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    <title>Transport Research International Documentation (TRID)</title>
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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>Howling of a Model-Scale Nozzle Due to Shock-Induced Boundary-Layer Separation at Its Exit</title>
      <link>https://trid.trb.org/View/2688755</link>
      <description><![CDATA[The jet from a model-scale, internally mixed nozzle produced a loud howling when operated at jet Mach numbers between 0.80 and 1.00. Discrete tones dominated the noise radiated to the far field and powerful oscillations were present in the jet. To explain these observations, this paper leverages a blend of experimental acoustic and flow measurements and modal analyses thereof via the spectral proper orthogonal decomposition, computational fluid dynamics simulations and local, linear stability analyses of vortex-sheet models for the flow inside the nozzle. This blend of experiments, computations and theory makes clear the cause of the howling, what sets its characteristic frequency and how it may be suppressed. The flow around a small-radius, convex bend just upstream of the final-nozzle exit led to a pocket of locally supersonic flow that was terminated by a shock. The shock was strong enough to separate the boundary layer, but neither the attached nor separated states were stable. A periodic, shock-induced separation of the boundary layer resulted, and this shock-wave/boundary-layer interaction coupled with a natural acoustic mode of the nozzle’s interior in a feedback phenomenon of sorts. Acoustic tones and large flow oscillations were produced at the associated natural frequency of the nozzle’s interior.]]></description>
      <pubDate>Mon, 13 Apr 2026 16:48:11 GMT</pubDate>
      <guid>https://trid.trb.org/View/2688755</guid>
    </item>
    <item>
      <title>Spectral Proper Orthogonal Decomposition of Harmonically Forced Turbulent Flows</title>
      <link>https://trid.trb.org/View/2427749</link>
      <description><![CDATA[Many turbulent flows exhibit time-periodic statistics. These include turbomachinery flows, flows with external harmonic forcing, and the wakes of bluff bodies. Many existing techniques for identifying turbulent coherent structures, however, assume the statistics are statistically stationary. In this paper, the authors leverage cyclostationary analysis, an extension of the statistically stationary framework to processes with periodically varying statistics, to generalize the spectral proper orthogonal decomposition (SPOD) to the cyclostationary case. The resulting properties of the cyclostationary SPOD (CS-SPOD for short) are explored, a theoretical connection between CS-SPOD and the harmonic resolvent analysis is provided, simplifications for the low and high forcing frequency limits are discussed, and an efficient algorithm to compute CS-SPOD with SPOD-like cost is presented. The authors illustrate the utility of CS-SPOD using two example problems: a modified complex linearized Ginzburg-Landau model and a high-Reynolds-number turbulent jet.]]></description>
      <pubDate>Mon, 23 Sep 2024 09:05:40 GMT</pubDate>
      <guid>https://trid.trb.org/View/2427749</guid>
    </item>
    <item>
      <title>SHALLOW WATER FLOWS PAST SLENDER BODIES</title>
      <link>https://trid.trb.org/View/158160</link>
      <description><![CDATA[The problem solved concerns the disturbance to a stream of shallow water due to an immersed slender body, with special application to the steady motion of ships in shallow water.  Formulae valid to first order in slenderness are given for the wave resistance and vertical forces at both sub- and supercritical speeds.  The vertical forces are used to predict sinkage and trim of ships and satisfactory comparisons with model experiments are made.]]></description>
      <pubDate>Thu, 21 May 1981 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/158160</guid>
    </item>
    <item>
      <title>ON THE MOVEMENTS OF SHIPS IN RESTRICTED WATERWAYS</title>
      <link>https://trid.trb.org/View/158116</link>
      <description><![CDATA[No Abstract.]]></description>
      <pubDate>Thu, 12 Mar 1981 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/158116</guid>
    </item>
    <item>
      <title>ON THE INTERACTIONS OF SLENDER SHIPS IN SHALLOW WATER</title>
      <link>https://trid.trb.org/View/74206</link>
      <description><![CDATA[The unsteady hydrodynamic interaction of two bodies moving in a shallow fluid is examined by applying slender-body theory.  The bodies are assumed to be in each other's far field and the free surface is assumed to be rigid.  By matched asymptotics, the inner and outer problems are formulated and a pair of coupled integro-differential equations for determining the unknown cross flows is derived.  The degree of coupling is shown to be related to a bottom-clearance parameter.  Expressions are given for the unsteady sinkage force, trimming moment, sway force, and yaw moment.  Numerical calculations for two weakly coupled cases are presented.  One corresponds to the interaction of a stationary body with a passing one, the other to the interaction of two bodies moving in a steady configuration. Theoretical results are compared with existing experimental data.]]></description>
      <pubDate>Sat, 19 Aug 1978 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/74206</guid>
    </item>
    <item>
      <title>WAVE FORCES ON VERTICAL BODIES OF REVOLUTION</title>
      <link>https://trid.trb.org/View/74207</link>
      <description><![CDATA[The axisymmetry of a body which is diffracting water waves may be exploited to give a line integral equation to be solved for the scattered wave field and forces on the body. Each term in a previously established surface integral equation is shown to be expressible as a Fourier series, which is then integrated once analytically.  The resulting one-dimensional equation is shown to possess singularities, previously ignored by J.  L.  Black.  This equation, with series transformations and subtraction of singularities such that all series are quickly convergent and that it has to be solved only along a curve, reduces computational effort by some three orders of magnitude.  Results obtained by this method give good agreement with previous analytical and experimental results, even if a rather coarse numerical approximation is used.]]></description>
      <pubDate>Sat, 19 Aug 1978 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/74207</guid>
    </item>
    <item>
      <title>CAVITATION NOISE AND INCEPTION AS INFLUENCED BY BOUNDARY-LAYER DEVELOPMENT ON A HYDROFOIL</title>
      <link>https://trid.trb.org/View/60367</link>
      <description><![CDATA[This paper describes measurements of noise from two-phase flow over hydrofoils.  The experiments were performed in a variable-pressure water tunnel which was acoustically calibrated so that sound power levels could be deduced from the sound measurements.  It is partially reverberant in the frequency range of interest.  Cavitation was generated on a hydrofoil in the presence of either a separated laminar boundary layer or a fully turbulent attached boundary layer. The turbulent boundary layer was formed downstream of a trip which was positioned near the leading edge.  High-speed photographs show the patterns of cavitation which were obtained in each case.  The noise is shown to depend on the type of cavitation produced.]]></description>
      <pubDate>Tue, 27 Dec 1977 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/60367</guid>
    </item>
    <item>
      <title>HEAVE AND PITCH MOTIONS IN SHALLOW WATER INCLUDING THE EFFECT OF FORWARD SPEED</title>
      <link>https://trid.trb.org/View/58840</link>
      <description><![CDATA[The problem of small heave and pitch motions of a slender ship in shallow water including the effect of forward speed is analyzed using the method of matched asymptotic expansions.  Formulae valid to first order in slenderness are given for the added-mass and damping coefficients in terms of the frequency and subcritical Froude number.]]></description>
      <pubDate>Thu, 13 Oct 1977 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/58840</guid>
    </item>
    <item>
      <title>THREE-DIMENSIONAL THEORY ON SUPERCAVITATING HYDROFOILS NEAR A FREE SURFACE</title>
      <link>https://trid.trb.org/View/36898</link>
      <description><![CDATA[Supercavitating hydrofoils of large aspect ratio operating near a free surface are investigated, assuming an inviscid and irrotational flow with the effects of gravity and surface tension neglected.  The flow near the foil, treated as two-dimensional, is solved by a nonlinear free-streamline theory, then a three-dimensional "downwash" correction is made using Prandtl's lifting-line theory. The strength of the lifting-line vortex is determined by information from the two-dimensional solution through a matching procedure, in which the inverse of aspect ratio is used as a small parameter for asymptotic expansions.  The analysis incorporates a free-surface reference level to determine the submergence depth of the foil.]]></description>
      <pubDate>Wed, 07 Apr 1976 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/36898</guid>
    </item>
    <item>
      <title>THREE-DIMENSIONAL LAW OF THE WALL FOR TURBULENT SHEAR FLOWS</title>
      <link>https://trid.trb.org/View/35701</link>
      <description><![CDATA[An extended law of the wall is derived for three-dimensional flows.  It describes the variation of the magnitude and direction of velocity close to the wall.  The effects of both the pressure gradient and the inertial forces have been taken into account.  The derived wall law is valid only when the deviations from the simple law of the wall are not large.  The most important feature of a three-dimensional wall law is the prediction of the rotation of the velocity vector near the wall.  Comparison of the flow angle variations predicted by the present wall law with the few available experimental data shows good agreement.]]></description>
      <pubDate>Wed, 14 Jan 1976 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/35701</guid>
    </item>
    <item>
      <title>DIFFRACTION OF OBLIQUE WAVES BY AN INFINITE CYLINDER</title>
      <link>https://trid.trb.org/View/34966</link>
      <description><![CDATA[This paper presents a numerical method for solving linearized water-wave problems with oscillatory time dependence.  Specifically it considers the diffraction problem for oblique plane waves incident upon an infinitely long fixed cylinder on the free surface.  The numerical method is based on a variational principle ezuivalent to the linearized boundary-value problem.  Finite-element techniques are used to represent the velocity potential; and the variational principle is used to determine the unknown coefficients in the solution throughout the fluid domain. To illustrate this method, reflection and transmission coefficients and the diffraction forces and moment are computed for oblique waves incident upon a vertical flat plate, a horizontal flat plate and rectangular cylinders, where the comparison is made with the existing results by others.]]></description>
      <pubDate>Wed, 05 Nov 1975 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/34966</guid>
    </item>
    <item>
      <title>ON THE PREDICTION OF INTERMITTENT TURBULENT FLOWS</title>
      <link>https://trid.trb.org/View/40341</link>
      <description><![CDATA[A theoretical model is presented which permits the conservation equations of fluid dynamics to be conditioned in a fashion analogous to the experimentalist's technique of "conditioned sampling".  The detailed analysis refers to the best-known sampling condition, outer-edge intermittency; but the model equation may be applicable to other flow situations, wherein conditioning exposes details of the physical phenomena.  The analysis results in predictions of the flow variables within the turbulent flow and of the intermittency.  Comparison is made with two sets of experimental results for the two-dimensional mixing layer and with a boundary layer.]]></description>
      <pubDate>Tue, 30 Sep 1975 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/40341</guid>
    </item>
    <item>
      <title>ON THE INCIPIENT BREAKING OF SMALL SCALE WAVES</title>
      <link>https://trid.trb.org/View/26775</link>
      <description><![CDATA[It is shown that the surface wind drift in the ocean substantially reduces the maximum wave height and wave orbital velocity that can be attained before breaking. Incipient breaking in a steady wave train is characterized by the occurrence of stagnation points at wave crests, but not necessarily by discontinuities in slope.  After breaking, there is in the mean flow a stagnation point relative to the wave profile near the crest of the broken wave, on one side of which the water tumbles forward and behind which recedes more smoothly to the rear.  Some simple flow visualization studies indicate the general extent of the wake behind the breaking region.]]></description>
      <pubDate>Mon, 19 May 1975 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/26775</guid>
    </item>
    <item>
      <title>MEASUREMENT OF TURBULENCE INTENSITIES USING REAL-TIME LASER-DOPPLER VELOCIMETRY</title>
      <link>https://trid.trb.org/View/26938</link>
      <description><![CDATA[A technique by which the effect of the random phase fluctuations or Doppler ambiguity can be removed from measurements of turbulence intensities by the laser-Doppler velocimeter is proposed.  Because the ambiguity is often much broader band than the turbulence, it is proposed that a sequence of low-pass filters at frequencies above those of the turbulence be used in the measurement of turbulence intensities.  The true turbulence intensity is given by the extrapolation of these measurements to zero frequency.]]></description>
      <pubDate>Mon, 19 May 1975 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/26938</guid>
    </item>
    <item>
      <title>SOME TURBULENT/NON-TURBULENT PROPERTIES OF THE OUTER INTERMITTENT REGION OF A BOUNDARY LAYER</title>
      <link>https://trid.trb.org/View/24862</link>
      <description><![CDATA[A detailed study of the intermittency in the outer region of a flat-plate turbulent boundary layer has been carried out using digital sampling and processing techniques. Conditional averages are used to generate mean and fluctuating components for the turbulent and non-turbulent zones of fluid.  More particularly, point averages of these variables, taken with reference to the instantaneous position of the turbulent/non-turbulent interface, have been made to show the distribution of various quantities through the turbulent front.  The results indicate that significant differences exist at leading and trailing edges of the turbulent bursts and a more complete picture of the motion of an average large eddy is deduced.]]></description>
      <pubDate>Tue, 31 Dec 1974 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/24862</guid>
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