A comparative study of treatment of two-dimensional two-phase flows of steam by a Runge-Kutta and by Denton's methods

2007 ◽  
Vol 221 (6) ◽  
pp. 689-706 ◽  
Author(s):  
F Bakhtar ◽  
M Y Zamri ◽  
J M Rodriguez-Lelis
Keyword(s):  
Comparative Study ◽  
Excellent Agreement ◽  
Experimental Results ◽  
Experimental Measurements ◽  
Two Dimensional ◽  
Oscillating Flows ◽  
Two Phase ◽  
Time Marching ◽  
Runge Kutta ◽  
Refined Grid

This paper describes a comparative study of the treatment of two-dimensional nucleating flows of steam using two different time-marching numerical schemes. A treatment based on Denton's scheme but a refined grid has been available from earlier work. To compare with this a treatment based on the Runge-Kutta scheme has been developed, which is described. Solutions using this scheme and a simple mesh are compared with experimental results and with solutions using the earlier treatment. The agreement obtained between the two schemes and with the experimental results is satisfactory. Oscillating flows in a convergent-divergent nozzle are also examined and excellent agreement obtained with experimental measurements.

A Model for Cw Laser Recrystallization Including Reflectivity Effects

1983 ◽  
Vol 23 ◽  
Author(s):  
I.D. Calder
Keyword(s):  
Excellent Agreement ◽  
Solid Phase ◽  
Phase Region ◽  
Experimental Results ◽  
Two Phase ◽  
Cw Laser ◽  
Laser Recrystallization ◽  
Outer Annulus ◽  
Analytic Expressions ◽  
Practical Model

ABSTRACTA simple, practical model is developed for cw laser recrystallization of silicon and SOI structures, taking into account spatial variations in optical reflectivity. The power absorption is assumed to be uniform within each of three regions: the central molten spot, the annular two-phase region, and an outer annulus to account for absorption in the solid phase. Analytic expressions are obtained for the radial and depth dependence of the temperature, for the melt depth, the melt radius, the melt threshold, the crystallization threshold and the substrate melt threshold. SOI structures are considered and comparison with some experimental results shows excellent agreement.

The effects of surface tension and tube inclination on a two-dimensional rising bubble

1987 ◽  
Vol 184 ◽  
pp. 1-14 ◽  
Author(s):  
Benoit Couët ◽  
Gary S. Strumolo
Keyword(s):  
Surface Tension ◽  
Froude Number ◽  
Excellent Agreement ◽  
Experimental Results ◽  
Large Bubble ◽  
Continuous Derivative ◽  
Two Dimensional ◽  
Rising Bubble ◽  
Theoretical Predictions ◽  
Bubble Rising

The effects of surface tension σ and tube inclination β on the Froude number Fr of a large bubble rising in a two-dimensional duct is considered. It is found that there exists either one (for small σ and β > 0°) or a set (for any σ and β = 0°) of Fr-values for which the bubble has a continuous derivative at the nose. By selecting either this single Fr (or the maximum of the set), we obtain solutions in excellent agreement with both theoretical predictions and experimental results.

The Effect of Surface Roughness on the Head-Tape Interface

1996 ◽  
Vol 118 (2) ◽  
pp. 376-381 ◽  
Author(s):  
Y. Wu ◽  
F. E. Talke
Keyword(s):  
Surface Roughness ◽  
Contact Pressure ◽  
Excellent Agreement ◽  
Experimental Results ◽  
Numerical Calculations ◽  
Experimental Measurements ◽  
Parabolic Model ◽  
Recording Density ◽  
Curve Fit ◽  
Effect Of Surface

The effect of tape surface roughness on the head-tape interface is investigated for typical head contours using tapes with different surface roughness characteristics. Intensity-based monochromatic interferometry is used to obtain the asperity compliance curves for tapes of different roughness by relating contact pressure to the spacing between the head and the tape. A parabolic model and the Greenwood-Williamson model for contact between rough surfaces are used to “curve fit” experimental results for contact pressure versus spacing, and numerical calculations for the head-tape spacing of a cylindrical head with and without transverse slots are presented for two tapes with different roughness characteristics. The numerical calculations for the head-tape spacing are compared with experimental measurements showing excellent agreement between numerical and experimental results. It is concluded that the head-tape spacing for high recording density applications is limited by tape surface roughness.

Comparative Study Between Geant4, MCNP6 and Experimental Results Against Gamma Radiation Comes from a Cobalt-60 Source

2020 ◽  
Vol 75 (5) ◽  
pp. 507-511
Author(s):  
Y. El-Ouardi ◽  
A. Dadouch ◽  
A. Aknouch ◽  
M. Mouhib ◽  
A. Maghnouj ◽  
...  
Keyword(s):  
Comparative Study ◽  
Gamma Radiation ◽  
Experimental Results

Features of spatial shock-wave flows in vapor-gas-liquid mixtures

2014 ◽  
Vol 10 ◽  
pp. 27-31
Author(s):  
R.Kh. Bolotnova ◽  
U.O. Agisheva ◽  
V.A. Buzina
Keyword(s):  
Shock Wave ◽  
High Pressure ◽  
Shock Waves ◽  
Liquid Mixture ◽  
Liquid Mixtures ◽  
Pressure Vessels ◽  
Water Mixture ◽  
Two Dimensional ◽  
Nonstationary Processes ◽  
Two Phase

The two-phase model of vapor-gas-liquid medium in axisymmetric two-dimensional formulation, taking into account vaporization is constructed. The nonstationary processes of boiling vapor-water mixture outflow from high-pressure vessels as a result of depressurization are studied. The problems of shock waves action on filled by gas-liquid mixture volumes are solved.

Investigation of two-dimensional nonstationary processes of outflow a gas-saturated liquid from axisymmetric vessels

2012 ◽  
Vol 9 (1) ◽  
pp. 47-52
Author(s):  
R.Kh. Bolotnova ◽  
V.A. Buzina
Keyword(s):  
Comparative Analysis ◽  
Numerical Model ◽  
Liquid Mixture ◽  
Phase Model ◽  
Test Problems ◽  
Two Dimensional ◽  
Nonstationary Processes ◽  
Saturated Liquid ◽  
Two Phase ◽  
One Dimensional

The two-dimensional and two-phase model of the gas-liquid mixture is constructed. The validity of numerical model realization is justified by using a comparative analysis of test problems solution with one-dimensional calculations. The regularities of gas-saturated liquid outflow from axisymmetric vessels for different geometries are established.

scholarly journals Is contact angle a cause or an effect? – A cautionary tale

2020 ◽  
Vol 146 ◽  
pp. 03004
Author(s):  
Douglas Ruth
Keyword(s):  
Contact Angle ◽  
Solid Surface ◽  
Contact Angles ◽  
Two Dimensions ◽  
Experimental Results ◽  
Flow In Porous Media ◽  
Two Dimensional ◽  
Wide Range ◽  
Fluid Drop ◽  
Surrounding Fluid

The most influential parameter on the behavior of two-component flow in porous media is “wettability”. When wettability is being characterized, the most frequently used parameter is the “contact angle”. When a fluid-drop is placed on a solid surface, in the presence of a second, surrounding fluid, the fluid-fluid surface contacts the solid-surface at an angle that is typically measured through the fluid-drop. If this angle is less than 90°, the fluid in the drop is said to “wet” the surface. If this angle is greater than 90°, the surrounding fluid is said to “wet” the surface. This definition is universally accepted and appears to be scientifically justifiable, at least for a static situation where the solid surface is horizontal. Recently, this concept has been extended to characterize wettability in non-static situations using high-resolution, two-dimensional digital images of multi-component systems. Using simple thought experiments and published experimental results, many of them decades old, it will be demonstrated that contact angles are not primary parameters – their values depend on many other parameters. Using these arguments, it will be demonstrated that contact angles are not the cause of wettability behavior but the effect of wettability behavior and other parameters. The result of this is that the contact angle cannot be used as a primary indicator of wettability except in very restricted situations. Furthermore, it will be demonstrated that even for the simple case of a capillary interface in a vertical tube, attempting to use simply a two-dimensional image to determine the contact angle can result in a wide range of measured values. This observation is consistent with some published experimental results. It follows that contact angles measured in two-dimensions cannot be trusted to provide accurate values and these values should not be used to characterize the wettability of the system.

scholarly journals Modeling Transient Flows in Heterogeneous Layered Porous Media Using the Space–Time Trefftz Method

2021 ◽  
Vol 11 (8) ◽  
pp. 3421
Author(s):  
Cheng-Yu Ku ◽  
Li-Dan Hong ◽  
Chih-Yu Liu ◽  
Jing-En Xiao ◽  
Wei-Po Huang
Keyword(s):  
Porous Media ◽  
Time Domain ◽  
Numerical Solutions ◽  
Space Time ◽  
Two Dimensional ◽  
Transient Flows ◽  
Layered Porous Media ◽  
Time Marching ◽  
Time Basis ◽  
Marching Scheme

In this study, we developed a novel boundary-type meshless approach for dealing with two-dimensional transient flows in heterogeneous layered porous media. The novelty of the proposed method is that we derived the Trefftz space–time basis function for the two-dimensional diffusion equation in layered porous media in the space–time domain. The continuity conditions at the interface of the subdomains were satisfied in terms of the domain decomposition method. Numerical solutions were approximated based on the superposition principle utilizing the space–time basis functions of the governing equation. Using the space–time collocation scheme, the numerical solutions of the problem were solved with boundary and initial data assigned on the space–time boundaries, which combined spatial and temporal discretizations in the space–time manifold. Accordingly, the transient flows through the heterogeneous layered porous media in the space–time domain could be solved without using a time-marching scheme. Numerical examples and a convergence analysis were carried out to validate the accuracy and the stability of the method. The results illustrate that an excellent agreement with the analytical solution was obtained. Additionally, the proposed method was relatively simple because we only needed to deal with the boundary data, even for the problems in the heterogeneous layered porous media. Finally, when compared with the conventional time-marching scheme, highly accurate solutions were obtained and the error accumulation from the time-marching scheme was avoided.

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