scholarly journals Large-eddy simulation of laminar-turbulent transition in a swept-wing boundary layer

1997 ◽  
Author(s):  
Xiaoli Huai ◽  
Ugo Piomelli ◽  
Ronald Joslin ◽  
Xiaoli Huai ◽  
Ugo Piomelli ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Large Eddy Simulation ◽  
Swept Wing ◽  
Eddy Simulation ◽  
Turbulent Transition ◽  
Large Eddy ◽  
Laminar Turbulent Transition

Constrained large-eddy simulation of laminar-turbulent transition in channel flow

2014 ◽  
Vol 26 (9) ◽  
pp. 095103 ◽  
Author(s):  
Yaomin Zhao ◽  
Zhenhua Xia ◽  
Yipeng Shi ◽  
Zuoli Xiao ◽  
Shiyi Chen
Keyword(s):  
Large Eddy Simulation ◽  
Channel Flow ◽  
Eddy Simulation ◽  
Turbulent Transition ◽  
Large Eddy ◽  
Laminar Turbulent Transition

scholarly journals OCORRÊNCIA DE INTERMITÊNCIA NA TRANSIÇÃO LAMINAR-TURBULENTA EM UM ESCOAMENTO DE COUETTE PLANO

2016 ◽  
Vol 38 ◽  
pp. 354
Author(s):  
Jean Jonathan Schuster ◽  
Cristiano Henrique Schuster ◽  
Eduardo Stüker ◽  
Áttila Leães Rodrigues ◽  
Luiz Eduardo Medeiros ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Transition Flow ◽  
Large Eddy Simulation Model ◽  
Eddy Simulation ◽  
Turbulent Transition ◽  
Long Wave ◽  
Turbulent Flow Regime ◽  
Large Eddy ◽  
Almost All ◽  
Laminar Turbulent Transition

The transition from laminar-turbulent flow regime is important in most of the fluid mechanics application areas. In the planetary boundary layer (PBL), the flow is predominantly turbulent. However, shortly after sunset, the incidence of solar radiation ceases and the surface begins to lose heat through the emission of long-wave, yielding in a thermical stratified stable boundary layer (SBL), where turbulence can be suppressed in almost all scales. Under these conditions the production of turbulence is predominantly mechanical, and at nights with strong stratification, the turbulent activity is reduced by several orders of magnitude and can rise abruptly in unpredictable ways, giving origin to a phenomenon known as global intermittency. The globla intermittency is a phenomenon that occurs in the transition flow in the PBL, similarly to intermittency which occurs in the laminar-turbulent transition. Thus, this work aims to develop a numerical experiment to reproduce the laminar-turbulent transition in a thermally stratified Couette flow, using a large eddy simulation model. The simulations show that for a certain range of parameters during the transition laminar-turbulent, turbulence appeared intermittently in the flow.

scholarly journals Nocturnal Boundary Layer Erosion Analysis in the Amazon Using Large-Eddy Simulation during GoAmazon Project 2014/5

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 240
Author(s):  
Rayonil Carneiro ◽  
Gilberto Fisch ◽  
Theomar Neves ◽  
Rosa Santos ◽  
Carlos Santos ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Large Eddy Simulation ◽  
Rainy Season ◽  
Nocturnal Boundary Layer ◽  
Enso Event ◽  
Dry Season ◽  
Dry Period ◽  
Additional Energy ◽  
Eddy Simulation ◽  
Large Eddy

This study investigated the erosion of the nocturnal boundary layer (NBL) over the central Amazon using a high-resolution model of large-eddy simulation (LES) named PArallel Les Model (PALM) and observational data from Green Ocean Amazon (GoAmazon) project 2014/5. This data set was collected during four intense observation periods (IOPs) in the dry and rainy seasons in the years 2014 (considered a typical year) and 2015, during which an El Niño–Southern Oscillation (ENSO) event predominated and provoked an intense dry season. The outputs from the PALM simulations represented reasonably well the NBL erosion, and the results showed that it has different characteristics between the seasons. During the rainy season, the IOPs exhibited slow surface heating and less intense convection, which resulted in a longer erosion period, typically about 3 h after sunrise (that occurs at 06:00 local time). In contrast, dry IOPs showed more intensive surface warming with stronger convection, resulting in faster NBL erosion, about 2 h after sunrise. A conceptual model was derived to investigate the complete erosion during sunrise hours when there is a very shallow mixed layer formed close to the surface and a stable layer above. The kinematic heat flux for heating this layer during the erosion period showed that for the rainy season, the energy emitted from the surface and the entrainment was not enough to fully heat the NBL layer and erode it. Approximately 30% of additional energy was used in the system, which could come from the release of energy from biomass. The dry period of 2014 showed stronger heating, but it was also not enough, requiring approximately 6% of additional energy. However, for the 2015 dry period, which was under the influence of the ENSO event, it was shown that the released surface fluxes were sufficient to fully heat the layer. The erosion time of the NBL probably influenced the development of the convective boundary layer (CBL), wherein greater vertical development was observed in the dry season IOPs (~1500 m), while the rainy season IOPs had a shallower layer (~1200 m).

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