Ermittlung der Kriechfunktionen von zweiachsig beanspruchten Harzen und Laminaten aus den Meßwerten für einachsig beanspruchte Harze / Calculation of the creep function for two dimensional loaded resins and GF-UP from the experimental values for uniaxial loaded resins / Calcul de fonction au fluage pour résineux et laminées charger bidimensional dans valeurs experimentales des résineux charger uniaxial

1981 ◽  
Vol 23 (3) ◽  
pp. 75-85
Author(s):  
E. Giencke ◽  
G. Meder
Keyword(s):  
Creep Function ◽  
Two Dimensional ◽  
Experimental Values

Measurements of Apparent Mass Torque Coefficients of Two-Dimensional Centrifugal Impellers

1986 ◽  
Vol 108 (4) ◽  
pp. 407-413
Author(s):  
Y. Tsujimoto ◽  
K. Imaichi ◽  
T. Moritani ◽  
K. Kim
Keyword(s):  
Angular Velocity ◽  
Flow Rate ◽  
Potential Flow ◽  
Rotational Velocity ◽  
Apparent Mass ◽  
Two Dimensional ◽  
Drag Torque ◽  
Mean Flow ◽  
Experimental Values

Apparent mass torque coefficients for fluctuations of flow rate and angular velocity are determined experimentally for two-dimensional centrifugal impellers. Nearly sinusoidal fluctuations of flow rate and angular velocity are produced by using crank mechanisms, and the resulting unsteady torque on the impeller is measured. The torque is divided into components in-phase and out-of-phase with the displacements. The in-phase components are used to determine the apparent mass coefficients. Drag torque coefficients are defined and used to represent the out-of-phase components. The tests are conducted under various frequencies and amplitudes of the fluctuations with zero mean flow rate and rotational velocity. The apparent mass torque coefficients are compared with theoretical values obtained under the assumption of a two-dimensional potential flow. The experimental values are 5 to 20 percent larger than the theoretical ones and no appreciable effects of the frequency and the amplitude are observed within the range of the experiments.

Theoretical Analysis of Flow Through Two-Dimensional Centrifugal Pump Impeller by Method of Singularities

1971 ◽  
Vol 93 (1) ◽  
pp. 35-40 ◽  
Author(s):  
S. K. Ayyubi ◽  
Y. V. N. Rao
Keyword(s):  
Centrifugal Pump ◽  
Operating Conditions ◽  
Two Dimensional ◽  
Pump Impeller ◽  
Pump Operation ◽  
Wide Range ◽  
Hydrodynamic Method ◽  
Flow Through ◽  
Experimental Values ◽  
Centrifugal Pump Impeller

The hydrodynamic method of singularities is used to analyze the flow through two-dimensional centrifugal pump impellers with blades of an arbitrary geometry. Computed values of ideal head are compared with experimental values obtained for a commercial pump. The agreement between theory and experiment is very close over a wide range of pump operation. The discrepancies that occur at other operating conditions are attributed to the effects of inlet passage and volute casing.

An Approximate Method for the Drags of Two-Dimensional Obstacles at Low Reynolds Numbers

1996 ◽  
Vol 63 (4) ◽  
pp. 990-996 ◽  
Author(s):  
Hideo Yano ◽  
Katsuya Hirata ◽  
Masanori Komori
Keyword(s):  
Reynolds Numbers ◽  
Circular Cylinders ◽  
Two Dimensional ◽  
Governing Equations ◽  
Simple Method ◽  
Drag Coefficients ◽  
Low Reynolds Numbers ◽  
Singularity Method ◽  
Experimental Values ◽  
Discrete Singularity Method

We propose a new simple method of computing the drag coefficients of two-dimensional obstacles symmetrical to the main-flow axis at Reynolds numbers less than 100. The governing equations employed in this method are the modified Oseen’s linearized equation of motion and continuity equation, and the computation is based on a discrete singularity method. As examples, simple obstacles such as circular cylinders, rectangular prisms, and symmetrical Zhukovskii aerofoils are considered. And it was confirmed that the computed drags agree well with experimental values. Besides optimum shapes of these geometries, which minimize the drag coefficients, are also determined at each Reynolds number.

NUMERICAL PREDICTION OF SLAMMING LOADS DURING WATER ENTRY OF BOW-FLARED SECTIONS

2021 ◽  
Vol 156 (A4) ◽  
Author(s):  
Shan Wang ◽  
H B Luo ◽  
C Guedes Soares
Keyword(s):  
Mesh Size ◽  
Water Entry ◽  
Two Dimensional ◽  
Arbitrary Lagrangian Eulerian ◽  
Pressure Distributions ◽  
Good Consistency ◽  
Convergence Study ◽  
Experimental Values ◽  
Coupling Algorithm ◽  
Force Pressure

The two-dimensional water entry of bow-flared sections is studied by using a Multi-Material Arbitrary Lagrangian- Eulerian (MMALE) formulation and a penalty-coupling algorithm. A convergence study is carried out, considering the effects of mesh size, the dimension of fluids domain, and fluid leakage phenomenon through the structure. The predicted results on the wetted surface of a bow-flared section are compared with published experimental values in terms of vertical slamming force, pressure distributions at different time instances and the pressure histories at different points. Comparisons between the numerical results and measured values show satisfactory correlation. An approximation method is adopted to estimate the sectional slamming force showing good consistency for the peak forces.

Predicting the long-term performance of a geogrid-reinforced embankment on soft soil using two-dimensional finite element analysis

2011 ◽  
Vol 48 (5) ◽  
pp. 741-753 ◽  
Author(s):  
M.R. Karim ◽  
G. Manivannan ◽  
C.T. Gnanendran ◽  
S-C.R. Lo
Keyword(s):  
Finite Element ◽  
Lateral Displacement ◽  
Water Pressure ◽  
Soft Soil ◽  
Creep Function ◽  
Nonlinear Creep ◽  
Two Dimensional ◽  
Foundation Soil ◽  
Prefabricated Vertical Drains

The consolidation of the soft foundation soil of a geogrid-reinforced embankment, improved with prefabricated vertical drains (PVDs), is modelled in this paper using two-dimensional (2D) plane strain coupled finite element (FE) analysis to predict long-term multiple behaviour characteristics (e.g., settlement, lateral displacement, excess pore-water pressure response, geosynthetic strain) of the embankment. Two sets of analyses were carried out with the foundation soil being modelled using relatively simple elastic–viscoplastic (EVP) models. A nonlinear creep function was used in association with them. The input material parameters were determined from extensive laboratory testing or were taken from reliable sources except for the horizontal permeability, which was systematically back-estimated using oedometer test data and the first year of field settlement data. The results from both analyses were compared with the long-term (up to 6 years) field-monitoring data and were found to be in good agreement with the field measurements.

Part 4 — Two dimensional dynamic stall

1987 ◽  
Vol 91 (902) ◽  
pp. 72-88 ◽  
Author(s):  
G. J. Hancock ◽  
J. S. Y. Lam
Keyword(s):  
Limit Cycle ◽  
Dynamic Responses ◽  
Dynamic Stall ◽  
Two Dimensional ◽  
Linear Set ◽  
Impulsive Input ◽  
Aerodynamic Model ◽  
Aerodynamic Derivatives ◽  
Experimental Values ◽  
General Motion

Summary An axiomatic aerodynamic model has been developed for the general motion of a two dimensional aerofoil as it passes in and out of stall, which gives realistic unsteady loads as compared to experimental values. A non-linear set of aerodynamic derivatives with time delays have been derived from the axiomatic aerodynamics. ‘Actual’ and ‘predicted’ dynamic responses of an aerofoil, spring restrained in torsion, following an impulsive input show similar trends, including limit cycle oscillations, although there is a slight difference in frequency and a difference in the magnitude of the initial impulse required to trigger the limit cycle.

Evaluation of the Theory for the Flow Pattern of a Hydrofoil of Finite Span

1960 ◽  
Vol 4 (01) ◽  
pp. 13-29
Author(s):  
Paul Kaplan ◽  
John P. Breslin ◽  
Winnifred R. Jacobs
Keyword(s):  
Surface Wave ◽  
Flow Field ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Limited Data ◽  
Flow Properties ◽  
Dimensional Theory ◽  
Finite Span ◽  
Wave Elevation ◽  
Experimental Values

Expressions for various properties of the flow field aft of a finite-span hydrofoil in smooth water are presented and discussed in this paper. Potential functions for the motion that have been derived previously on the basis of linearized free-surface theory serve as the basic terms from which the flow field is derived. Both two-dimensional and three-dimensional theories are used, and the expressions derived for the surface-wave elevation and downwash from the various theories are compared with experimental values. As a result of this study, it is shown that three-dimensional effects are of great importance and hence terms derived from the two-dimensional theory do not accurately represent the true flow properties. Recommended formulas, whose validity is demonstrated by the comparison with the limited data presented herein, are given for the evaluation of both the surface-wave amplitude and downwash.

Vibrational Dynamics of the H2O . HF Complex. Potential Energy and Electric Dipole Moment Surfaces

1993 ◽  
Vol 58 (12) ◽  
pp. 2813-2830 ◽  
Author(s):  
Andrzej J. Sadlej ◽  
Ota Bludský ◽  
Vladimír Špirko
Keyword(s):  
Dipole Moment ◽  
Potential Energy ◽  
Electric Dipole Moment ◽  
Electric Dipole ◽  
Vibrational Energy ◽  
Dipole Moments ◽  
Energy Levels ◽  
Equilibrium Geometry ◽  
Two Dimensional ◽  
Experimental Values

A total of 330 points on the potential energy and electric dipole moment surfaces of the ground electronic state of the H2O . HF complex have been calculated ab initio using the SCF method and many-body perturbation theory (MBPT). To keep the calculations manageable, the geometry parameters of H2O were fixed at their experimental values and only certain two dimensional sections of the total surfaces have been evaluated. for each of the two-dimensional surface section, analytic potential energy and electric dipole moment functions have been fitted through the points and corresponding vibrational energy levels and effective electric dipole moments have been calculated using approximate vibrational Hamiltonians. The calculated values of resulting vibrational energies and effective electric dipoles from differently wide intervals for different vibrational modes. The intervals corresponding to the most interesting low frequency modes (out-of-plane and H2O vs HF stretching) are very narrow and coincide satisfactory with the corresponding experimental values. A very reasonable agreement has also been obtained for the equilibrium geometry, electric dipole moment and dissociation energy De of the complex. These findings lead us to believe that the calculated potential energy and electric dipole moment surfaces are sufficiently accurate for predicting purposes and rationalization of the so far unassigned spectral data of H2O . HF.

Numerical Simulation of Two-Part Underwater Towing System: A Lumped Mass-Spring System Approach

2007 ◽  
Author(s):  
P. P. Lalu
Keyword(s):  
System Approach ◽  
Two Dimensional ◽  
Lumped Mass ◽  
System A ◽  
Submerged Body ◽  
Induced Motion ◽  
Spring System ◽  
Experimental Values ◽  
Mass Spring ◽  
Wave Induced

The altitude and position of a submerged body being towed by a vessel is affected by wave induced motion of the latter. To reduce this disturbance, a two-part towing system is used. In this study a two-dimensional dynamic model of the two-part underwater towing system is described. Numerical modeling of the problem was attempted. The finite difference algorithm was used to formulate the problem. A lumped mass-spring system was used for modeling the cable. The formulation for the towed body was based on Kirchhoff’s equations for motion of a rigid body. For the demonstration of the model, a numerical example of the tow-ship traveling in a wave field is described. Subsequently, response of the towed body was simulated and is compared with the experimental values obtained from the literature.

Two-dimensional planar plumes and fountains

2014 ◽  
Vol 750 ◽  
pp. 210-244 ◽  
Author(s):  
T. S. van den Bremer ◽  
G. R. Hunt
Keyword(s):  
Uniform Density ◽  
Two Dimensional ◽  
Closed Form Solutions ◽  
Entrainment Velocity ◽  
Entrainment Coefficient ◽  
Flow Features ◽  
Gravity Driven ◽  
Planar Area ◽  
Experimental Values ◽  
Universal Solutions

AbstractClosed-form solutions describing the behaviour of two-dimensional planar turbulent rising plumes and fountains from horizontal planar area and line sources in unconfined quiescent environments of uniform density are proposed. Extending the analysis on axisymmetric releases by van den Bremer & Hunt (J. Fluid Mech., vol. 644, 2010, pp. 165–192) to planar releases, the local flux balance parameter $\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf {#1}}}\let \le =\leqslant \let \leq =\leqslant \let \ge =\geqslant \let \geq =\geqslant \def \Pr {\mathit {Pr}}\def \Fr {\mathit {Fr}}\def \Rey {\mathit {Re}}\varGamma =\varGamma (z)$ is instrumental in describing the bulk behaviour of steady Boussinesq and non-Boussinesq planar plumes and the initial rise behaviour of Boussinesq planar fountains as a function of height $z$. Expressions for the asymptotic virtual source correction are developed and the results elucidated by ‘scale diagrams’ (cf. Morton & Middleton, J. Fluid Mech., vol. 58, 1973, pp. 165–176) showing certain characteristic heights for different source conditions. These diagrams capture all the different manifestations of plume behaviour, encompassing fountains, jets, source-momentum-dominated or ‘forced’ plumes, pure plumes and source-buoyancy-dominated or ‘lazy’ plumes, and their associated key features. Other flow features identified include a gravity-driven deceleration regime and a mixing-driven regime for forced fountains. Deceleration in lazy fountains is purely gravity-driven. The results can be shown to be valid for both Boussinesq and non-Boussinesq plumes (but not for non-Boussinesq fountains) thus resulting in universal solutions valid for both cases provided the entrainment velocity is unaffected by non-Boussinesq effects. This paper presents and explores these universal solutions. An accompanying paper (van den Bremer & Hunt, J. Fluid Mech., vol. 750, 2014, pp. 245–258) examines the implications for non-Boussinesq plumes. The existing solutions of Lee & Emmons (J. Fluid Mech., vol. 11, 1961, pp. 353–368) generalized herein are valid for a constant entrainment coefficient $\alpha $. New results for an entrainment coefficient that varies linearly with $\varGamma (z)$ and thus captures experimental values far more realistically are presented for forced plumes.

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