Abstracts - KTH Mechanics

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194 U i /U c 6 5 4 3 2 1 0 linear fit DNS 5 10 z/De 15 20 z/D e 2 1.8 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0 -0.2 -1 -0.5 0 0.5 1 r/De 0.1 0 0.3 0.5 0.7 0.9 0 0.7 0.5 0.3 -0.1 0.7 0.9 0.5 0.3 0.1 0
Turbulent mixing in the entry region of confined coaxial jets P. M. Areal ∗ and J.M.L.M. Palma ∗ Coaxial jets is a flow configuration common in many engineering devices (aircraft reactors, combustion chambers, etc.) where mixing is important. In case the velocity ratio is different from 1, these flows usually exhibit large turbulent structures and can be most appropriate to be dealt by the Large-Eddy Simulation (LES) approach to turbulence modelling. In this work, previous experiments 1 , using simultaneously LDV for the velocity field and LIF (laser induced fluorescence) for the passive scalar, were re-analysed and insight on the turbulent mixing was sought using LES. The flow geometry comprised 2 coaxial water flows, with a diameter ratio of 2.5 (42/17 mm). The Reynolds numbers, based on bulk velocity, are 29400 for case 1 and 35000 for case 2, with annular to central bulk velocity ratio equal to 0.8 (0.83/1.08 ms −1 ) and 3.5 (0.83/0.26 ms −1 ). A fractional-step, 2nd order, LES code 2 was adapted to the cylindrical geometry with a non-orthogonal grid. To account for the effects of the filtered small scales on the large resolved ones, a Lagrangian dynamic subgrid model 3 was used for the velocity field and extended to the scalar field assuming a uniform turbulent Schmidt number of 1. The results showed the ability of the LES to capture the main features of the flow. Deficiencies of the current set of results (figure) are expected to be removed by reverting to a fully dynamic model for the scalar subgrid terms 4 (whose implementation is currently underway), with a spatially variable turbulent Schmidt number, and alternative treatments of the inlet conditions. ∗ Faculdade de Engenharia da Universidade do Porto, Research Centre for Wind Energy and Atmospheric Flows, Rua Dr. Roberto Frias s/n, 4200-465 Porto, Portugal. 1 Lima, M. and Palma, J.M.L.M., http://in3.dem3.dem.ist.utl.pt/lxlaser2002/papers.asp, (2002). 2 Silva Lopes A. and Palma J.M.L.M., Journal of Computational Physics, 175,713 (2002). 3 Armenio V. and Piomelli U., Flow, Turbulence and Combustion 65, 51 (2000). 4 Keating A. et al J. of Turbulence, 5, 20 (2004). r/R i 2 1.5 1 0.5 0 0 0.25 0.5 0.75 1 U/Ucl 0 0.25 0.5 C/Ccl 0.75 1 0 0.1 u/Ucl 0.2 Figure 1: Mean longitudinal velocity (U), mean concentration (C) and fluctuating longitudinal velocity ( √ uu), made dimensionless by the mean centerline values. 195
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EFMC6 KTH Electronic version Abstra
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Euromech Fluid Mechanics Lecturer H
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ii Continuum Models in Industrial A
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iv Slip Behavior at Liquid/Solid In
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vi ¡ £ ¥ § © £ § £
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viii Premixed Turbulent combustion
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Session 1
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2 Global stability of jets and sens
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4 Control of instabilities in a cav
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6 The dispersal, decay and instabil
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8 Steady and pulsatile flow through
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10 Pulsatile flows in pipes with fi
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Global stability of the rotating di
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Continuous Spectrum Growth and Moda
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The influence of centrifugal buoyan
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Prediction of wall bounded flows us
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Uncertainty Quantification in Large
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Stratified turbulence G. Brethouwer
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Investigations of turbulence statis
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Coupling weather-scale flow with st
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Flow Separation from a Free Surface
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Phase-Field Simulations of Free Bou
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Evaluation of a universal transitio
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Computations of turbulent boundary
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Flow Developments in Smooth Wall Ci
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Super-late stages of boundary-layer
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Low-speed streaks developing at the
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Direct Numerical Simulation of Lami
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44 Axisymmetric absolute instabilit
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46
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Application of the ray-tracing theo
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Leaky Waves in Supersonic Boundary
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Solving turbulent wall flow in 2D u
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55 Development of a 3D transient in
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58 Upper bounds for the long-time a
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60 Numerical Simulations of Rigid F
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62 On the translational and rotatio
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64 A Shell-Model Study of Turbulent
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66 Using CSP for Modeling Burgers-T
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68 High Spatially Resolved Velocity
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Dynamic Lift of Airfoils R. Grüneb
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72 Experimental study on the bounda
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74 Natural sinuous and varicose bre
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Numerical simulation of the three-d
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Effects of the flexibility of the a
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Wave forerunners of longitudinal st
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Stability and sensitivity analysis
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Stability of reacting gas jets Jose
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Elastocapillarity in wet hairs J. B
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Open Capillary Channel Flows (CCF):
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Stick-slip motion of droplets of co
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94 A general theory for stratified
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96 £ ¥ § © £ ¥ ©
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98 The influence of the density max
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100 TRANSIENT DISPLACEMENT OF A NEW
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102 Experimental study of the effec
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104 Nu Numerical modeling of heat t
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106 Turbulent thermal convection ov
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110 Modelling of optimal vortex rin
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112 The effect of a sphere on a swi
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114 Three-dimensional stability of
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Session 4
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Nonlinear long waves on an interfac
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Three-dimensional gravity-capillary
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Linear and non-linear theory of lon
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Surface oscillations of liquid nitr
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Waves above turbulence R. Savelsber
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Figure 1 : Vorticity contours and s
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Investigation of flow structure upo
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Simultaneous density and concentrat
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Introduction of newly developed tow
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136 A Simple Model for Gas-Grain Tw
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138 Dynamics of heavy particles nea
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140 Stability of dusty gas flow in
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142 Joint fluid-particle pdf modeli
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144 Three-dimensional stability of
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Page 178 and 179: 152 Direct numerical simulations of
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Page 232 and 233: LIST OF AUTHORS Borel H. 340 Castro
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Page 238 and 239: LIST OF AUTHORS Poplavskaya T. V. 4
Page 240: LIST OF AUTHORS Tuzi R. 11 Wolters
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Abstracts - KTH Mechanics

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