A5002681944- Fluid Dynamics and Turbulent Flows
- Meteorological Phenomena and Simulations
- Ionosphere and magnetosphere dynamics
- Wind and Air Flow Studies
- Computational Fluid Dynamics and Aerodynamics
- Fluid Dynamics and Vibration Analysis
- Solar and Space Plasma Dynamics
- Planetary Science and Exploration
- Seismic Waves and Analysis
- Geophysics and Gravity Measurements
- Space exploration and regulation
- Tropical and Extratropical Cyclones Research
- Atmospheric aerosols and clouds
- Ocean Waves and Remote Sensing
- Aerodynamics and Acoustics in Jet Flows
- Atmospheric Ozone and Climate
- Refrigeration and Air Conditioning Technologies
- Astro and Planetary Science
- Geomagnetism and Paleomagnetism Studies
- Gas Dynamics and Kinetic Theory
- Turbomachinery Performance and Optimization
- Atmospheric and Environmental Gas Dynamics
- Space Science and Extraterrestrial Life
- Spacecraft Design and Technology
- Oceanographic and Atmospheric Processes
G & A Technical Software (United States)
2019-2024
University of California, San Diego
2023
University of San Diego
2023
Embry–Riddle Aeronautical University
2023
University of Colorado Boulder
2022
Northwest Research Associates
2004-2017
Montana State University
2017
University of Colorado System
2004-2005
The University of Texas at Arlington
2000-2005
The University of Texas at Austin
2005
A method for generating three-dimensional, time-dependent turbulent inflow data simulations of complex spatially developing boundary layers is described. The approach to extract instantaneous planes velocity from an auxiliary simulation a zero pressure gradient layer. also developing, but generates its own conditions through sequence operations where the field at downstream station rescaled and re-introduced inlet. This procedure essentially variant Spalart method, optimized so that existing...
The dynamic model for large-eddy simulation of turbulence samples information from the resolved velocity field in order to optimize subgrid-scale coefficients. When method is used conjunction with Smagorinsky eddy-viscosity model, and sampling process formulated a spatially local fashion, resulting coefficient highly variable contains significant fraction negative values. Negative eddy viscosity leads computational instability as result always augmented stabilization mechanism. In most...
Conservation properties of the mass, momentum, and kinetic energy equations for incompressible flow are specified as analytical requirements a proper set discrete equations. Existing finite difference schemes in regular staggered grid systems checked violations conservation few important discrepancies pointed out. In particular, it is found that none existing higher order mesh system simultaneously conserve energy. This deficiency corrected through derivation general family fully...
In a previous paper, Germano, et al. (1991) proposed method for computing coefficients of subgrid-scale eddy viscosity models as function space and time. This procedure has the distinct advantage being self-calibrating requires no priori specification model or use wall damping functions. However, original formulation contained some mathematical inconsistencies that limited utility model. particular, applicability was restricted to flows are statistically homogeneous in at least one...
A class of filters for large eddy simulations turbulent inhomogeneous flows is presented. general set rules constructing discrete in complex geometry given and examples such are With these the commutation error between numerical differentiation filtering can be made arbitrarily small, allowing derivation a consistent equations scale field. The application explicit issue boundary conditions filtered field also discussed.
Large-eddy simulation (LES) has been used to study the flow in a planar asymmetric diffuser. The wide range of spatial and temporal scales, presence an adverse pressure gradient, formation unsteady separation bubble rear part diffuser make this challenging test case for assessing predictive capability LES. Simulation results mean flow, recovery skin friction are excellent agreement with data from two recent experiments. inflow consists fully developed turbulent channel at Reynolds number...
Probability density functions (PDFs) of the strain-rate tensor eigenvalues are examined. It is found that accepted normalization used to bound intermediate eigenvalue between ±1 leads a PDF must vanish at end points for non-singular distribution strain states. This purely kinematic constraint has led previous investigators conclude incorrectly locally axisymmetric deformations do not exist in turbulent flows. An alternative presented does bias probability near limits. shown lead expected...
Abstract An anelastic numerical model is used to explore the dynamics accompanying attainment of large amplitudes by gravity waves (GWs) that are localized in altitude and time. GW momentum transport induces mean flow variations a packet grows exponentially with altitude, significant phase speed, phase, across packet. These arise because occupies region undergoing accelerations, induced speed referred as “self‐acceleration.” Results presented here reveal self‐acceleration time ultimately...
Abstract Fritts, Wang, Lund, and Thorpe (2022, https://doi.org/10.1017/jfm.2021.1085 ) Thorpe, Lund https://doi.org/10.1017/jfm.2021.1086 described a 3‐dimensional direct numerical simulation of interacting Kelvin‐Helmholtz instability (KHI) billows resulting tube knot (T&K) dynamics that arise at stratified shear layer defined by an idealized, large‐amplitude inertia‐gravity wave. Using similar initial conditions, we performed high‐resolution compressible to explore the emission GWs...
The standard dynamic procedure is based on the scale-invariance assumption that model coefficient C same at grid and test-filter levels. In many applications this condition not met. We consider case when filter-length, Δ, approaches Kolmogorov scale, η, C(Δ→η)→0̇. Using filtered direct numerical simulation data, we show yields corresponding to scale (αΔ) instead of (Δ). Several account for dependence in Smagorinsky are considered, most robust these tested large eddy forced isotropic...
Numerical simulations are used to study gravity wave (GW) propagation, instability, and breaking in the lower thermosphere. Compressible effects accounted for via an anelastic formulation of equations motion we employ a realistic description background thermodynamic state. An initially low‐amplitude, monochromatic GW with horizontal wavelength 60 km intrinsic frequency N /3.7 is introduced at boundary allowed propagate higher altitudes. The steepens as it propagates upward displays...
Abstract Results of two‐dimensional and narrow three‐dimensional (2‐D 2.5‐D) simulations a gravity wave (GW) packet localized in altitude along its propagation direction employing new, versatile compressible model are described. The explore self‐acceleration instability dynamics an idealized atmosphere at rest under mean solar conditions domain extending to 260 km 1,800 horizontally without artificial dissipation. High resolution the central 2.5‐D enables description 3‐D accounting for...
Dong et al. (2020, https://doi.org/10.1029/2019JD030691) employed a new compressible model to examine gravity wave (GW) self-acceleration dynamics, instabilities, secondary (SGW) generation, and mean forcing for GW packets localized in two dimensions (2D). This paper extends the exploration of dynamics packet three (3D) propagating into tidal winds mesosphere thermosphere. As 2D responses, 3D are found be significant include phase distortions, stalled vertical propagation, local SGW acoustic...
Abstract A gravity wave (GW) model that includes influences of temperature variations and large‐scale advection on polar mesospheric cloud (PMC) brightness having variable dependence particle radius is developed. This Complex Geometry Compressible Atmosphere Model for PMCs (CGCAM‐PMC) described applied here three‐dimensional (3‐D) GW packets undergoing self‐acceleration (SA) dynamics, breaking, momentum deposition, secondary (SGW) generation below at PMC altitudes. Results reveal exhibiting...
We perform a direct numerical simulation (DNS) of interacting Kelvin–Helmholtz instabilities (KHI) that arise at stratified shear layer where KH billow cores are misaligned or exhibit varying phases along their axes. Significant evidence these dynamics in early laboratory shear-flow studies by Thorpe ( Geophys. Astrophys. Fluid Dyn. , vol. 34, 1985, pp. 175–199) and J. Res. 92, 1987, 5231–5248), observations misalignments tropospheric clouds (Thorpe, Q. R. Meteorol. Soc. 128, 2002,...
Dynamic models for large eddy simulation of the G-equation turbulent premixed combustion are proposed and tested in forced homogeneous isotropic turbulence. The basic idea is to represent “filtered propagation term” as “propagation filtered front at higher speed,” where enhanced filtered-front speed modeled. validity linear relation between flame turbulence intensity examined through use direct numerical (DNS) data. These tests show a range scalings from cubic depending on ratio well filter...
Direct numerical simulation (DNS) of a time-developing turbulent wake evolving in stably stratified background is presented. A large initial Froude number chosen to allow the become fully and axisymmetric before stratification affects spreading rate mean defect. Turbulence statistics are formed by averaging over homogeneous streamwise direction domain that larger than earlier stratified-wake simulations order reduce statistical uncertainty. The DNS results used cast light on mechanisms lead...
An anelastic numerical model is employed to explore the dynamics of gravity waves (GWs) encountering a mesosphere inversion layer (MIL) having moderate static stability enhancement and weaker above. Instabilities occur within MIL when GW amplitude approaches that required for breaking due compression vertical wavelength accompanying increasing stability. Thus, MILs can cause large-amplitude GWs yield instabilities turbulence below altitude where they would otherwise arise. Smaller-amplitude...
Abstract This paper addresses the compressible nonlinear dynamics accompanying increasing mountain wave (MW) forcing over southern Andes and propagation into mesosphere lower thermosphere (MLT) under winter conditions. A stretched grid provides very high resolution of MW in a large computational domain. slow increase cross-mountain winds enables MWs to initially break extend higher altitudes thereafter. structure breaking is strongly modulated by static mean semidiurnal tide fields...
A compressible numerical model is applied for three-dimensional (3-D) gravity wave (GW) packets undergoing momentum deposition, self-acceleration (SA), breaking, and secondary GW (SGW) generation in the presence of highly-structured environments enabling thermal and/or Doppler ducts, such as a mesospheric inversion layer (MIL), tidal wind (TW), or combination MIL TW. Simulations reveal that ducts can strongly modulate dynamics. Responses modeled here include reflection, trapping, suppressed...