scholarly journals The three-dimensional interaction of a vortex pair with a wall

1997 ◽  
Vol 9 (10) ◽  
pp. 2967-2980 ◽  
Author(s):  
J. Alan Luton ◽  
Saad A. Ragab
Keyword(s):  
Three Dimensional ◽  
Vortex Pair ◽  
Dimensional Interaction

Three-Dimensional Interaction Effects in an Internally Multicracked Pressurized Thick-Walled Cylinder— Part I: Radial Crack Arrays

1996 ◽  
Vol 118 (3) ◽  
pp. 357-363 ◽  
Author(s):  
M. Perl ◽  
C. Levy ◽  
J. Pierola
Keyword(s):  
Radial Crack ◽  
Crack Depth ◽  
Three Dimensional ◽  
Internal Surface ◽  
Interaction Effects ◽  
Life Assessment ◽  
Fatigue Life Assessment ◽  
Dimensional Interaction ◽  
Least Squares Fit ◽  
Wide Range

Under certain conditions, numerous internal surface cracks develop in pressurized thick-walled cylinders, both in the radial and longitudinal directions. For fatigue life assessment of such vessels, the 3-D interaction effects among these cracks on the prevailing stress intensity factors (SIFs) need evaluation. In Part I of this paper, radial crack arrays are considered exclusively. The mode I SIF distribution for a wide range of semi-circular and semi-elliptical cracks are evaluated. The 3-D analysis is performed via the finite element method with the submodeling technique, employing singular elements along the crack front. SIFs are evaluated for arrays of up to n = 180 cracks; for a wide range of crack depth to wall thickness ratios, a/t, from 0.05 to 0.6; and, for various ellipticities of the crack, i.e., the ratio of crack depth to semicrack length, a/c, from 0.2 to 2. Using a least-squares fit, two simple expressions for the most critical (n = 2) SIFs are obtained for sparse and dense crack arrays. The formulas, which are functions of a/t and a/c, are of very good engineering accuracy. The results clearly indicate that the SIFs are considerably affected by the interaction among the cracks in the array as well as the three-dimensionality of the problem. In Part II of this paper, the interaction effects between longitudinal coplanar cracks will be analyzed.

scholarly journals On the formation of the counter-rotating vortex pair in transverse jets

2001 ◽  
Vol 446 ◽  
pp. 347-373 ◽  
Author(s):  
L. CORTELEZZI ◽  
A. R. KARAGOZIAN
Keyword(s):  
Flow Field ◽  
Computational Study ◽  
Near Field ◽  
Three Dimensional ◽  
Vortex Pair ◽  
Transverse Jets ◽  
Vortical Structures ◽  
Jet In Crossflow ◽  
Dynamical Generation ◽  
Counter Rotating Vortex Pair

Among the important physical phenomena associated with the jet in crossflow is the formation and evolution of vortical structures in the flow field, in particular the counter-rotating vortex pair (CVP) associated with the jet cross-section. The present computational study focuses on the mechanisms for the dynamical generation and evolution of these vortical structures. Transient numerical simulations of the flow field are performed using three-dimensional vortex elements. Vortex ring rollup, interactions, tilting, and folding are observed in the near field, consistent with the ideas described in the experimental work of Kelso, Lim & Perry (1996), for example. The time-averaged effect of these jet shear layer vortices, even over a single period of their evolution, is seen to result in initiation of the CVP. Further insight into the topology of the flow field, the formation of wake vortices, the entrainment of crossflow, and the effect of upstream boundary layer thickness is also provided in this study.

scholarly journals Comparative analysis of calculations of strip foundation, taking into account the influence of adjoined building with different soil models

2019 ◽  
Vol 97 ◽  
pp. 04006
Author(s):  
Nataliia Lobacheva ◽  
Vadim Griniov
Keyword(s):  
Three Dimensional ◽  
Natural Occurrence ◽  
Strip Foundation ◽  
Soil Base ◽  
Existing Building ◽  
Dimensional Interaction ◽  
Coulomb Model ◽  
The Difference ◽  
Hardening Soil Model ◽  
Properties Of Soil

The necessity to take into account the properties of soil foundations, which depend not only on the conditions of their natural occurrence, but also on the stress state, led researchers to create a large number of different soil models. This article provides is to clarify the patterns and features of the three-dimensional interaction of strip foundations with the soil base in conditions of dense urban development with the use of various design soil models and comparison with field observations. Three soil models (the Mohr-Coulomb model, the Hardening-Soil model, model of the Klepikov stiffness coefficient) are considered. The calculation stages displayed a true picture of the construction of a new building (dismantling of the floor of an existing building, excavation, etc.). As a result of numerical experiments with a use of Plaxis and methods for calculating structures on a deformable base was received values settlement of strip foundations in applying three soil models. The difference of the calculated values of strip foundation settlement is defined in percentage. The geodesic monitoring confirms the validity of the research.

The Three-Dimensional Interaction of a Shock Wave with a Turbulent Boundary Layer

1966 ◽  
Vol 17 (3) ◽  
pp. 231-252 ◽  
Author(s):  
A. McCabe
Keyword(s):  
Boundary Layer ◽  
Shock Wave ◽  
Turbulent Boundary Layer ◽  
Reasonable Agreement ◽  
Three Dimensional ◽  
Side Wall ◽  
Approximate Theory ◽  
Streamwise Vorticity ◽  
Supersonic Wind Tunnel ◽  
Dimensional Interaction

SummaryExperiments are described on the interaction of the shock wave generated by a wedge in a supersonic wind tunnel with the turbulent boundary layer on the side wall. It is shown that the onset of separation appears to be largely affected by the action of streamwise vorticity in the interaction region. A simple approximate theory based on this concept shows reasonable agreement with the experimental results. Comparisons have been made with two-dimensional interactions of normal shocks and boundary layers, but they did not produce any conclusive results.

INFLOW/OUTFLOW CONDITIONS FOR TIME-HARMONIC INTERNAL FLOWS

2002 ◽  
Vol 10 (02) ◽  
pp. 155-182 ◽  
Author(s):  
OLIVER V. ATASSI ◽  
AMR A. ALI
Keyword(s):  
Acoustic Waves ◽  
Numerical Scheme ◽  
Truncation Error ◽  
Numerical Solutions ◽  
Three Dimensional ◽  
Internal Flows ◽  
Vortex Sheets ◽  
Dimensional Interaction ◽  
Time Harmonic ◽  
Annular Cascade

Inflow/Outflow conditions are formulated for time-harmonic waves in a duct governed by the Euler equations. These conditions are used to compute the propagation of acoustic and vortical disturbances and the scattering of vortical waves into acoustic waves by an annular cascade. The outflow condition is expressed in terms of the pressure, thus avoiding the velocity discontinuity across any vortex sheets. The numerical solutions are compared with the analytical solutions for acoustic and vortical wave propagation with and without the presence of vortex sheets. Grid resolution studies are also carried out to discern the truncation error of the numerical scheme from the error associated with numerical reflections at the boundary. It is observed that even with the use of exponentially accurate boundary conditions, the dispersive characteristics of the numerical scheme may result in small reflections from the boundary that slow convergence. Finally, the three-dimensional interaction of a wake with a flat plate cascade is computed and the aerodynamic and aeroacoustic results are compared with those of lifting surface methods.

Formation of a Counter-Rotating Vortex Pair in a Plume in a Cross-Flow

2010 ◽  
Author(s):  
Masahiko Shinohara
Keyword(s):  
Vortex Ring ◽  
Three Dimensional ◽  
Cross Flow ◽  
Vortex Pair ◽  
Boussinesq Approximation ◽  
Streamwise Vorticity ◽  
Three Dimensional Flow ◽  
Flow Feature ◽  
Heated Area ◽  
Counter Rotating Vortex Pair

Numerical simulations are performed to study the formation of a counter-rotating vortex pair (CVP), a dominant flow feature in plumes inclined in a cross-flow. The unsteady three-dimensional flow fields are calculated by a finite difference method using the Boussinesq approximation. A plume rises from an isothermally heated square surface facing upward in air. Calculations show that the CVP originates not from horizontal spanwise vorticity in the velocity boundary layer on the bottom wall around the heated area, but from horizontal streamwise vorticity just above each side of the heated area. When the cross-flow begins after a plume forms a vortex ring in the cap above the heated area in a still environment, the vortex ring does not form a CVP. However, as the cap and the stem of the plume move downwind, a rotation about the streamwise axis appears just above each side edge of the heated area and grows into the CVP. We discuss the effect of entrainment into the stem and cap on the formation of the streamwise rotation that causes the CVP.

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