Numerical simulation of argon injection into supersonic crossflow at various jet-to-freestream momentum flux ratios

2020 ◽  
Author(s):  
N. N. Fedorova ◽  
M. A. Goldfeld ◽  
S. A. Valger
Keyword(s):  
Numerical Simulation ◽  
Momentum Flux ◽  
Argon Injection

The mixing in a room by a localized finite-mass-flux source of buoyancy

2002 ◽  
Vol 471 ◽  
pp. 33-50 ◽  
Author(s):  
C. P. CAULFIELD ◽  
ANDREW W. WOODS
Keyword(s):  
Numerical Simulation ◽  
Mass Flux ◽  
Momentum Flux ◽  
Analytical Description ◽  
Return Flow ◽  
Asymptotic Model ◽  
Buoyant Plume ◽  
Finite Mass ◽  
Ambient Fluid ◽  
Source Fluid

The mixing produced by a turbulent buoyant plume with finite mass flux in a room is examined analytically and numerically. The entrainment of ambient fluid into the ascending buoyant plume leads to a return flow in the room which carries fluid downwards from the top of the room. The cycling of ambient fluid through the buoyant plume and the return flow causes the density to become uniform and gradually evolve towards that of the source fluid. As a result the buoyancy flux associated with the input fluid decreases and the plume motion becomes dominated by the source momentum flux. We develop an asymptotic model of the mixing using buoyant plume theory for a momentum-dominated flow. This provides an analytical description of the evolution of the density in the room which is in excellent accord with a full numerical simulation, and provides an improved description of the experimental filling-box data originally presented by Baines & Turner (1969).

scholarly journals NUMERICAL SIMULATION OF IRREGULAR WAVES RUNUP ON A BEACH

2018 ◽  
pp. 41
Author(s):  
Luning Sun ◽  
Andrew Kennedy ◽  
Andrew Kennedy
Keyword(s):  
Numerical Simulation ◽  
Momentum Flux ◽  
Coastal Flooding ◽  
Coastal Areas ◽  
Irregular Waves ◽  
Breaking Wave ◽  
Coastal Structures ◽  
Run Up ◽  
Wave Induced

Breaking wave induced run-up can significantly risk infrastructure in coastal areas. For instance, run-up elevation can cause coastal flooding. Moreover, the momentum flux transported onshore can also exert forces on beaches and coastal structures. This study aims at predicting shoreline forces and inundation depths via numerical simulation as well as better understanding coastal run-up events.

Direct numerical simulation of wind turbulence over breaking waves

2018 ◽  
Vol 850 ◽  
pp. 120-155 ◽  
Author(s):  
Zixuan Yang ◽  
Bing-Qing Deng ◽  
Lian Shen
Keyword(s):  
Numerical Simulation ◽  
Kinetic Energy ◽  
Wave Breaking ◽  
Momentum Flux ◽  
Breaking Waves ◽  
Wave Age ◽  
Wave Surface ◽  
Turbulence Statistics ◽  
Large Wave ◽  
Wind Turbulence

We study wind turbulence over breaking waves based on direct numerical simulation (DNS) of two-fluid flows. In the DNS, the air and water are simulated as a coherent system, with the interface captured using the coupled level-set and volume-of-fluid method. Because the wave breaking is an unsteady process, we use ensemble averaging over 100 runs to define turbulence statistics. We focus on analysing the turbulence statistics of the airflow over breaking waves. The effects of wave age and wave steepness are investigated. It is found that before wave breaking, the turbulence statistics are largely influenced by the wave age. The vertical gradient of mean streamwise velocity is positive at small and intermediate wave ages, but it becomes negative near the wave surface at large wave age as the pressure force changes from drag to thrust. Furthermore, wave-coherent motions make increasingly important contributions to the momentum flux and kinetic energy of velocity fluctuations (KE-F) as the wave age increases. During the wave breaking process, spilling breakers do not influence the wind field significantly; in contrast, plunging breakers alter the structures of wind turbulence near the wave surface drastically. It is observed from the DNS results that during wave plunging, a high pressure region occurs ahead of the wave front, which further accelerates the wind in the downstream direction. Meanwhile, a large spanwise vortex is generated, which greatly disturbs the airflow around it, resulting in large magnitudes of Reynolds stress and turbulence kinetic energy (TKE) below the wave crest. Above the crest, the magnitude of KE-F is enhanced during wave plunging at small and large wave ages, but at intermediate wave age, the transient enhancement of KE-F is absent. The effect of wave breaking on the magnitude of KE-F is further investigated through the analysis of the KE-F production. It is discovered that at small wave age, the transient enhancement of KE-F is caused by the appearance of a local maximum in the profile of total momentum flux; but at large wave age, it results from the change in the sign of the KE-F production from negative to positive, due to the sign change in the wave-coherent momentum flux. At intermediate wave age, neither of these two processes is present, and the transient growth of KE-F does not take place.

Numerical simulation study of sea spray’s effect on tropical cyclone——a case study of typhoon “Megi”

2021 ◽  
Author(s):  
Jialin Zhang ◽  
Wenqing Zhang ◽  
Haofeng Xia ◽  
Changlong Guan
Keyword(s):  
Numerical Simulation ◽  
Heat Flux ◽  
Tropical Cyclone ◽  
Latent Heat ◽  
Latent Heat Flux ◽  
Momentum Flux ◽  
Sensible Heat Flux ◽  
Sea Spray ◽  
Sensible Heat ◽  
Thermodynamic Effects

<p>Sea spray has important influence on the evolution of tropical cyclone. The influence of sea spray in the numerical simulation and prediction of tropical cyclones is not ignorable. In order to explore the kinetic and thermodynamic effects of sea spray on tropical cyclone, the drag coefficient C<sub>D </sub>and the enthalpy transfer coefficient C<sub>K</sub> with sea spray’s effects were included in the coupled ocean-atmosphere-wave-sediment transport modeling system (COAWST). The numerical results show that, the effect of sea spray can effectively improve the simulation results of tropical cyclone path. When only the kinetic effect of sea spray is considered, the momentum flux at the surface of sea is little affected, and the upward sensible heat flux and latent heat flux are slightly increased. When kinetic and thermodynamic effects of sea spray is considered at the same time, the momentum flux is slightly increased, the upward sensible heat flux is increased, and the latent heat flux is significantly increased, the intensity of tropical cyclone is significantly enhanced, mainly due to the thermodynamic effect . Considering the kinetic and thermodynamic effects of sea spray at the same time is more effective than considering the kinetic effects of sea spray in improving the intensity simulation of tropical cyclone.</p>

Wave Momentum Flux—A GARP Problem

1972 ◽  
Vol 53 (1) ◽  
pp. 17-24 ◽  
Author(s):  
D. K. Lilly
Keyword(s):  
Numerical Simulation ◽  
Large Amplitude ◽  
Momentum Flux ◽  
Large Scale ◽  
Lower Atmosphere ◽  
Forecasting Models ◽  
Lee Waves ◽  
Energy And Momentum ◽  
Large Scale Atmospheric Circulation ◽  
Wave Momentum

The energy and momentum removed from the troposphere and lower atmosphere by the breaking of large amplitude mountain lee waves may be a significant factor in the evolution and maintenance of the large-scale atmospheric circulation. A program is outlined for improving knowledge and understanding of this phenomenon and for incorporating its effects into numerical simulation and forecasting models.

Water uptake by substituted amylose tablets: experimentation and numerical simulation

2009 ◽  
Vol 00 (00) ◽  
pp. 090904073309027-8
Author(s):  
H.W. Wang ◽  
S. Kyriacos ◽  
L. Cartilier
Keyword(s):  
Numerical Simulation ◽  
Water Uptake
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