scholarly journals Influence of thermal gravitational-capillary convection on temperature fields in a thin wall

2021 ◽  
Vol 2119 (1) ◽  
pp. 012162
Author(s):  
N I Bodneva ◽  
V S Berdnikov ◽  
V A Grishkov ◽  
A V Mikhailov
Keyword(s):  
Free Surface ◽  
Ethyl Alcohol ◽  
Liquid Layer ◽  
Convective Flow ◽  
Vertical Wall ◽  
Temperature Gradients ◽  
Temperature Fields ◽  
Thin Wall ◽  
Vertical Walls ◽  
Thermal Films

Abstract The development of convective flow in a layer of ethyl alcohol when heating one of the vertical walls of a rectangular cavity was investigated experimentally. Thermal films were obtained, whose processing allowed plotting in time the distribution of temperature and temperature gradients on the free surface of the liquid layer and the opposite thin vertical wall of the cavity after the flow of heated liquid on it.

Three-Dimensional Natural Convective Flow in a Rectangular Enclosure With a Rectangular Heated Section on One Vertical Wall and With the Other Vertical Walls Cooled

2008 ◽  
Author(s):  
Patrick H. Oosthuizen ◽  
Abdulrahim Kalendar ◽  
Thomas M. Simko
Keyword(s):  
Convective Flow ◽  
Vertical Wall ◽  
Three Dimensional ◽  
The Other ◽  
Heated Wall ◽  
Governing Equations ◽  
Vertical Sidewall ◽  
Rectangular Enclosure ◽  
Wide Range ◽  
Vertical Walls

Three-dimensional natural convective flow in a rectangular enclosure with vertical sidewalls and horizontal top and bottom surfaces has been considered. A heated rectangular element is mounted in the middle of one vertical wall of the enclosure, the remainder of this wall being adiabatic. The remaining vertical walls are cooled to a uniform low temperature. The horizontal top and bottom walls are adiabatic. The flow has been assumed to be steady and laminar. Fluid properties have been assumed constant except for the density change with temperature that gives rise to the buoyancy forces. Radiation effects have been neglected. The numerical solution was obtained using the governing equations written in terms of dimensionless variables. The enclosure height, H′, was used as the characteristic length scale and the difference between the temperatures of the hot wall section and the cooled walls were used as the characteristic temperature scale. The dimensionless governing equations have been solved using FIDAP, a commercial software package that employs the finite element method. The solution has the following parameters: the Rayleigh number, the Prandtl number, the dimensionless height of the heated wall section compared to the overall enclosure height; the dimensionless width of the heated wall section compared to its height; the dimensionless width of the enclosure between the vertical sidewall on which the heated wall section is mounted and the opposite vertical sidewall, and the dimensionless width of the enclosure between the other two vertical sidewalls. Because of the application being considered, results have only been obtained for Pr = 0.7. Attention has been restricted to the case where the dimensionless width of the enclosure between the vertical sidewall on which the heated wall section is mounted and the opposite vertical sidewall is 0.5 and where the dimensionless width of the enclosure between the other two vertical sidewalls is 1.0. A wide range of the other parameters has been considered particular attention having been given to the effect of the dimensionless width of the heated wall section compared to its height on the mean Nusselt number for the heated wall section.

scholarly journals Laminar-turbulent transitions during thermal gravitational-capillary convection in horizontal liquid layers heated from below

2021 ◽  
Vol 2119 (1) ◽  
pp. 012166
Author(s):  
V S Berdnikov ◽  
V A Grishkov ◽  
A V Mikhailov ◽  
V O Ryabov
Keyword(s):  
Free Surface ◽  
Rayleigh Number ◽  
Ethyl Alcohol ◽  
Temperature Fields ◽  
Thermal Imager ◽  
Spatial Form ◽  
Free Surfaces

Abstract The evolution of the spatial form of the flow versus the Rayleigh number in layers with two rigid horizontal boundaries and layers with a free surface is experimentally investigated depending on the Rayleigh and Marangoni numbers. The experiments were carried out with layers of ethyl alcohol and water. A thermal imager was used to measure temperature fields on free surfaces of liquids.

Nonlinear Wave Crest Distribution on a Vertical Breakwater

2018 ◽  
Author(s):  
Valentina Laface ◽  
Giovanni Malara ◽  
Felice Arena ◽  
Ioannis A. Kougioumtzoglou ◽  
Alessandra Romolo
Keyword(s):  
Experimental Data ◽  
Free Surface ◽  
Vertical Wall ◽  
Surface Elevation ◽  
Wave Crest ◽  
Height Distribution ◽  
Free Surface Elevation ◽  
Pressure Transducers ◽  
Pressure Time ◽  
Time Histories

The paper addresses the problem of deriving the nonlinear, up to the second order, crest wave height probability distribution in front of a vertical wall under the assumption of finite spectral bandwidth, finite water depth and long-crested waves. The distribution is derived by relying on the Quasi-Deterministic representation of the free surface elevation in front of the vertical wall. The theoretical results are compared against experimental data obtained by utilizing a compressive sensing algorithm for reconstructing the free surface elevation in front of the wall. The reconstruction is pursued by starting from recorded wave pressure time histories obtained by utilizing a row of pressure transducers located at various levels. The comparison shows that there is an excellent agreement between the proposed distribution and the experimental data and confirm the deviation of the crest height distribution from the Rayleigh one.

Visualization and Prediction of Natural Convection of Water Near Its Density Maximum in a Tall Rectangular Enclosure at High Rayleigh Numbers

2000 ◽  
Vol 123 (1) ◽  
pp. 84-95 ◽  
Author(s):  
C. J. Ho ◽  
F. J. Tu
Keyword(s):  
Natural Convection ◽  
Vertical Wall ◽  
Three Dimensional ◽  
Temperature Fields ◽  
Convection Flow ◽  
Oscillatory Convection ◽  
Uniform Temperature ◽  
Density Maximum ◽  
Rectangular Enclosure ◽  
Rayleigh Numbers

An experimental and numerical investigation is presented concerning the natural convection of water near its maximum-density in a differentially heated rectangular enclosure at high Rayleigh numbers, in which an oscillatory convection regime may arise. The water in a tall enclosure of Ay=8 is initially at rest and at a uniform temperature below 4°C and then the temperature of the hot vertical wall is suddenly raised and kept at a uniform temperature above 4°C. The cold vertical wall is maintained at a constant uniform temperature equal to that of the initial temperature of the water. The top and bottom walls are insulated. Using thermally sensitive liquid crystal particles as tracers, flow and temperature fields of a temporally oscillatory convection was documented experimentally for RaW=3.454×105 with the density inversion parameter θm=0.5. The oscillatory convection features a cyclic sequence of onset at the lower quarter-height region, growth, and decay of the upward-drifting secondary vortices within counter-rotating bicellular flows in the enclosure. Two and three-dimensional numerical simulations corresponding to the visualization experiments are undertaken. Comparison of experimental with numerical results reveals that two-dimensional numerical simulation captures the main features of the observed convection flow.

scholarly journals Slit-type Breakwater; Box-type Wave Absorber

1976 ◽  
Vol 1 (15) ◽  
pp. 154 ◽  
Author(s):  
Shoshichiro Nagai ◽  
Shohachi Kakuno
Keyword(s):  
Cross Section ◽  
Water Depth ◽  
Vertical Wall ◽  
Bottom Wall ◽  
Front Wall ◽  
Type Wave ◽  
Composite Type ◽  
New Type ◽  
Vertical Walls ◽  
Horizontal Bottom

A box-type wave absorber, which is composed of a perforated vertical front-wall and a perforated, horizontal bottom-wall, has been proved by a number of experiments to show lower coefficients of reflection and more distinguished reduction of wave pressures than the perforated vertical- wall breakwater. A breakwater of composite-type, which is 1500 m long and to be built at a water depth of 10 to 11 m below the Datum Line in the Port of Osaka, is being designed to set this new type of wave absorber in the concrete caissons of the vertical-walls which is named "a slit-type breakwater". The typical cross-section of the breakwater and the advantages of the slit-type breakwater are presented herein.

scholarly journals Natural convection air flow in vertical upright-angled triangular cavities under realistic thermal boundary conditions

2016 ◽  
Vol 20 (5) ◽  
pp. 1407-1420 ◽  
Author(s):  
Jaime Sieres ◽  
Antonio Campo ◽  
José Martínez-Súarez
Keyword(s):  
Natural Convection ◽  
Vertical Wall ◽  
Aperture Angle ◽  
Temperature Fields ◽  
Uniform Heat Flux ◽  
Thermal Boundary Conditions ◽  
Nusselt Numbers ◽  
Horizontal Wall ◽  
Rayleigh Numbers

This paper presents an analytical and numerical computation of laminar natural convection in a collection of vertical upright-angled triangular cavities filled with air. The vertical wall is heated with a uniform heat flux; the inclined wall is cooled with a uniform temperature; while the upper horizontal wall is assumed thermally insulated. The defining aperture angle ? is located at the lower vertex between the vertical and inclined walls. The finite element method is implemented to perform the computational analysis of the conservation equations for three aperture angles ? (= 15?, 30? and 45?) and height-based modified Rayleigh numbers ranging from a low Ra = 0 (pure conduction) to a high 109. Numerical results are reported for the velocity and temperature fields as well as the Nusselt numbers at the heated vertical wall. The numerical computations are also focused on the determination of the value of the maximum or critical temperature along the hot vertical wall and its dependence with the modified Rayleigh number and the aperture angle.

The Effect of the Top Wall Temperature on the Laminar Natural Convection in Rectangular Cavities With Different Aspect Ratios

2009 ◽  
Vol 131 (5) ◽  
Author(s):  
Wenjiang Wu ◽  
Chan Y. Ching
Keyword(s):  
Natural Convection ◽  
Aspect Ratio ◽  
Wall Temperature ◽  
Vertical Wall ◽  
Flow Region ◽  
Temperature Profiles ◽  
Aspect Ratios ◽  
Vertical Walls ◽  
C And N ◽  
Laminar Natural Convection

The effect of the top wall temperature on the laminar natural convection in air-filled rectangular cavities driven by a temperature difference across the vertical walls was investigated for three different aspect ratios of 0.5, 1.0, and 2.0. The temperature distributions along the heated vertical wall were measured, and the flow patterns in the cavities were visualized. The experiments were performed for a global Grashof number of approximately 1.8×108 and nondimensional top wall temperatures from 0.52 (insulated) to 1.42. As the top wall was heated, the flow separated from the top wall with an undulating flow region in the corner of the cavity, which resulted in a nonuniformity in the temperature profiles in this region. The location and extent of the undulation in the flow are primarily determined by the top wall temperature and nearly independent of the aspect ratio of the cavity. The local Nusselt number was correlated with the local Rayleigh number for all three cavities in the form of Nu=C⋅Ran, but the values of the constants C and n changed with the aspect ratio.

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