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  • Books  (2)
  • Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
  • MDPI - Multidisciplinary Digital Publishing Institute
  • 1990-1994  (2)
  • 1
    Series available for loan
    Series available for loan
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Associated volumes
    Call number: ZSP-201-94/5
    In: CRREL Report, 94-5
    Description / Table of Contents: A three-dimensional theory is derived to describe the temporal behavior of gravity currents of cohesionless granular media, in an attempt to model the motion of dense, flow-type snow avalanches, ice and rock slides. A mohr-Coulomb yield criterion is assumed to describe the constitutive behavior of the material, and the basal bed friction is described similarly by a Coulomb type of friction. A drag term is included in order to model the occurrence of flow regimes where boundary drag becomes non-negligible. Data from laboratory simulations are compared to a series of numerical studies based on the aforementioned theory. A nondimensional, depth and width averaged form of the theory is considered. A Lagrangian finite difference scheme is then applied to numerically model some limiting cases of the governing equations. Two different numerical models are developed, tested and compared to experimental values. The results indicate that the model can account for flow transitions by inclusion of the drag term when the initial inclination angle is large enough to affect boundary drag. Furthermore, the temporal and spatial evolution of the granulate and final runout position can be predicted to values well within the experimental error.
    Type of Medium: Series available for loan
    Pages: iv, 29 Seiten , Illustrationen
    Series Statement: CRREL Report 94-5
    Language: English
    Note: CONTENTS Preface Nomenclature Introduction Mathematical formulation Limiting cases of the governing equations Nondimensionalization scheme Numerical solutions and comparison to experiments Unconstrained Coulomb flow model with constant bed friction Unconstrained Coulomb flow with boundary drag term Conclusions and remarks Literature cited Abstract
    Location: AWI Archive
    Branch Library: AWI Library
    Location Call Number Expected Availability
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  • 2
    Series available for loan
    Series available for loan
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Associated volumes
    Call number: ZSP-201-91/12
    In: CRREL Report, 91-12
    Description / Table of Contents: Field trials using a man-portable Geonics, Ltd., EM31 electromagnetic induction sounding instrument, with a plug-in data processing module, for the remote measurement of sea ice thickness, are discussed. The processing module was made by Flow Research Inc., to directly measure sea ice thickness and show the result in a numerical display. The EM31-processing module system was capable of estimating ice thickness within 10% of the true value for ice from about 0.7 to 3.5 m thick, the oldest undeformed ice in the study area. However, since seawater under the Arctic pack ice has a relatively uniform conductivity (2.5 + or - 0.05 S/m), a simplified method, which can be used for estimating sea ice thickness using jet an EM31 instrument, is discussed. It uses only the EM31's conductivity measurement, is easy to put into use and does not rely on theoretically derived look-up tables or phasor diagrams, which may not be accurate for the conditions of the area.
    Type of Medium: Series available for loan
    Pages: iv, 23 Seiten , Illustrationen
    Series Statement: CRREL Report 91-12
    Language: English
    Note: CONTENTS Preface Introduction EM 31 Sounding concepts Previous EMI studies Beaufort Sea field trials EM 31 Conductivity reading versus sea ice thickness General comments Literature cited Abstract
    Location: AWI Archive
    Branch Library: AWI Library
    Location Call Number Expected Availability
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