This presentation also discusses the weaknesses of the peak-trough analysis and suggests alternative measures of motion and acceleration response. These measures include the use of design data on RMS deviation, skewness, kurtosis of the raw data, and probability levels. The paper ends with a call to ship designers for more discussions on the relevant hydrodynamic data and advanced techniques necessary for more mission- and cost-effective planing boat design.]]></description>
      <pubDate>Thu, 21 Jul 1994 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/406953</guid>
    </item>
    <item>
      <title>A MATRIX DATA BASE APPROACH TO PLANING CRAFT RESISTANCE MODEL EXPERIMENTS</title>
      <link>https://trid.trb.org/View/406954</link>
      <description><![CDATA[A matrix database approach to the modeling of a planing craft thrustline in towing tank resistance experiments is presented. The matrix database approach does not actually attempt to model a specific thrustline geometry in the towing tank. Instead, a matrix of drag and running trims for a discrete range of model weights on water and longitudinal centers of gravity are obtained experimentally with a model fixed in surge, and free in pitch and heave. This matrix is then curve fitted and the desired thrustline conditions are either interpolated or extrapolated from the experimentally derived database. This method provides not only the performance information for the desired ballast and thrustline condition, but also the ability to estimate performance over a fairly large range of gross vehicle weights, longitudinal centers of gravity, and thrustline geometries. The matrix data base approach is a potential alternative to the classical modeling techniques used at present. In other classical approaches, only planing performance for the desired thrustline geometry and loading is obtained. By comparison, greater efficiency in obtaining design information for the planing craft design process results from utilizing the matrix database technique.]]></description>
      <pubDate>Thu, 21 Jul 1994 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/406954</guid>
    </item>
    <item>
      <title>A CURRENT VIEW ON SEA ICE MODELLING</title>
      <link>https://trid.trb.org/View/406955</link>
      <description><![CDATA[A brief history of the development of ice modeling techniques emhasizing the various types of model ice is given. A comparison is then made of the values of the physical properties of model ice as against actual sea ice.  For a typical model test, in which the geometric scale factor equals 30, the mechanical properties of all of the different model ices are tabulated. For many of these ices, data have not been published. It is shown that only columnar grained ice can correctly model situations where compression is important. Some current concerns of ice modeling are discussed, but lack of good quality full-scale data makes an objective comparison between model and full-scale ice difficult.]]></description>
      <pubDate>Thu, 21 Jul 1994 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/406955</guid>
    </item>
    <item>
      <title>A PRELIMINARY INVESTIGATION OF MODEL ICE FAILURE PATTERN AND PIECE SIZE GENERATED BY AN ICEBREAKER BOW FORM</title>
      <link>https://trid.trb.org/View/406956</link>
      <description><![CDATA[Icebreaking pattern and piece size is studied by photographing the breaking pattern in EG/AD model ice after the icebreaker model has been stopped and has backed up. The ice pieces broken by the bow float to the surface and its breaking pattern is illustrated. Three different scale models of the R-Class icebreaker have been tested (1:40, 1:20, 1:8), as well as a 1:22.5 scale model of the icebreaker KIGORIAK. The data from these tests are compared to the available full-scale data. Comparisons show a realistic breaking pattern in the model ice, but nondimensionalized piece sizes are larger than those in full scale.  Cracks in the model ice pieces indicate a smaller piece size, but this is prevented by what is believed to be a high residual strength in the model ice.]]></description>
      <pubDate>Thu, 21 Jul 1994 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/406956</guid>
    </item>
    <item>
      <title>CHAOTIC DYNAMICS IN CONTINUOUS-MODE ICEBREAKING</title>
      <link>https://trid.trb.org/View/406957</link>
      <description><![CDATA[Presented in this paper are the results of an exploratory study on the application of chaos theory to continuous-mode icebreaking by a towed model-scale icebreaker hull. An overview of chaos theory is given and includes brief discussions on dissipative systems, chaotic dynamics, strange attractors and fractal dimensions. The present study seeks to determine, by means of chaos theory, whether continuous-mode icebreaking should indeed be characterized as being intrinsically stochastic, and then to assess what insight could be gained by application of chaos theory to continuous-mode icebreaking. Based on the results, it is quite evident that continuous-mode icebreaking by a towed hull comprises a chaotic- dynamic system of comparatively low dimension. Other implications of the results are discussed.]]></description>
      <pubDate>Thu, 21 Jul 1994 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/406957</guid>
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