Transport of ellipsoidal microplastic particles in a 3D lid-driven cavity under size and aspect ratio variation

2022 ◽  
Vol 413 ◽  
pp. 126646
Author(s):  
Nityananda Roy ◽  
Karunia Putra Wijaya ◽  
Thomas Götz ◽  
S. Sundar
Keyword(s):  
Aspect Ratio ◽  
Driven Cavity ◽  
Ratio Variation

Convection in a lid-driven cavity subject to a gravitational stable condition: effects of aspect ratio

2017 ◽  
Author(s):  
Igor Minami Suyama ◽  
Vinicius Gustavo Poletto ◽  
Fernando Cesar De Lai ◽  
Silvio L. M. Junqueira
Keyword(s):  
Aspect Ratio ◽  
Stable Condition ◽  
Driven Cavity

Constructal Design of Rectangular Fin Intruded Into Mixed Convective Lid-Driven Cavity Flows

2016 ◽  
Vol 138 (10) ◽  
Author(s):  
G. Lorenzini ◽  
B. S. Machado ◽  
L. A. Isoldi ◽  
E. D. dos Santos ◽  
L. A. O. Rocha
Keyword(s):  
Nusselt Number ◽  
Aspect Ratio ◽  
Convective Flow ◽  
Numerical Study ◽  
Reynolds Numbers ◽  
Lower Surface ◽  
Driven Cavity ◽  
Constructal Design ◽  
Mixed Convective Flow ◽  
Forced Convective Flow

The present work shows a numerical study of laminar, steady, and mixed convective flow inside lid-driven square cavity with intruded rectangular fin in its lower surface. The main purpose here is to maximize the heat transfer between the rectangular fin and the surrounding mixed convective flow inside a lid-driven cavity by means of constructal design. The problem is subject to two constraints, the lid-driven cavity and intruded fin areas. The ratio between the fin and cavity areas is kept fixed (ϕ = 0.05). The investigated geometry has one degree-of-freedom (DOF), the fin aspect ratio (H1/L1), which is varied in the range 0.1 ≤ H1/L1 ≤ 10. The aspect ratio of the cavity is maintained fixed (H/L = 1.0). The effect of the fin geometry over the Nusselt number is investigated for several Rayleigh (RaH = 103, 104, 105 and 106) and Reynolds numbers (ReH = 10, 102, 3.0 × 102, 5.0 × 102, 7.0 × 102 and 103). For all simulations, the Prantdl number is fixed (Pr = 0.71). The conservation equations of mass, momentum, and energy are numerically solved with the finite volume method. Results showed that fin geometry (H1/L1) has strong influence over the Nusselt number in the fin. It was also observed that the effect of H1/L1 over Nusselt number changes considerably for different Rayleigh numbers and for the lowest magnitudes of Reynolds numbers, for example, differences of nearly 770% between RaH = 106 and forced convective flow were observed for the lowest Reynolds number studied (ReH = 10).

scholarly journals Fluidodynamic Analysis of Cylindrical Particles in Fluidized Bed With Aspect Ratio Variation

2019 ◽  
Vol 40 (1) ◽  
pp. 23
Author(s):  
Dionisson de Andrade Michelotto ◽  
Paulo Roberto Wander
Keyword(s):  
Aspect Ratio ◽  
Fluidized Bed ◽  
Ratio Variation ◽  
Cylindrical Particles

A velocidade mínima do fluido nas partículas é um parâmetro hidrodinâmico que influencia fortemente o comportamento em projetos de reatores de leito fluidizado. A maioria dos trabalhos acadêmicos utiliza como um dos principais parâmetros em suas correlações a esfericidade. Outros estudos afirmam que a razão de aspecto influencia grandemente a velocidade mínima de fluidização. Utilizando um reator de leito fluidizado, partículas de bambu cilíndricas com razões de aspecto de 2, 4 e 6 foram fluidizadas. Os resultados das velocidades mínimas de fluidização foram comparados com outros autores, onde três foram suficientemente próximos dentro de uma variação de 20% dos valores obtidos nos experimentos. Uma nova correlação foi proposta variando-se a razão de aspecto onde os valores da fluidização mínima foram muito próximos aos da experimental.

scholarly journals Oscillatory rarefied gas flow inside rectangular cavities

2014 ◽  
Vol 748 ◽  
pp. 350-367 ◽  
Author(s):  
Lei Wu ◽  
Jason M. Reese ◽  
Yonghao Zhang
Keyword(s):  
Aspect Ratio ◽  
Gas Flow ◽  
Rarefied Gas ◽  
Scaling Law ◽  
Frequency Range ◽  
Damping Force ◽  
Driven Cavity ◽  
Linearized Boltzmann Equation ◽  
Wide Range ◽  
Oscillation Frequencies

AbstractTwo-dimensional oscillatory lid-driven cavity flow of a rarefied gas at arbitrary oscillation frequency is investigated using the linearized Boltzmann equation. An analytical solution at high oscillation frequencies is obtained, and detailed numerical results for a wide range of gas rarefaction are presented. The influence of both the aspect ratio of the cavity and the oscillating frequency on the damping force exerted on the moving lid is studied. Surprisingly, it is found that, over a certain frequency range, the damping is smaller than that in an oscillatory Couette flow. This reduction in damping is due to the anti-resonance of the rarefied gas. A scaling law between the anti-resonant frequency and the aspect ratio is established, which would enable the control of the damping through choosing an appropriate cavity geometry.

scholarly journals GEOMETRICAL EVALUATION OF RECTANGULAR FIN MOUNTED IN LATERAL SURFACE OF LID-DRIVEN CAVITY FORCED CONVECTIVE FLOWS

2019 ◽  
Vol 18 (2) ◽  
pp. 98
Author(s):  
E. D. dos Santos ◽  
P. M. Rodrigues ◽  
L. A. Isoldi ◽  
J. F. Prolo Filho ◽  
L. A. O. Rocha ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Thermal Performance ◽  
Degrees Of Freedom ◽  
Reynolds Numbers ◽  
Cavity Surface ◽  
Square Cavity ◽  
Driven Cavity ◽  
Convective Flows ◽  
Constructal Design ◽  
Volume Method

In this work, it is investigated the geometric effect of rectangular fin inserted in a lid-driven square cavity over thermal performance of laminar, incompressible, steady and forced convective flows. This study is performed by applying Constructal Design to maximize the heat transfer between the fin and the cavity flow. For that, the problem is subjected to two constraints: area of the cavity and area of rectangular fin, and two degrees of freedom: height/length ratio of rectangular fin (H1/L1) and its position in upstream surface of the cavity (S/A1/2). It is considered here some fixed parameters, as the ratio between the fin and cavity areas (ϕ = 0.05), the aspect ratio of the cavity dimensions (H/L = 1.0) and Prandtl number (Pr = 0.71). The fin aspect ratio (H1/L1) was varied for three different placements of the fin at the upstream cavity surface (S/A1/2 = 0.1, 0.5 and 0.9) which represents a lower, intermediate and upper positions of the fin. The effects of the fin geometry over the spatial-averaged Nusselt number ( ) is investigated for three different Reynolds numbers (ReH = 10, 102 and 103). The conservation equations of mass, momentum and energy were numerically solved with the Finite Volume Method. Results showed that both degrees of freedom (H1/L1 and S/A1/2) had a strong influence over , mainly for higher magnitudes of Reynolds number. Moreover, the best thermal performance is reached when the fin is placed near the upper surface of the cavity for an intermediate ratio between height and length of rectangular fin, more precisely when (S/A1/2)o = 0.9 and (H1/L1)oo = 2.0.

Moving Target Classification in Road Monitoring Based on Multi-Feature Fusion

2013 ◽  
Vol 401-403 ◽  
pp. 1208-1211
Author(s):  
Lin Wu ◽  
Xiao Pei Wu ◽  
Juan Xu
Keyword(s):  
Aspect Ratio ◽  
Classification Accuracy ◽  
Feature Fusion ◽  
Moving Target ◽  
Dynamic Feature ◽  
Connected Component ◽  
Target Classification ◽  
Connected Component Labeling ◽  
Ratio Variation ◽  
Target Extraction

A method for moving target classification in road monitoring based on multi-feature fusion is presented in this paper. In this method, connected component labeling and merging combined with morphology are used to achieve the target extraction. Static features in moving target are extracted. To improve the low classification accuracy, a dynamic feature, lower thirds aspect ratio variation (also named as LTVar), is proposed and added. The recognition ratio obtains the relative increasing of 3.1% compared with the static features.

Start-up flows in a three-dimensional rectangular driven cavity of aspect ratio 1:1:2 at Re = 1000

2002 ◽  
Vol 450 ◽  
pp. 169-199 ◽  
Author(s):  
J.-L. GUERMOND ◽  
C. MIGEON ◽  
G. PINEAU ◽  
L. QUARTAPELLE
Keyword(s):  
Aspect Ratio ◽  
Three Dimensional ◽  
High Sensitivity ◽  
Viscous Flows ◽  
Reynolds Numbers ◽  
Two Dimensions ◽  
Dimensionless Time ◽  
Driven Cavity ◽  
Start Up ◽  
Initial Evolution

This paper provides comparisons between experimental data and numerical results for impulsively started flows in a three-dimensional rectangular lid-driven cavity of aspect ratio 1:1:2 at Reynolds number 1000. The initial evolution of this flow is studied up to the dimensionless time t = 12 and is found both experimentally and numerically to exhibit high sensitivity to geometrical perturbations. Three different flow developments generated by very small changes in the boundary geometry are found in the experiments and are reproduced by the numerics. This indicates that even at moderate Reynolds numbers the predictability of three-dimensional incompressible viscous flows in bounded regions requires controlling the shape of the boundary and the values of the boundary conditions more carefully than needed in two dimensions.

Study of Natural Convection in Volumetrically Heated Enclosures for Different Aspect Ratios and Prandtl Numbers

2009 ◽  
Author(s):  
Parameshwar Deshmukh ◽  
Sushanta K. Mitra ◽  
U. N. Gaitonde
Keyword(s):  
Natural Convection ◽  
Aspect Ratio ◽  
Simple Algorithm ◽  
Driven Cavity ◽  
Aspect Ratios ◽  
Fluid Properties ◽  
Inclination Angles ◽  
Parametric Studies ◽  
Horizontal Cavity ◽  
Prandtl Numbers

Natural convection in volumetrically heated rectangular enclosures is studied in this work. The walls of the enclosure are maintained isothermal. For the rectangular enclosure, two-dimensional conservation equations are solved using SIMPLE algorithm. The code is benchmarked with the results for a lid-driven cavity and a differentially heated cavity. Parametric studies are conducted to examine the effects of orientation of the cavity, fluid properties (Pr number), and aspect ratio for Rayleigh numbers up to 106. For a horizontal cavity, the flow becomes periodically oscillating at Ra = 5×104 and chaotic at Ra = 8×105. With a slight increase in the inclination angle, the oscillations die down and for inclination angles greater than 15°, the flow attain a steady state over a range of Ra. The aspect ratio AR, defined as the ratio of the height to the width of the cavity, is varied from 0.25 to 0.75 (AR < 1: wide cavities) and from 2.0 to 6.0 (AR > 1: long cavities). The values of critical Ra at which the convection sets in the cavity are presented for the range of AR studied here. The corresponding flow regimes are also identified.

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