Study of Interaction Patterns Between Evolving Interfaces Due to Boiling Around Different Arrangements of Heated Cylinders

2019 ◽  
Vol 141 (11) ◽  
Author(s):  
M. B. Darshan ◽  
Ravi Kumar ◽  
Arup Kumar Das
Keyword(s):  
Interaction Coefficient ◽  
Thickness Variation ◽  
Base Case ◽  
Vapor Film ◽  
Interaction Patterns ◽  
Vapor Growth ◽  
Horizontal Shift ◽  
Particle Hydrodynamics ◽  
Staggered Arrangement ◽  
Domain Discretization

Abstract An effort has been made to numerically study the interactions between the vapor films generating from multiple heated cylinders placed in a saturated water pool with a view to understand the influence of neighboring interface on growth of vapor films. Lagrangian smoothed particle hydrodynamics (SPH) has been used for domain discretization and interface reconstruction. Unconstrained growth of vapor film around a cylinder is simulated first and the nature of vapor dynamics has been taken as a base case for the study of interaction patterns. Vapor growth has been understood through temporal phase contours, azimuthal thickness variation, and trajectory of the centroid of the vapor mass. It has been shown that the presence of cylinder in vertical neighborhood results in suppression of vapor film generating from the bottom cylinder, whereas, the vapor films generating from two cylinders placed in horizontal neighborhood experience a horizontal shift. Studies have also been made to observe multidirectional interactions of vapor films with heated cylinders placed in an inline array, vertically staggered and horizontally staggered arrangements. It has been found that the highest deviation from unconstrained growth occurs in case of the center cylinder in a horizontally staggered arrangement as compared to others. Mutual interaction coefficient and indices are proposed to judge the best possible arrangement in case of a requirement for placement of stacked cylinders.

scholarly journals APPLICATION OF SMOOTHED PARTICLE HYDRODYNAMICS IN EVALUATING THE PERFORMANCE OF COASTAL RETROFIT STRUCTURES

2018 ◽  
pp. 109 ◽  
Author(s):  
Soroush Abolfathi ◽  
Dong Shudi ◽  
Sina Borzooei ◽  
Abbas Yeganeh-Bakhtiari ◽  
Jonathan Pearson
Keyword(s):  
Numerical Model ◽  
Smoothed Particle Hydrodynamics ◽  
Vertical Wall ◽  
Laboratory Data ◽  
Wave Structure ◽  
Base Case ◽  
Submerged Breakwater ◽  
Wave Overtopping ◽  
Particle Hydrodynamics ◽  
Smoothed Particle

This study develops an accurate numerical tool for investigating optimal retrofit configurations in order to minimize wave overtopping from a vertical seawall due to extreme climatic events and under changing climate. A weakly compressible smoothed particle hydrodynamics (WCSPH) model is developed to simulate the wave-structure interactions for coastal retrofit structures in front of a vertical seawall. A range of possible physical configurations of coastal retrofits including re-curve wall and submerged breakwater are modelled with the numerical model to understand their performance under different wave and structural conditions. The numerical model is successfully validated against laboratory data collected in 2D wave flume at Warwick Water Laboratory. The findings of numerical modelling are in good agreement with the laboratory data. The results indicate that recurve wall is more effective in mitigating wave overtopping and provides more resilience to coastal flooding in comparison to base-case (plain vertical wall) and submerged breakwater retrofit.

scholarly journals APPLICATION OF SMOOTHED PARTICLE HYDRODYNAMICS IN EVALUATING THE PERFORMANCE OF COASTAL RETROFIT STRUCTURES

2018 ◽  
Vol 1 (36) ◽  
pp. 109 ◽  
Author(s):  
Soroush Abolfathi ◽  
Dong Shudi ◽  
Sina Borzooei ◽  
Abbas Yeganeh-Bakhtiari ◽  
Jonathan Pearson
Keyword(s):  
Numerical Model ◽  
Smoothed Particle Hydrodynamics ◽  
Vertical Wall ◽  
Laboratory Data ◽  
Wave Structure ◽  
Base Case ◽  
Submerged Breakwater ◽  
Wave Overtopping ◽  
Particle Hydrodynamics ◽  
Smoothed Particle

This study develops an accurate numerical tool for investigating optimal retrofit configurations in order to minimize wave overtopping from a vertical seawall due to extreme climatic events and under changing climate. A weakly compressible smoothed particle hydrodynamics (WCSPH) model is developed to simulate the wave-structure interactions for coastal retrofit structures in front of a vertical seawall. A range of possible physical configurations of coastal retrofits including re-curve wall and submerged breakwater are modelled with the numerical model to understand their performance under different wave and structural conditions. The numerical model is successfully validated against laboratory data collected in 2D wave flume at Warwick Water Laboratory. The findings of numerical modelling are in good agreement with the laboratory data. The results indicate that recurve wall is more effective in mitigating wave overtopping and provides more resilience to coastal flooding in comparison to base-case (plain vertical wall) and submerged breakwater retrofit.

Experimental Investigation of Air Flow Through a Perforated Tile in a Raised Floor Data Center

2015 ◽  
Vol 137 (1) ◽  
Author(s):  
Vaibhav K. Arghode ◽  
Yogendra Joshi
Keyword(s):  
Flow Field ◽  
Flow Rate ◽  
Air Flow ◽  
Base Case ◽  
Flow Rates ◽  
Cold Air ◽  
Air Jet ◽  
Image Velocimetry ◽  
Flow Features ◽  
Staggered Arrangement

Raised floor data centers supply cold air from a pressurized plenum to the server racks through perforated floor tiles. Hence, the design of an efficient air delivery scheme requires better understanding of the flow features, through and above the perforated tiles. Different tiles with circular pores in a staggered arrangement and with the same thickness are considered. Tile sheet porosities of 23% and 40%, air flow rates of 0.56 m3/s (1177 CFM) and 0.83 m3/s (1766 CFM), and pore sizes of 3.18 mm (1/8 in.) and 6.35 mm (1/4 in.) are investigated. Tiles with 38.1 mm (1.5 in.) region blocked along the edges is compared to the base case with 12.7 mm (0.5 in.) blocked edges. Width reduced to 0.46 m (1.5 ft) from standard width of 0.61 m (2 ft) is also examined. Reduced tile width is used to simulate 0.91 m (3 ft) cold aisle instead of standard 1.22 m (4 ft) cold aisle, with potential to save floor space. A case where the rack is recessed by 76.2 mm (3 in.) from the tile edge is also included in the investigation, as there is a possibility of having racks nonadjacent to the tile edges. Particle image velocimetry (PIV) technique is used to characterize the flow field emerging from a perforated tile and entering the adjacent rack. Experiments suggest that lower tile porosity significantly increases cold air bypass from the top, possibly due to higher air jet momentum above the tile, as compared to a tile with higher porosity. For the air flow rates investigated here, the flow field was nearly identical and influence of flow rate was nondistinguishable. The influence of pore size was non-negligible, even when the porosity and flow rate for the two cases were same. Larger blockage of the tile edges resulted in higher cold air bypass from the top. Reduction in the tile width showed improved air delivery to the rack with considerably reduced cold air bypass. Recessing the rack did not affect the flow field significantly.

Multi-Phase Gearbox Modelling Using GPU-Accelerated Smoothed Particle Hydrodynamics Method

2019 ◽  
Author(s):  
Muraleekrishnan Menon ◽  
Kamil Szewc ◽  
Vishal Maurya
Keyword(s):  
Smoothed Particle Hydrodynamics ◽  
Single Phase ◽  
Free Surface Flows ◽  
Base Case ◽  
Multiphase Model ◽  
Engineering Applications ◽  
Promising Alternative ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Lubricant Distribution

Abstract Developments in automotive design such as electrification of engines and a growing need to improve driveline efficiency requires adaption of old techniques. The ability to make fast and accurate Computational Fluid Dynamics (CFD) assessment is of high importance to the development of novel powertrains. Consequently, innovative numerical techniques and continuous improvements to existing CFD codes is relevant to ensure reliability. This work extends the capabilities of a Smoothed Particle Hydrodynamics (SPH) code to include multiphase modeling, studied using a gearbox model. A vast majority of CFD codes use grid-based approaches following the Eulerian spatial discretization, which is quite established in engineering applications. Lagrangian based approaches where the moving fluid particles are discretized over time and space present a promising alternative. One of the most common methods of this kind is the Smoothed Particle Hydrodynamics (SPH) method, a fully Lagrangian, particle-based approach for fluid-flow simulations. The main advantage is the absence of numerical grid for computations, which eliminates complexities of interface handling. Nowadays, the SPH approach is more commonly used for hydro-engineering applications involving free-surface flows. New techniques to perform numerical simulations on Graphics Processing Units (GPU) virtually eliminates some of the disadvantages of the method. In this work, we present our multi-GPU solution designed for both GPU-equipped desktops and multi-GPU supercomputers. Fluid dynamic simulations on a single gearbox model is used to validate the multiphase model, by comparing the results with earlier simulations that use a single-phase model omitting air-lubricant interface in the gearbox. The base case in the study is a single bevel gear placed inside a cuboid case with a lubricant depth equivalent to 25% gear diameter. Simulations are performed at various rotational speeds, and corresponding lubricant distribution and churning losses are obtained. The current study targets a comparison of the single-phase and multiphase models in approximating the lubricant distribution and churning loss values at nominal rotational speeds. This serves to standardize the numerical procedure, which will help in improving the accuracy of churning loss calculations through validations against experimental results in the future.

Some Quantification Problems in Parallel EELS Images

1990 ◽  
Vol 48 (2) ◽  
pp. 36-37
Author(s):  
G. Botton ◽  
G. L’Espérance ◽  
M.D. Ball ◽  
C.E. Gallerneault
Keyword(s):  
Electron Microscope ◽  
Imaging System ◽  
Signal To Noise Ratio ◽  
Scanning Transmission Electron Microscope ◽  
Acquisition Time ◽  
Thickness Variation ◽  
Transmission Electron ◽  
Distribution Of Elements ◽  
Scanning Transmission ◽  
Present Distribution

The recently developed parallel electron energy loss spectrometers (PEELS) have led to a significant reduction in spectrum acquisition time making EELS more useful in many applications in material science. Dwell times as short as 50 msec per spectrum with a PEELS coupled to a scanning transmission electron microscope (STEM), can make quantitative EEL images accessible. These images would present distribution of elements with the high spatial resolution inherent to EELS. The aim of this paper is to briefly investigate the effect of acquisition time per pixel on the signal to noise ratio (SNR), the effect of thickness variation and crystallography and finally the energy stability of spectra when acquired in the scanning mode during long periods of time.The configuration of the imaging system is the following: a Gatan PEELS is coupled to a CM30 (TEM/STEM) electron microscope, the control of the spectrometer and microscope is performed through a LINK AN10-85S MCA which is interfaced to a IBM RT 125 (running under AIX) via a DR11W line.

Relationships between body image boundary and interaction patterns on the MAPS test.

1968 ◽  
Vol 32 (5, Pt.1) ◽  
pp. 575-578 ◽  
Author(s):  
Martha C. Frede ◽  
Donald B. Gautney ◽  
James C. Baxter
Keyword(s):  
Body Image ◽  
Interaction Patterns

Simulation de l'écoulement au cours du procédé de rotomoulage par la méthode Smoothed Particle Hydrodynamics (SPH)

2008 ◽  
Vol 96 (6) ◽  
pp. 263-268 ◽  
Author(s):  
E. Mounif ◽  
V. Bellenger ◽  
A. Ammar ◽  
R. Ata ◽  
P. Mazabraud ◽  
...  
Keyword(s):  
Smoothed Particle Hydrodynamics ◽  
Particle Hydrodynamics ◽  
Smoothed Particle
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