Large-Eddy Simulations of realistic atmospheric turbulence with the DLR-TAU-code initialized by in situ airborne measurements

2012 ◽  
Vol 66 ◽  
pp. 121-129 ◽  
Author(s):  
Torsten Auerswald ◽  
Jens Bange ◽  
Tobias Knopp ◽  
Keith Weinman ◽  
Rolf Radespiel
Keyword(s):  
Atmospheric Turbulence ◽  
Large Eddy Simulations ◽  
Airborne Measurements ◽  
Large Eddy

scholarly journals Airborne measurements and large-eddy simulations of small-scale gravity waves at the tropopause inversion layer over Scandinavia

2020 ◽  
Vol 20 (16) ◽  
pp. 10091-10109 ◽  
Author(s):  
Sonja Gisinger ◽  
Johannes Wagner ◽  
Benjamin Witschas
Keyword(s):  
Gravity Waves ◽  
Vertical Velocity ◽  
Inversion Layer ◽  
Large Eddy Simulations ◽  
Interfacial Waves ◽  
Airborne Measurements ◽  
Large Eddy ◽  
Wave Event ◽  
Wind Lidar

Abstract. Coordinated airborne measurements were performed by two research aircraft – Deutsches Zentrum für Luft- und Raumfahrt (DLR) Falcon and High Altitude and Long Range Aircraft (HALO) – in Scandinavia during the GW-LCYCLE II (Investigation of the life cycle of gravity waves) campaign in 2016 to investigate gravity wave processes in the upper troposphere and lower stratosphere (UTLS) region. A mountain wave event was probed over southern Scandinavia on 28 January 2016. The collected dataset constitutes a valuable combination of in situ measurements and horizontal- and altitude-resolved Doppler wind lidar and water vapour measurements with the differential absorption lidar (DIAL). In situ data at different flight altitudes and downward-pointing wind lidar measurements show pronounced changes of the horizontal scales in the vertical velocity field and of the leg-averaged momentum fluxes (MFs) in the UTLS region. The vertical velocity field was dominated by small horizontal scales with a decrease from around 20 to < 10 km in the vicinity of the tropopause inversion layer (TIL). These small scales were also found in the water vapour data and backscatter data of the DIAL. The leg-averaged MF profile determined from the wind lidar data is characterized by a pronounced kink of positive fluxes in the TIL and negative fluxes below. The largest contributions to the MF are from waves with scales > 30 km. The combination of the observations and idealized large-eddy simulations revealed the occurrence of interfacial waves having scales < 10 km on the tropopause inversion during the mountain wave event. The contribution of the interfacial waves to the leg-averaged MF is basically zero due to the phase relationship of their horizontal and vertical velocity perturbations. Interfacial waves have already been observed on boundary-layer inversions but their concept has not been applied to tropopause inversions so far. Our idealized simulations reveal that the TIL affects the vertical trend of leg-averaged MF of mountain waves and that interfacial waves can occur also on tropopause inversions. Our analyses of the horizontal- and altitude-resolved airborne observations confirm that interfacial waves actually do occur in the TIL. As predicted by linear theory, the horizontal scale of those waves is determined by the wind and stability conditions above the inversion. They are found downstream of the main mountain peaks and their MF profile varies around zero and can clearly be distinguished from the MF profile of Kelvin–Helmholtz instability. Further, the idealized large-eddy simulations reveal that the presence of the TIL is crucial in producing this kind of trapped wave at tropopause altitude.

Daytime and nighttime turbulence on Mars monitored by InSight

2020 ◽  
Author(s):  
Aymeric Spiga ◽  
Naomi Murdoch ◽  
Don Banfield ◽  
Ralph Lorenz ◽  
Claire Newman ◽  
...  
Keyword(s):  
Gravity Waves ◽  
High Frequency ◽  
Seismic Signal ◽  
Atmospheric Science ◽  
Large Eddy Simulations ◽  
Dust Devil ◽  
Large Eddy ◽  
The Many ◽  
Convective Vortices

&lt;p&gt;The InSight instrumentation for atmospheric science combines high frequency, high accuracy and continuity. This makes InSight a mission particularly suitable for studies of the variability in the Planetary Boundary Layer (PBL) of Mars -- all the more since this topic is of direct interest for quake detectability given that turbulence is the main contributor to atmosphere-induced seismic signal. For the strong daytime buoyancy-driven PBL convection, InSight significantly extends the statistics of dust-devil-like convective vortices and turbulent wind gustiness, both of which are of strong interest for aeolian science. For the moderate nighttime shear-induced PBL convection, InSight enables to explore phenomena and variability left unexplored by previous in-situ measurements on Mars. In both daytime and nighttime environments, how the gravity waves and infrasound signals discovered by InSight are being guided within the PBL is also a central topic to InSight's atmospheric investigations, with the tantalizing possibility to identify possible sources for those phenomena. InSight has been operating at the surface of Mars since 18 months, thus the seasonal evolution of the many phenomena occurring in the PBL will be an emphasis of this report. Comparisons with turbulence-resolving modeling such as Large-Eddy Simulations will be also discussed.&lt;/p&gt;

Synthetic atmospheric turbulence and wind shear in large eddy simulations of wind turbine wakes

Wind Energy ◽  
2013 ◽  
Vol 17 (8) ◽  
pp. 1247-1267 ◽  
Author(s):  
Rolf-Erik Keck ◽  
Robert Mikkelsen ◽  
Niels Troldborg ◽  
Martin de Maré ◽  
Kurt S. Hansen
Keyword(s):  
Wind Turbine ◽  
Atmospheric Turbulence ◽  
Wind Shear ◽  
Large Eddy Simulations ◽  
Large Eddy

Parameter Sensitivity and Statistical Correlation Found in Atmospheric Turbulence Studies

2020 ◽  
Author(s):  
Luis F. Rodriguez ◽  
Vinod Kumar ◽  
Arturo Rodriguez ◽  
V. M. Krushnarao Kotteda ◽  
V. S. Rao Gudimetla ◽  
...  
Keyword(s):  
Turbulent Flow ◽  
Atmospheric Turbulence ◽  
Control Volume ◽  
Large Eddy Simulations ◽  
Index Structure ◽  
Cfd Modeling ◽  
Optical Parameters ◽  
Cfd Modelling ◽  
Area Of Interest ◽  
Large Eddy

Abstract We have simulated atmospheric turbulence at several instances of possible laser propagation paths and turbulent flow regime regions within the area of interest. At a control volume that is in between two Hawaii mountains. We have applied statistical correlations between Large-Eddy Simulations results using CFD modeling and parametrizing optical variables of interest, such as refractive index structure function. By comparing our Large-Eddy Simulations with specified parameters against other Large-Eddy Simulations with almost all same parameters except for one allows us to perform a sensitivity study. To study the changes on how a parameter can affect other scenarios of Large-Eddy Simulations parametric studies. With the end goal of validating the capacity of a sensitivity analysis study using Large-Eddy Simulations versus other Large-Eddy Simulations by a way of simulating and parametrizing turbulent flow studies found in the field of CFD modeling. Allowing us to achieve our stochastic analysis by applying sensitivity studies to see how our distributions change as a function of different parameters, but one at a time. After a comparison between CFD modelling simulations we have found that after a complete parametric study, a correlation was formed between turbulent flow parameters and optical parameters of interest.

Automotive Flow and Acoustic Predictions using Large Eddy Simulations

2012 ◽  
Vol 39 (3) ◽  
pp. 272-289 ◽  
Author(s):  
Bahram Khalighi ◽  
Gianluca Iaccarino ◽  
Yaser Khalighi
Keyword(s):  
Large Eddy Simulations ◽  
Large Eddy
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