Theoretical Study of the Laminar Flow in a Channel With Moving Bars

2009 ◽  
Vol 131 (11) ◽  
Author(s):  
Hai-Ping Hu ◽  
Rong-Hua Yeh
Keyword(s):  
Laminar Flow ◽  
Cross Section ◽  
Eigenfunction Expansion ◽  
Theoretical Study ◽  
Reverse Flow ◽  
Governing Equations ◽  
Match Method ◽  
Poisson Equations ◽  
Aspect Ratios ◽  
The Mean

This paper presents a study of the laminar flow in a channel with longitudinal moving bars arrayed along the channel width. The governing equations describing the fluid, which flows along the direction of the bar’s length, are expressed with double Poisson equations and are solved by eigenfunction-expansion and point-match method. The result shows that when the solid bars move forward, the fluid flow will move in the same direction, and the f Re decreases as the positive velocity of bars increases. However, when the bars move backward, a reverse flow will occur in the channel, and the f Re is higher at larger negative velocity of bars. For a channel flow with moving bars, the f Re value is not a constant, such as a classical one without moving bars, in which the f Re value is a constant. Furthermore, when the area of the cross section of the bar is fixed, both the mean velocities and the f Re values of the fluid can be obtained under different velocities and aspect ratios of the bars.

Heat Transfer for Laminar Flow in Spiral Ducts of Rectangular Cross Section

2005 ◽  
Vol 127 (3) ◽  
pp. 352-356 ◽  
Author(s):  
Michael W. Egner ◽  
Louis C. Burmeister
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Laminar Flow ◽  
Cross Section ◽  
Rectangular Cross Section ◽  
Three Dimensional ◽  
Radius Of Curvature ◽  
Dean Number ◽  
Aspect Ratios ◽  
Small Pitch

Laminar flow and heat transfer in three-dimensional spiral ducts of rectangular cross section with aspect ratios of 1, 4, and 8 were determined by making use of the FLUENT computational fluid dynamics program. The peripherally averaged Nusselt number is presented as a function of distance from the inlet and of the Dean number. Fully developed values of the Nusselt number for a constant-radius-of-curvature duct, either toroidal or helical with small pitch, can be used to predict those quantities for the spiral duct in postentry regions. These results are applicable to spiral-plate heat exchangers.

Flow in a Channel With Longitudinal Ribs

1994 ◽  
Vol 116 (2) ◽  
pp. 233-237 ◽  
Author(s):  
C. Y. Wang
Keyword(s):  
Reynolds Number ◽  
Eigenfunction Expansion ◽  
Complex Geometry ◽  
Parallel Plates ◽  
Match Method ◽  
Mean Velocity ◽  
Longitudinal Ribs ◽  
Flow Through ◽  
The Mean ◽  
Wetted Perimeter

The laminar, viscous flow between parallel plates with evenly spaced longitudinal ribs is solved by an eigenfunction expansion and point-match method. The ribs on both plates may be symmetrically placed or staggered. For a given pressure gradient, the mean velocity is plotted as a function of the geometric parameters. We find the wetted perimeter and the friction factor—Reynolds number product are unsuitable parameters for the flow through ducts of complex geometry.

Heat Transfer for Laminar Flow in a Curved Pipe

1968 ◽  
Vol 90 (3) ◽  
pp. 313-318 ◽  
Author(s):  
M. N. O¨zisik ◽  
H. C. Topakog˘lu
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Laminar Flow ◽  
Cross Section ◽  
Series Expansion ◽  
Internal Heat ◽  
Internal Heat Generation ◽  
Curved Pipe ◽  
The Mean ◽  
Analytical Expressions

Heat transfer for hydrodynamically and thermally fully developed laminar flow in a curved pipe is solved by a method of series expansion. The wall temperature around the periphery of any cross section, the mean heat flux along the pipe, and the internal heat generation are assumed to be uniform. The first few terms of the series expansion are determined and analytical expressions for the temperature distribution in the fluid and for the Nusselt number are presented; the results are applicable for small curvatures. A correlation with experiment is included.

Numerical Procedure for the Laminar Developed Flow in a Helical Square Duct

2005 ◽  
Vol 127 (1) ◽  
pp. 136-148 ◽  
Author(s):  
V. D. Sakalis ◽  
P. M. Hatzikonstantinou ◽  
P. K. Papadopoulos
Keyword(s):  
Laminar Flow ◽  
Friction Factor ◽  
Cross Section ◽  
Numerical Procedure ◽  
Governing Equations ◽  
Axial Pressure ◽  
Dean Number ◽  
Square Duct ◽  
Orthogonal Coordinate System ◽  
Axial Pressure Gradient

The incompressible fully developed laminar flow in a helically duct of square cross section is studied expressing the governing equations in terms of an orthogonal coordinate system. Numerical results are obtained with the described continuity, vorticity, and pressure (CVP) numerical method using a colocation grid for all variables. Since there are not approximations, the interaction effects of curvature, torsion and axial pressure gradient on the velocity components and the friction factor are presented. The results show that the torsion deforms substantially the symmetry of the two centrifugal vortices of the secondary flow, which for large values of torsion combined with small curvature tend to one vortex covering the whole cross section. The friction factor decreases for torsion in the range 0 to 0.1 and increases as the torsion increases further, a behavior which is more profound as the Dean number increases. Our results are stable for the calculated Dean numbers.

scholarly journals HYDRODYNAMIC ANALYSES OF THE FLOW PATTERNS IN STIRRED VESSEL OF TWO-BLADED IMPELLER

2020 ◽  
Vol 14 (2) ◽  
pp. 117-132
Author(s):  
Houssem Laidoudi
Keyword(s):  
Reynolds Number ◽  
Fluid Flow ◽  
Laminar Flow ◽  
Cross Section ◽  
Rotational Speed ◽  
Circular Cross Section ◽  
Three Dimensions ◽  
Governing Equations ◽  
Stirred Vessel ◽  
New Correlation

In this paper, the governing equations of continuity and momentum subjected to suitable boundary conditions have been solved numerically to investigate the fluid flow in stirred vessel of two-bladed impeller. The numerical simulations have been carried out in three-dimensions for laminar flow. The studied fluid was considered Newtonian and incompressible. Our research studied the effects of geometrical configurations of the two-bladed impeller and its rotational speed on fluid patterns and mechanical power consumption. The innovative point in this paper is that the blades of the impeller contain three equal-sized holes of circular cross-section. The diameter of the hole (d) to the impeller diameter (D) gives the ratio d/D. the impeller speed is controlled by the Reynolds number (Re). The obtained results have been illustrated and discussed for the range of following governing parameters: d/D = 0 to 0.4 and Re = 1 to 300. The results showed that the studied parameters have significant effects on fluid flow and consumption power and the perforated blades of ratio d/D = 0.133 is more efficient than plan blades. Also, a new correlation is proposed to describe the consumption power as function of d/D and Re.

Laminar Flow and Heat Transfer in Spiral Ducts of Rectangular Cross Section

2004 ◽  
Author(s):  
Michael W. Egner ◽  
Louis C. Burmeister
Keyword(s):  
Heat Transfer ◽  
Laminar Flow ◽  
Cross Section ◽  
Rectangular Cross Section ◽  
Three Dimensional ◽  
Radius Of Curvature ◽  
Dean Number ◽  
Flow And Heat Transfer ◽  
Aspect Ratios ◽  
Small Pitch

Laminar flow and heat transfer in three-dimensional spiral ducts of rectangular cross section with aspect ratios of 1, 4, and 8 were determined with the aide of the FLUENT computational fluid dynamics program. Peripherally-averaged coefficients of friction and Nusselt numbers are presented as a function of distance from the inlet and of the Dean number. Fully-developed values of friction coefficient and Nusselt number for a constant-radius-of-curvature duct, either toroidal or helical with small pitch, can be used to predict those quantities for the spiral duct in post-entry regions. These results are applicable to spiral-plate heat exchangers.

IMPROVING STUDENT’S VOCABULARY ACHIEVEMENT THROUGH “MAKE A MATCH METHOD”

2013 ◽  
Vol 2 (4) ◽  
Author(s):  
Ade Iriyani And Sortha Silitonga
Keyword(s):  
Action Research ◽  
Quantitative Data ◽  
Qualitative Data ◽  
English Teacher ◽  
Match Method ◽  
Class Viii ◽  
The Mean ◽  
Second Year ◽  
Teacher Use ◽  
Vocabulary Achievement

The objective of the study is to find out if the students’ vocabulary achievement improved through Make a Match Method. The research of this study was conducted by using action research. The subjects of this study were the second year students of MTs Swasta Al-Badar Tanjungbalai class VIII consisted of 31 students. The research was conducted in two cycles and every cycle consisted of three meetings. Quantitative and qualitative instruments were used to gather the data. Quantitative data was taken from the students’ score in vocabulary mastery, while qualitative data was taken from diary notes, observation sheets and questionnaire sheets. Based on the data, the students’ scores got improvement in every cycle. In test I, the mean of the students’ score was 59 while test II, the mean of the students’ score was 70.5 and in test III the mean of the students’ score was 77.3. It was found that the teaching vocabulary through Make a Match Method improve the students’ vocabulary Achievement. It is suggested that English teacher use Make a Match Method as one of alternatives method in teaching vocabulary.

Computational and theoretical research of the injector block function

2020 ◽  
pp. 123-126
Author(s):  
В.В. Кожемякин ◽  
Р.А. Иванов ◽  
Е.С. Игнатьева
Keyword(s):  
Hydraulic Resistance ◽  
Cross Section ◽  
Flow Rate ◽  
Pressure Dependence ◽  
Theoretical Study ◽  
Water Jet ◽  
Theoretical Research ◽  
Sudden Expansion ◽  
Operating Modes ◽  
Coefficient Of Hydraulic Resistance

Работа посвящена расчетно-теоретическому исследованию работы блока инжекторов. Рассмотрен пароводяной струйный аппарат, который применяется в качестве средства циркуляции теплоносителя первого контура. Подвод дополнительного потока осуществляется на цилиндрическом участке с внезапным расширением сечения через перемычку. Для достижения поставленной цели разработана программа для ЭМВ, в которой смоделирована зависимость давления от нагрузки в контуре, а также проведено расчетно-теоретическое исследование влияние гидравлического сопротивления на расход перемычки. В данной работе рассмотрены только рабочие режимы, т.е. все инжекторы работают как насосы. В ходе работы было установлено, что при нагрузке в 30% увеличиваются коэффициенты инжекции пароводяного струйного аппарата, но характер работы перемычек не меняется. Так же было установлено, что расход через перемычку меняется не пропорционально коэффициенту гидравлического сопротивления перемычки. The paper is devoted to the computational and theoretical study of the injector block operation. A steam-water jet apparatus is considered, which is used as a means of circulating the primary circle coolant. The additional flow is supplied on the cylindrical section with a sudden expansion of the cross-section through the bridge. To achieve this goal, a computer program was developed that modeled the pressure dependence on the load in the circuit, and also a theoretical study of the influence of hydraulic resistance on the flow of the jumper was conducted. In this paper, only operating modes are considered, i.e. all the injectors function as pumps. In the process of the research, it was found that at a load of 30%, the injection coefficients of the steam-water jet apparatus increase, but the nature of the work of the jumpers does not change. It was also found out that the flow rate through the jumper does not change in proportion to the coefficient of hydraulic resistance of the jumper.

Approximate Calculation of Pressure Drop in Laminar Flow of Generalized Newtonian Liquid Through Channel of Noncircular Cross Section

1994 ◽  
Vol 59 (3) ◽  
pp. 603-615 ◽  
Author(s):  
Václav Dolejš ◽  
Ivan Machač ◽  
Petr Doleček
Keyword(s):  
Pressure Drop ◽  
Laminar Flow ◽  
Numerical Solution ◽  
Cross Section ◽  
Approximate Calculation ◽  
Newtonian Liquid ◽  
Straight Channel ◽  
Suggested Procedure ◽  
Noncircular Cross Section ◽  
Calculation Results

The paper presents a modification of the equations of Rabinowitsch-Mooney type for an approximate calculation of pressure drop in laminar flow of generalized Newtonian liquid through a straight channel whose cross section forms a simple continuous area. The suitability of the suggested procedure of calculation of pressure drop is demonstrated by the comparison of calculation results with both the published and original results of numerical solution and experiments.

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