Begell House Inc.
International Journal of Fluid Mechanics Research
FMR
2152-5102
45
3
2018
DIFFERENT APPROACHES TO APPLYING POD ANALYSIS TO 3D3C DATA IN A LARGE MEASUREMENT VOLUME
187-201
10.1615/InterJFluidMechRes.2018020625
Redha
Wahidi
Department of Mechanical Engineering, University of Texas of the Permian Basin, Odessa, TX
Semih M.
Olcmen
Department of Aerospace Engineering and Mechanics, The University of Alabama,
Tuscaloosa, AL
James P.
Hubner
Department of Aerospace Engineering and Mechanics, The University of Alabama,
Tuscaloosa, AL
volumetric PIV
2D POD
3D POD
Proper orthogonal decomposition (POD) analysis is performed on volumetric three-component data of a threedimensional
flow field. A flow field with 3D vortical structures is selected to examine the "robustness" of the POD
analysis in a relatively large measurement domain. These POD results are evaluated in how well they capture the
vortical structures in the flow field. Moreover, the POD results of the entire domain are compared to POD analysis
applied to subdomains. The subdomain POD analyses include smaller 3D domains, and 2D planes with two or three
components of the velocity. Results of the POD analysis of the entire domain capture all the structures in the flow;
however, the vortical structures are identified more efficiently in the subdomains. The results also show that confining the subdomains in a direction where the vortices are continuous does not affect the POD spatial modes. The best results are obtained when the POD analysis is applied to a 2D plane perpendicular to the axis of rotation of the vortices. Moreover, a brief discussion is provided about the differences between POD analysis performed using a covariance matrix containing the three velocity vectors and using three covariance matrices for the three components of the vector.
THEORETICAL INVESTIGATION OF MHD CONVECTION NAVIER–STOKES FLOW OVER AN UNSTEADY STRETCHING SHEET
203-223
10.1615/InterJFluidMechRes.2018021116
Rehan Ali
Shah
Department of Basic Sciences and Islamiat, University of Engineering and Technology
Peshawar, Peshawar, KPK, Pakistan
Sajid
Rehman
Islamia College Peshawar
M.
Idrees
Department of Mathematics, Islamia College Peshawar, Khyber Pakhtoon Khwa, Pakistan
Tariq
Abbas
Department of Basic Sciences, Sarhad University Peshawar, Khyber Pakhtoon Khwa, Pakistan
HAM
thermocapillary number
magnetic field
thin film
free surface flow
unsteady stretching surface
similarity transformations
Grashof number
In this paper, electrically conducted Newtonian flow under nonisothermal condition over an unsteady stretching sheet
is studied. We considered the effect of a magnetic field normal to the direction of the flow while surface tension linearly varied with temperature. The boundary layer Navier–Stokes and energy equations in Cartesian coordinates are
transformed into a system of nonlinear ordinary differential equations (ODEs) by the similarity transformation. Clear
observation is made between the study of our previous two papers and the present work for the obtained values of ϒ and f ''(0), while comparison of the values β = ϒ1/2, f '(1), and f ''(1) is observed between the present work and the work of the previous two papers. Analyses are carried out by means of the homotopy analysis method (HAM) up to a satisfactory order of approximations via Mathematica package BVPh2.0. Here the nondimensional Grashof number gives the relative strength, i.e., which force is dominating, because it is the ratio of buoyancy force to viscous force. Effects of nondimensional values such as unsteadiness parameter S, Hartmann number Ma, skin friction f''(0), Prandtl number Pr, thermocapillary number M, heat flux − θ'(0), free surface temperature θ(1), and the Grashof number Gr are discussed and presented graphically.
EFFECT OF SUBMERGENCE AND FLOW RATE ON FREE SURFACE VORTICES IN A PUMP SUMP
225-236
10.1615/InterJFluidMechRes.2018020379
Byeongrog
Shin
Department of Mechanical Design Systems Engineering, University of Miyazaki, Miyazaki
889-2192, Japan
pump sump
submergence depth
vortex length
free surface vortex
air-water interface
numerical analysis
Free surface vortices formed around an intake pipe in a pump sump can have a significant effect on the pump performance. The objective of this study is to investigate the effect of the submergence and flow rate on free surface vortices using numerical simulations. A finite volume method with a Reynolds-averaged Navier-Stokes turbulence model and
a volume of fluid multiphase model was applied to solve the free surface flow in the sump with a single intake channel. A multiblocked structured grid system is used to capture the behavior and interaction of flow between two fluid
phases with higher accuracy. The minimum elevation of air-water interface, air-entrained vortex length, and the volume
rendering method are used to identify the location and shape of the free surface as well as free surface vortices. By investigating the air-water interface with a variation in submergence and flow rate, it was found that lower submergences or larger flow rates induce stronger free surface vortices to appear. The locations of the center core of surface vortices were predicted by the interface tracking method, and they were in good agreement with those of the experiments.
MIXED CONVECTION AND ENTROPY GENERATION OF A NANOFLUID FILLED CAVITY WITH A CORNER PARTITION AND FLEXIBLE WALL
237-253
10.1615/InterJFluidMechRes.2018022470
Fatih
Selimefendigil
Mechanical Engineering Department, Celal Bayar University, Manisa, 45140, Turkey
Hakan F.
Öztop
Department of Mechanical Engineering, Technology Faculty, Firat University, Elazig, Turkey; Mechanical Engineering Department, Faculty of Engineering, King Abdulaziz University,
P.O. Box 40844, Jeddah 21511, Saudi Arabia
corner partition
flexible wall
nanofluid
finite element method
In this study, the effects of a conductive corner partition and flexible sidewall in a CuO-water nanofluid-filled liddriven square enclosure on mixed convective heat transfer were numerically examined using the finite element method.
The top wall of the square cavity is moving with constant speed and the bottom wall of the cavity is heated. The side
wall is made flexible. The effects of the Richardson number (between 0.01 and 20), elastic modulus of the flexible wall
(between 103 and 105), size of the corner partition (between 0 and 0.6), and solid particle volume fraction (between 0 and 0.05) on the fluid flow, heat transfer characteristics and entropy generation rate were numerically investigated. It was observed that local and average heat transfer enhances for higher values of the Richardson number, elastic modulus of the flexible wall and solid particle volume fraction of the nanoparticles. An average heat transfer enhancement of 38.34% was obtained when the elastic modulus of the flexible wall was reduced from 105 to 103, and 32.10% of the
average Nusselt number enhancement was obtained for 5% nanoparticle addition to the base fluid. The presence of the
conductive corner partition deteriorated the local and average heat transfer, and average heat transfer reduction for 23.78% of was observed for a partition size of 0.6. Entropy generation rates for the fluid domain and solid domain of the conductive partition were found to be affected by the variation of those parameters.
ENTRANCE LENGTH AND FRICTION FACTOR CORRELATIONS FOR TURBULENT FLOW IN CONCENTRIC ANNULI
255-262
10.1615/InterJFluidMechRes.2018020326
Biswadip
Shome
Global Technology and Engineering Center, Offices No. 501 & No. 502, D Block, Weikfield IT Citi Info Park, Pune-Nagar Road, Pune, India 411014
turbulent flow
concentric annuli
entrance length correlation
friction factor correlation
Fully developed turbulent flow in a concentric annulus was investigated using the k-ω shear stress transport turbulence model. The investigation was conducted for a Reynolds number range of 5000–80,000 and an annulus diameter ratio range of 1.1–25. Correlations to predict the entrance length and the friction factors to respective accuracy of 3.1% and 2% are proposed.
NUMERICAL SIMULATION AND FUNDAMENTAL CHARACTERISTICS OF SURFACE FLOW GENERATED BY BUBBLY FLOWS
263-282
10.1615/InterJFluidMechRes.2018021875
Hassan
Abdulmouti
Department of Mechanical Engineering Division, Sharjah Men's College, Higher Colleges of Technology, P.O. Box 7946, Sharjah, United Arab Emirates
multiphase flow
bubble flow
surface flow
numerical simulation
Eulerian-Lagrangian model
bubble
free surface
The motivation of this paper is to determine the characteristics of the surface flow induced by a bubble plume, which depends on the gas flow rate, bubble size, and internal two-phase flow structure of the bubbly flow. This paper is concerned with the numerical analysis of a surface flow generation process by buoyant bubbles in the two-dimensional and three-dimensional flow analysis based on the Eulerian-Lagrangian model. This is formulated with emphasis on the translational motion of bubbles. The technique of utilizing a surface flow generated by a bubbly flow could be employed as an effective way to control and collect the surface-floating substances in naval systems, lakes, seas, rivers, and oceans, as well as in various kinds of engineering processes involving a free surface. However, the detailed mechanism of the surface flow generation process has not previously been measured. The aim of this study is to clarify the applicability of a bubbling jet flow in order to control the transportation of surface-floating substances on a free surface. The numerical results presented in this paper reveal the characteristics of the fluid dynamics in the surface flow generation process. Furthermore, parametric dependency of the surface flow structure on the bubbling conditions is shown. The results presented in this paper clarify that the surface velocity profile that can be predicted by the Eulerian-Lagrangian model
is in good agreement with the results of the experiments shown in our earlier paper. The surface flow is effectively
generated in the case of a bubble plume compared to a liquid jet flow because a distortion point appears in the vicinity
of the surface. The study also illustrates that the effective thickness of the surface flow is much less in the case of a free surface than in the case of a nonslip condition. The effective thickness of the surface flow increases when a liquid jet flow is provided instead of the bubble plume. The surface flow involves a wavy fluctuation under the free surface.