Numerical study of isotropic ocean swell

2019 ◽  
Vol 489 (5) ◽  
pp. 512-516
Author(s):  
V. V. Geogjaev ◽  
V. E. Zakharov ◽  
S. I. Badulin
Keyword(s):  
Numerical Study ◽  
Short Time ◽  
Kolmogorov Constant

A new algorithm is used for detailed numerical study of the evolution of isotropic swell in a homogeneous ocean. It is shown that the Zakharov-Filonenko spectrum occurs in an explosive manner in a short time. The Kolmogorov constant of the solution is estimated numerically.

System-Level Transient Thermal Analysis for Performance Optimization of High Power Microelectronics

2003 ◽  
Author(s):  
Victor Adrian Chiriac ◽  
Tien-Yu Tom Lee ◽  
H. S. Chen
Keyword(s):  
Thermal Performance ◽  
Performance Optimization ◽  
Numerical Study ◽  
Optimal Operation ◽  
System Level ◽  
Main Concern ◽  
Efficient Operation ◽  
Normal Test ◽  
Transient Thermal ◽  
Short Time

The increasing trend in power levels and densities leads to the need of design thermal optimization, at either module or system level. A numerical study using finite-volume software was conducted to model the transient thermal behavior of a system including a package dissipating large amounts of power over short time durations. The system is evaluated by choosing the appropriate heat sink for the efficient operation of the device under 100W of constant powering, also to enhance the thermal performance of the enclosure/box containing the test stack-up. The intent of the study is to provide a meaningful understanding and prediction of the high transient powering scenarios. The study focuses on several powering and system design scenarios, identifying the main issues encountered during a normal device operation. The power source dissipates 100W for 2 seconds then is cooled for another 2 seconds. This thermal cycle is likely to occur several times during a normal test-up, and it is the main concern of the manufacturers not to exceed a limit temperature during the device testing operation. The transient trend is further extrapolated analytically to extract the steady state peak temperature values, in order to maintain the device peak temperatures below 120°C. The benefit of the study is related to the possibility to extract the maximum/minimum temperatures for a real test involving a large number of heating-cooling cycles, yet maintaining the initial and peak temperatures within a certain range, for the optimal operation of the device. The flow and heat transfer fields are thoroughly investigated. By using a combination of numerical and analytical study, the thermal performance of the device undergoing infinity of periodic thermal cycles is further predicted.

scholarly journals Numerical study of the radio microstructure associated with the plasma turbulence emission model

1996 ◽  
Vol 160 ◽  
pp. 205-208
Author(s):  
James C. Weatherall
Keyword(s):  
Numerical Study ◽  
Modulational Instability ◽  
Plasma Turbulence ◽  
Wave Turbulence ◽  
Short Time Scale ◽  
Emission Model ◽  
Plasma Medium ◽  
Computer Solution ◽  
Emission Models ◽  
Short Time

AbstractRecent observational data of short time-scale fluctuations in the radio emission of pulsars offer the opportunity for new tests of proposed emission models. For this purpose, the existing models must be developed to make predictions regarding the temporal characteristics of the emission. A computer solution of the time evolution of plasma wave turbulence details the properties of the nonlinear plasma emission mechanism. As a consequence of ponderomotive nonlinearity in the plasma medium, two-stream growing modes develop modulational instability, leading to the onset of strong, two-dimensional plasma turbulence. The turbulence exhibits explosive spatial collapse of regions of high electric field, and the escape of bursts of radiation.

A Hybrid Rapid Microfluidic Mixer Utilizing Electrokinetic Relay and Asymmetric Flow Geometries for Lab-on-a-Chip Applications

2005 ◽  
Author(s):  
Yiou Wang ◽  
Jiang Zhe ◽  
Prashanta Dutta ◽  
Gary J. Cheng
Keyword(s):  
Dna Analysis ◽  
Numerical Study ◽  
Lab On A Chip ◽  
Chemical Agent ◽  
Asymmetric Flow ◽  
Microfluidic Mixer ◽  
Micro Total Analysis Systems ◽  
Total Analysis ◽  
Short Time ◽  
Micro Mixer

Numerical study on a rapid micromixer based on hybrid electrokinetic relay and asymmetric serpentine structures is presented. Effective mixing of liquids is essential in many applications such as drug delivery, DNA analysis/sequencing, pheromone synthesis in micro bioreactors, and biological/chemical agent detections. Rapid mixing can reduce the analysis time and permit high throughput in lab-on-a-chip or micro total analysis systems (μTAS). The proposed hybrid mixing takes advantages of both mixing enhancements induced by asymmetric flow geometries and the electrokinetic relay actuating. Simulation results show that the micro mixer is able to achieve high mixing efficiencies (94.3%) in short time (1.2s). Effects of relay frequency, electric field and channel geometry on micro-mixing have been conducted. Numerical results show that electrokinetic relay at an appropriate frequency causes effective micromixing. Moreover asymmetric flow geometries are critical for ultra effective mixing.

A Numerical Study of Underwater Explosion Bubble

2013 ◽  
Vol 706-708 ◽  
pp. 1734-1737
Author(s):  
Cho Chung Liang ◽  
Tso Liang Teng ◽  
Ching Yu Hsu ◽  
Anh Tu Nguyen
Keyword(s):  
Numerical Study ◽  
Underwater Explosion ◽  
Water Jet ◽  
Dynamical Process ◽  
Floating Structures ◽  
Jet Impact ◽  
Long Time ◽  
Bubble Pulsation ◽  
Short Time ◽  
Collapse Phase

The dynamical process of underwater explosion bubble is a very complicated phenomenon with many facets needed to consider. After detonation, shock wave propagates in a very short time while the oscillation of bubble occurs in a long time. Bubble pulsation can cause serious damage for the structures nearby due to the whipping effect, bubble pulse or water jet impact in the collapse phase. This paper presents an application of Finite Element Method (FEM), namely Eulerian technique, to simulate the dynamical process of bubble and numerical results were verified by an experiment. This approach shows it's feasibility in simulating the bubble pulsation as well as the formation of water jet at the end of first contracting circle. Although numerical model was simplified by the boundary conditions, the success of this method is foundation for further study of bubble such as in predicting the damages of both nearby submerged structures as well as floating structures.

Numerical Study on Thermal Characteristics in Fluidized Beds Using DEM-CFD

2009 ◽  
Author(s):  
Fengguo Tian ◽  
Mingchuan Zhang ◽  
Bin Wu ◽  
Dong Fu
Keyword(s):  
Fluidized Beds ◽  
Numerical Study ◽  
Three Dimensional ◽  
Thermal Characteristics ◽  
Particle Phase ◽  
Lateral Movement ◽  
Heat Transfers ◽  
Short Time ◽  
Lateral Temperature ◽  
Gas Supply

This work used a pseudo three-dimensional discrete element method (DEM) to study the way gas supply patterns affect the thermodynamics characteristics in fluidized beds. During the simulations, gas-to-particle and particle-to-particle heat transfers were considered. Results indicate that there is a lateral temperature gradient of particles in fluidized bed using horizontal air distributor incorporated with even gas supply; nevertheless, in the case of inclined air distributor together with uneven gas supply, it takes a short time for particle phase to achieve a homogenous temperature field. Hydrodynamics analysis and comparison of solid fluxes between the two cases reveal that the bubbles’ lateral movement are reduced due to even gas supply, and the particle-to-gas heat transfer is localized; however, there is an global circulating solids stream in the bed with uneven gas supply, which is thought to expand the particles’ movement range and enhance the thermal transport performance of the fluidizing system.

An experimental and numerical study for investigating the promising stratified reinforced concrete slabs

2021 ◽  
pp. 136943322110122
Author(s):  
Sameh Yehia ◽  
Tarek Aly ◽  
Osama Hassan
Keyword(s):  
Numerical Study ◽  
High Strength ◽  
Flexural Behavior ◽  
Experimental Program ◽  
Time Interval ◽  
Slab Thickness ◽  
Short Time Interval ◽  
Strength Concrete ◽  
Reinforced Concrete Slabs ◽  
Short Time

It is well known that through the structural design, the safety and economic considerations of the project represent major factors, which must be always in mind. From this point of view, the concept and idea of “Stratified Concrete” were developed. Stratified Concrete consists of two or more types of concrete; in particular, composite materials consisting of High Strength Concrete (HSC) and Normal Strength Concrete (NSC). This study showed the flexural behavior for stratified sections (HSC-NSC) by taking a short time lap (1 h) between the two mixes to get a good bond between them. An experimental program was conducted to investigate the flexural behavior of NSC (25 MPa), HSC (60 MPa), and three HSC-NSC with the effect of changing the thickness of the HSC layer of slabs (20, 40, 75 mm) that had subjected to double static loads. As well, these slabs’ experimental results were numerically verified. The most important achievement is the success of the idea of casting different strengths of concrete layers using a short time interval to improve the bending behavior of the slabs, and reach the superior thickness of the HSC layer, which represents almost a quarter of the slab thickness.

NUMERICAL STUDY OF COMPACTION OF THE EARTH DAM BODY IN THE POST-CONSTRUCTION PERIOD

2021 ◽  
pp. 66-72
Author(s):  
V.Ya. Zharnitsky ◽  
◽  
E. V. ANDREEV ◽  
Yu.V. Zaitsev
Keyword(s):  
Numerical Study ◽  
Subsequent Development ◽  
Physical And Mechanical Properties ◽  
Operational Reliability ◽  
The Body ◽  
Earth Dam ◽  
Hydraulic Structures ◽  
Construction Period ◽  
Degree Of Damage ◽  
Short Time

Ensuring the operational reliability of hydraulic structures is an important task at the stage of the life cycle of the structure. The main reasons of destructions of hydraulic structures in the course of research were identifi ed as errors in the design of such structures and their construction, or the absence of operating organizations and, as a result, the lack of proper maintenance for such structures. Such errors inevitably lead to the creation of defects in the body of hydraulic structures with the subsequent development of deformations and destruction of hydraulic structures because of a violation of the fi ltration strength. In this regard, standard methods for assessing operational reliability appear to be cumbersome and ineffi cient in the conditions of a short time allotted for assessing the degree of damage to the structure, obtaining reliable results on the current level of operational condition of hydraulic facilities, taking into account the physical and mechanical properties of the materials, the degree of damage and the characteristics of the operation.

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