Maximum Air Suction Into a Louvered Funnel Through Optimum Design

2012 ◽  
Vol 56 (01) ◽  
pp. 1-11 ◽  
Author(s):  
Dipti P. Mishra ◽  
Sukanta K. Dash
Keyword(s):  
Reynolds Number ◽  
Pipe Flow ◽  
Numerical Experiments ◽  
Simple Relation ◽  
Maximum Amount ◽  
Fluid Temperature ◽  
Entrance Length ◽  
A Value ◽  
Suction Rate ◽  
Flow Case

The rate of air suction into a louvered cylindrical funnel with lateral openings has been computed numerically by solving the equations of conservation of mass, momentum, and energy along with the two k-z turbulence closure equations. It was found that the air suction rate into a louvered funnel can be maximum for an optimum nozzle protrusion length into the funnel irrespective of the nozzle fluid temperature. There also exists an optimum funnel diameter (irrespective of the nozzle fluid temperature) and funnel height for which the air suction rate can be the maximum. Keeping the volume of the funnel constant, the shape of the funnel was changed to a frustum. It was found that an inverted frustum with a value of r1/r2 = 0.8 could suck the maximum amount of air compared to a cylindrical funnel of the same volume. The cylindrical sucking funnel has interestingly a much shorter entrance length compared to a simple pipe flow case with the same entrance Reynolds number. The entrance length for the sucking funnel is also a function of the nozzle fluid temperature, and a simple relation for the entrance length as a function of Ren and Tn/T∞ could also be developed for a sucking funnel. Numerical experiments were done for an inclined funnel to compute the mass suction into it. It was found that for Gr/Re2 ≤ 0.4 (where Gr is the Grashof number and Re is the Reynolds number) given by the funnel inclination had no effect on the rate of mass suction while for 0.4 < Gr/Re2 < 1 the funnel inclination had marginal influence. As the value of Gr/Re2 increased beyond 1 the influence of the funnel inclination on rate of mass suction was found to be significant.

scholarly journals Hydro Magnetic Effect on Thread Stretching Surface with Mounted Obstacles in Porous Medium

2021 ◽  
Vol 16 ◽  
pp. 95-105
Author(s):  
Mohammad Mohsen Peiravi ◽  
Pooya Pasha ◽  
Davood Domairry Ganji
Keyword(s):  
Magnetic Field ◽  
Finite Element ◽  
Fluid Flow ◽  
Stretching Sheet ◽  
Flow Behavior ◽  
Maximum Amount ◽  
Maximum Temperature ◽  
Fluid Temperature ◽  
A Value ◽  
Fluid Concentration

In this paper, Finite element Model is applied for investigation of fluid flow over a stretching sheet in existence of magnetic field. Finite element method is applied to find the influence of melting heat transfer on fluid flow behavior over a stretching sheet in presence of magnetic field. we investigated the flow of fluid flowing through the fins plate under the influence of the magnet. The fins were on the board and the end of the plate. In the case of chamfer fins, the maximum temperature variation is observed. In this fins, the maximum temperature of T = 2.5 and minimum temperature is T = 3. in general, we conclude that the temperature flow around the rectangular fins has a maximum value than 2 other modes. In triangular fins, the fluid temperature vector around the fins has more intensity than other modes and the temperature gradient around it is larger than the previous one and the fluid flow at the end of the plate also has more temperature than the Rectangular fins. The maximum amount of fluid concentration has been observed around the first fin of chamfer mode in range of X=0.05 to X=0.1. In general, the fluid concentration around the triangular fins is higher than other modes. the maximum amount of fluid concentration is found in the triangular fins on the surface. Their concentration from the first fin reaches a value of 2.5 and in the last fin at a value of 1.4.

A STUDY OF THE MUTUAL INFLUENCE OF Cs AND S ON Si(100)-(2 × 1) SURFACES

2002 ◽  
Vol 09 (03n04) ◽  
pp. 1475-1483
Author(s):  
A. C. PAPAGEORGOPOULOS
Keyword(s):  
Mutual Influence ◽  
Structural Models ◽  
Maximum Amount ◽  
Site Preference ◽  
Semiconductor Substrate ◽  
Low Energy Electron Diffraction ◽  
A Value ◽  
Initial Decrease ◽  
Low Energy Electron ◽  
S Deposition

In this work we study the adsorption of Cs on S-covered Si(100)-(2 × 1) and Si(100)-(1 × 1) surfaces, as well as the adsorption of S on Cs-covered Si(100)-(2 × 1). The experiment was performed in an ultrahigh vacuum (UHV) chamber with low energy electron diffraction (LEED), Auger electron spectroscopy (AES) and work function (WF) measurements. Predeposited S increases the binding energy and the maximum amount of Cs that can be deposited on the surface. The presence of S inhibits the pattern of the characteristic WF curve of Cs on clean Si(100)-(2 × 1), i.e. an initial decrease to a minimum value, Φmin, followed by an increase toward the value Φmax of metallic Cs. The WF, instead, decreases to a value close to that of saturated Cs on clean Si(100)-(2 × 1), where it forms a plateau. This is characteristic of the covalent bonding of Cs with the semiconductor substrate. Independently of the sequence of Cs and S deposition, (a) the transition Si(100)-(2 × 1) → Si(100)-(1 × 1) occurs when ΘS > 0.5 ML, and (b) the sites of Cs and S remain the same, with the Cs atoms residing between the S atoms. Heating of the S/Cs/Si composite surfaces to ~ 650 K causes a reorganization of the Cs and S adatoms in a tendency to form a Cs–S complex. The issue of site preference for Cs and S adatoms has been discussed in detail in the structural models provided.

scholarly journals Video: DNS of turbulent pipe flow at high Reynolds number

2021 ◽  
Author(s):  
Alessandro Ceci ◽  
Sergio Pirozzoli ◽  
Joshua Romero ◽  
Massimiliano Fatica ◽  
Roberto Verzicco ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Pipe Flow ◽  
High Reynolds Number ◽  
Turbulent Pipe Flow ◽  
High Reynolds

Empirical Estimates of Body Drag of Large Waterfowl and Raptors

1988 ◽  
Vol 135 (1) ◽  
pp. 253-264 ◽  
Author(s):  
C. J. PENNYCUICK ◽  
HOLLIDAY H. OBRECHT ◽  
MARK R. FULLER
Keyword(s):  
Reynolds Number ◽  
Reynolds Numbers ◽  
The Body ◽  
Number Range ◽  
Empirical Estimates ◽  
A Value ◽  
Body Drag ◽  
Wind Tunnel Measurements ◽  
Large Living ◽  
Performance Estimates

To whom reprint requests should be addressed. Measurements of the body frontal area of some large living waterfowl (Anatidae) and raptors (Falconiformes) were found to vary with the two-thirds power of the body mass, with no distinction between the two groups. Wind tunnel measurements on frozen bodies gave drag coefficients ranging from 0.25 to 0.39, in the Reynolds number range 145 000 to 462 000. Combining these observations with those of Prior (1984), which extended to lower Reynolds numbers, a practical rule is proposed for choosing a value of the body drag coefficient for use in performance estimates.

The effect of rigid rotation on the finite-amplitude stability of pipe flow at high Reynolds number

1984 ◽  
Vol 148 ◽  
pp. 193-205 ◽  
Author(s):  
T. R. Akylas ◽  
J.-P. Demurger
Keyword(s):  
Reynolds Number ◽  
Pipe Flow ◽  
High Reynolds Number ◽  
Finite Amplitude ◽  
Linear Instability ◽  
Rigid Rotation ◽  
Transition To Turbulence ◽  
Neutral Stability ◽  
Axisymmetric Mode ◽  
High Reynolds

A theoretical study is made of the stability of pipe flow with superimposed rigid rotation to finite-amplitude disturbances at high Reynolds number. The non-axisymmetric mode that requires the least amount of rotation for linear instability is considered. An amplitude expansion is developed close to the corresponding neutral stability curve; the appropriate Landau constant is calculated. It is demonstrated that the flow exhibits nonlinear subcritical instability, the nonlinear effects being particularly strong owing to the large magnitude of the Landau constant. These findings support the view that a small amount of extraneous rotation could play a significant role in the transition to turbulence of pipe flow.

Numerical Research of Roughness Effects on Flow and Heat Transfer Characteristics in Flat Microchannels

2009 ◽  
Author(s):  
Heming Yun ◽  
Baoming Chen ◽  
Binjian Chen
Keyword(s):  
Heat Transfer ◽  
Surface Roughness ◽  
Reynolds Number ◽  
Conjugate Heat Transfer ◽  
Entrance Length ◽  
Heat Transfer Characteristics ◽  
Roughness Effects ◽  
Relative Roughness ◽  
Flow And Heat Transfer ◽  
Numerical Research

Roughness effects on flow and heat transfer in flat microchannels has been numerically simulated by using CFD with fluid-solid conjugate heat transfer techniques, the surface roughness has been modeled through a series triangular toothed roughness cells. In this paper, the influence for roughness on the entrance length of flow and heat transfer has been emphasized, the influence for relative roughness on transitional Reynolds number has been also analyzed at the same time.

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