Effect of Container Wall Friction on the Consolidation of Clay Specimen

IFCEE 2015 ◽  
2015 ◽  
Author(s):  
Owais S. Mir ◽  
Yashwant A. Kolekar ◽  
Dasaka S. Murty ◽  
B. V. S. Viswanadham
Keyword(s):  
Wall Friction ◽  
Container Wall

Quantitative effects of projectile-launch tube wall friction on ballistic tange operation

AIAA Journal ◽  
2000 ◽  
Vol 38 ◽  
pp. 1709-1715
Author(s):  
Akihiro Sasoh ◽  
Shinji Ohba ◽  
Kazuyoshi Takayama
Keyword(s):  
Tube Wall ◽  
Wall Friction ◽  
Launch Tube

Application of generalized Fourier heat conduction law on MHD viscoinelastic fluid flow over stretching surface

2019 ◽  
Vol 30 (6) ◽  
pp. 3481-3496 ◽  
Author(s):  
Arif Hussain ◽  
Muhammad Yousaf Malik ◽  
Mair Khan ◽  
Taimoor Salahuddin
Keyword(s):  
Heat Flux ◽  
Fluid Flow ◽  
Friction Factor ◽  
Numerical Technique ◽  
Wall Heat Flux ◽  
Constitutive Law ◽  
Wall Friction ◽  
Theoretical Physics ◽  
Stretching Surface ◽  
Content Type

Purpose The purpose of current flow configuration is to spotlights the thermophysical aspects of magnetohydrodynamics (MHD) viscoinelastic fluid flow over a stretching surface. Design/methodology/approach The fluid momentum problem is mathematically formulated by using the Prandtl–Eyring constitutive law. Also, the non-Fourier heat flux model is considered to disclose the heat transfer characteristics. The governing problem contains the nonlinear partial differential equations with appropriate boundary conditions. To facilitate the computation process, the governing problem is transmuted into dimensionless form via appropriate group of scaling transforms. The numerical technique shooting method is used to solve dimensionless boundary value problem. Findings The expressions for dimensionless velocity and temperature are found and investigated under different parametric conditions. The important features of fluid flow near the wall, i.e. wall friction factor and wall heat flux, are deliberated by altering the pertinent parameters. The impacts of governing parameters are highlighted in graphical as well as tabular manner against focused physical quantities (velocity, temperature, wall friction factor and wall heat flux). A comparison is presented to justify the computed results, it can be noticed that present results have quite resemblance with previous literature which led to confidence on the present computations. Originality/value The computed results are quite useful for researchers working in theoretical physics. Additionally, computed results are very useful in industry and daily-use processes.

Experiments on Flame Flashback in a Quasi-2D Turbulent Wall Boundary Layer for Premixed Methane-Hydrogen-Air Mixtures

2010 ◽  
Author(s):  
Christian Eichler ◽  
Thomas Sattelmayer
Keyword(s):  
Boundary Layer ◽  
Boundary Layers ◽  
Turbulent Flows ◽  
Turbulent Transport ◽  
Wall Friction ◽  
Evaluation Procedure ◽  
Wall Boundary Layer ◽  
Wall Boundary ◽  
Flame Flashback ◽  
Turbulent Wall

Premixed combustion of hydrogen-rich mixtures involves the risk of flame flashback through wall boundary layers. For laminar flow conditions, the flashback mechanism is well understood and is usually correlated by a critical velocity gradient at the wall. Turbulent transport inside the boundary layer considerably increases the flashback propensity. Only tube burner setups have been investigated in the past and thus turbulent flashback limits were only derived for a fully-developed Blasius wall friction profile. For turbulent flows, details of the flame propagation in proximity to the wall remain unclear. This paper presents results from a new experimental combustion rig, apt for detailed optical investigations of flame flashbacks in a turbulent wall boundary layer developing on a flat plate and being subject to an adjustable pressure gradient. Turbulent flashback limits are derived from the observed flame position inside the measurement section. The fuels investigated cover mixtures of methane, hydrogen and air at various mixing ratios. The associated wall friction distributions are determined by RANS computations of the flow inside the measurement section with fully resolved boundary layers. Consequently, the interaction between flame back pressure and incoming flow is not taken into account explicitly, in accordance with the evaluation procedure used for tube burner experiments. The results are compared to literature values and the critical gradient concept is reviewed in light of the new data.

Plastic Forming Processes Through Rotating Conical Dies1

2001 ◽  
Vol 68 (6) ◽  
pp. 894-902 ◽  
Author(s):  
D. Durban ◽  
G. Davidi ◽  
D. Lior
Keyword(s):  
Single Phase ◽  
Large Strain ◽  
Single Layer ◽  
Wall Friction ◽  
Nonlinear Ordinary Differential Equations ◽  
Tube Forming ◽  
Perfectly Plastic ◽  
Governing System ◽  
Plastic Forming ◽  
Exact Relations

Drawing and extrusion of single-phase and multilayered tubes through rotating conical dies is investigated within the framework of continuum plasticity. Large strain perfectly plastic J2 flow theory models constitutive behavior along with a radial-helical flow pattern. The governing system for a single-layer process is reduced to three coupled nonlinear ordinary differential equations. An approximate solution is developed for long and tapered working zones with low wall friction. That solution is used to simulate the field within each layer in composite tube forming. Exact relations are derived for the n-layered tube and it is shown that wall rotation can considerably reduce the required working loads. Dedicated to Professor Dietmar Gross on the occasion of his 60th birthday

Charts for water hammer in pipelines resulting from valve closure from full opening only

1985 ◽  
Vol 12 (2) ◽  
pp. 241-264 ◽  
Author(s):  
Bryan W. Karney ◽  
Eugen Ruus
Keyword(s):  
Good Accuracy ◽  
Pipe Wall ◽  
Pressure Head ◽  
Wall Friction ◽  
Maximum Pressure ◽  
Valve Closure ◽  
Closure Time ◽  
Basic Parameters ◽  
Valve Opening ◽  
Open Position

Maximum pressure head rises, which result from total closure of the valve from an initially fully open position, are calculated and plotted for the valve end and for the midpoint of a simple pipeline. Uniform, equal-percentage, optimum, and parabolic closure arrangements are analysed. Basic parameters such as pipeline constant, relative closure time, and pipe wall friction are considered with closures from full valve opening only. The results of this paper can be used to draw the maximum hydraulic grade line along the pipe with good accuracy for the closure arrangements considered. It is found that the equal-percentage closure arrangement yields consistently less pressure head rise than does the parabolic closure arrangement. Further, the optimum closure arrangement yields consistently less head rise than the equal-percentage one. Uniform closure produces pressure head rise that usually lies between those produced by the parabolic and the equal-percentage closure arrangements, except for the range of low pressure head rise combined with low or zero friction, where the rise due to uniform closure approaches that produced by optimum closure.

PSEUDOSTATIC DESIGN FACTORS FOR STABILITY OF WATERFRONT-RETAINING WALL DURING EARTHQUAKE

2010 ◽  
Vol 04 (04) ◽  
pp. 387-400 ◽  
Author(s):  
DEEPANKAR CHOUDHURY ◽  
SYED MOHD AHMAD
Keyword(s):  
Retaining Wall ◽  
Pressure Ratio ◽  
Free Water ◽  
Hydrodynamic Pressure ◽  
Wall Friction ◽  
Sliding Stability ◽  
The Stability ◽  
Seismic Forces ◽  
Design Factors ◽  
Similar Kind

The paper presents a methodology for seismic design of rigid watferfront-retaining wall and proposes simple design factors for the sliding stability under seismic condition. Conventional pseudostatic approach has been used for the calculation of the seismic forces, while for the calculation of the hydrodynamic pressure, Westergaard's approach has been used. In addition, the hydrodynamic force has been considered from both the upstream and downstream sides of the waterfront-retaining wall under free water condition of the backfill. Simplified expression for the calculation of the equivalent weight of the wall which would be needed to maintain sliding stability is presented. It has been observed that the presence of water both on the upstream and downstream sides of the wall has serious destabilizing effect on the stability of the wall. It is noticed that as the height of the water inside the backfill increased from 0.00 to a height equal to the height of the wall itself, i.e., the backfill is fully submerged, the weight of the wall needed for the later case is around 3 times more than what would be needed for the former case. Similar observations were also made by varying other parameters like the horizontal and vertical seismic acceleration coefficients, height of the water on the upstream side of the wall, and soil and wall friction angles. The pore pressure ratio and the inclination of the ground, however, did not have significant effect on the results. Due to nonavailability of the results of similar kind in literature, an exact comparison for the present results could not be made. Only partial comparison of the present results is made with an already existing methodology for the dry backfill case only, in which no presence of water has been considered on the other side of the wall. This comparison shows a good agreement with the present results. The proposed pseudostatic design factors for the case of wet backfill with the presence of water on both sides of the wall are claimed to be unique.

Forced Turbulent Convection Along Heated and Cooled Walls with Variable Fluid Properties

2021 ◽  
Author(s):  
Lorenzo Sufrà ◽  
Helfried Steiner
Keyword(s):  
Isotropic Turbulence ◽  
Turbulence Models ◽  
Turbulent Pipe Flow ◽  
Wall Friction ◽  
Effect Of Temperature ◽  
Inertial Subrange ◽  
Property Variation ◽  
Fluid Properties ◽  
Applied Approach ◽  
Heat And Momentum Transfer

Abstract The effect of temperature depending material properties on heat and momentum transfer along heated/cooled walls in turbulent pipe flow was investigated using direct numerical simulations (DNS). For the considered thermal wall conditions, always associated with a molecular Prandtl number well over unity Prw = 10, the significantly dampened/enhanced turbulent motion caused by the increase/decrease of the viscosity with distance to the heated/cooled wall, turned out to clearly dominate over the opposite trend of the enthalpy fluctuations. The Nusselt number and, quantitatively less pronounced, the wall friction coefficient are accordingly decreased/increased for the heated/cooled case. A comparison against a well established Nu-correlation unveils the limits of the generally applied approach, which is essentially based on uniform bulk flow conditions and subsequently modified accounting for material property variation, when applied to heated and cooled conditions. An enhanced disparity of the turbulent normal stresses is observed inside the inertial subrange for the heated case, indicating a stronger deviation from isotropic turbulence, which possibly challenges mostly isotropic standard turbulence models.

Investigation of the flow energy dissipation law in a centrifugal impeller in pump mode

2021 ◽  
pp. 095765092110349
Author(s):  
Ran Tao ◽  
Puxi Li ◽  
Zhifeng Yao ◽  
Ruofu Xiao
Keyword(s):  
Energy Dissipation ◽  
Flow Rate ◽  
Performance Estimation ◽  
Vortical Flow ◽  
Wall Friction ◽  
Negative Slope ◽  
Centrifugal Impeller ◽  
Pump Mode ◽  
Flow Energy ◽  
Flow Interaction

Centrifugal impeller is usually designed for water pumping. Fluid get energy from impeller but also lose energy when passing through it. To improve the efficiency and have a better operation stability, it is necessary to understand the flow energy dissipation in centrifugal impeller in pump mode. In this case, a thermodynamic analysis is conducted on a model centrifugal pump unit based on computational fluid dynamics (CFD) simulation. Typical performance curve is found with a positive-slope efficiency curve and a negative-slope head curve. With the decreasing of flow rate, both the impeller head and the flow energy dissipation (FED) will rise up. The FED is found related to the flow regime. The complex undesirable flow pattern induces high FED under off-design conditions especially at very small partial-load. Based on the visualization, FED is found with two main sources including the wall friction and the flow interaction. At over-load and design-load, the wall friction induced FED is dominant. With the decreasing of flow rate, flow interaction induced FED becomes dominant. The typical strong FED sites are found related to the striking, separation, merging and interaction of both smooth flow and vortical flow. The FED analysis will correlate the pump performance estimation and guide the design.

scholarly journals Powder flow down a vertical pipe: the effect of air flow

2002 ◽  
Vol 459 ◽  
pp. 317-345 ◽  
Author(s):  
Y. BERTHO ◽  
F. GIORGIUTTI-DAUPHINÉ ◽  
T. RAAFAT ◽  
E. J. HINCH ◽  
H. J. HERRMANN ◽  
...  
Keyword(s):  
Small Diameter ◽  
Stationary Flow ◽  
Momentum Conservation ◽  
Wall Friction ◽  
Particle Fraction ◽  
Friction Forces ◽  
Flow Rates ◽  
Lower Flow ◽  
Grain Flow ◽  
Grain Distribution

The dynamics of dry granular flows down a vertical glass pipe of small diameter have been studied experimentally. Simultaneous measurements of pressure profiles, air and grain flow rates and volume fractions of particles have been realized together with spatio-temporal diagrams of the grain distribution down the tube. At large grain flow rates, one observes a stationary flow characterized by high particle velocities, low particle fractions and a downflow of air resulting in an underpressure in the upper part of the pipe. A simple model assuming a free fall of the particles slowed down by air friction and taking into account finite particle fraction effects through Richardson–Zaki's law has been developed: it reproduces pressure and particle fraction variations with distance and estimates friction forces with the wall. At lower flow rates, sequences of high-density plugs separated by low-density bubbles moving down at a constant velocity are observed. The pressure is larger than outside the tube and its gradient reflects closely the weight of the grains. Writing mass and momentum conservation equations for the air and for the grains allows one to estimate the wall friction, which is less than 10% of the weight for grains with a clean smooth surface but up to 30% for grains with a rougher surface. At lower flow rates, oscillating-wave regimes resulting in large pressure fluctuations are observed and their frequency is predicted.

Lyon-Type Integral Forms of Wall Friction, Heat- and Mass Transfer Closure Relationships for Non-Equilibrium Two-Phase Flows: Generalization for Annular and Rod Cluster Geometries

2013 ◽  
Author(s):  
Yuri Kornienko
Keyword(s):  
Boundary Layer ◽  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Constitutive Relations ◽  
Wall Friction ◽  
Transfer Coefficients ◽  
Two Phase ◽  
Friction Heat ◽  
Integral Forms ◽  
Substance Transfer

The main goal of this paper is to describe new approach to constructing generalized closure relationships for pipe, annular and sub-channel transfer coefficients for wall friction, heat and mass transfer. The novelty of this approach is that it takes into account not only axial and transversal parameter distributions, but also an azimuthal substance transfer effects. These constitutive relations, which are primordial in the description of single- and two-phase one-dimensional (1D) flow models, can be derived from the initial 3D drift flux formulation. The approach is based on the Reynolds flow, boundary layer, and substance transfer generalized coefficient concepts. Another aim is to illustrate the validity of the “conformity principle” for the limiting cases. The method proposed in this paper is founded on the similarity theory, boundary layer model, and a phenomenological description of the regularity of the substance transfer (momentum, heat, and mass) as well as on an adequate simulation of the flow structures. With the proposed generalized approach it becomes possible to develop an integrated in form and semi-empirical in maintenance structure analytical relationships for wall friction, heat and mass transfer coefficients.

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