The turbulent blood flow through an aortic coarctation in a 63-year old female patient was studied experimentally using magnetic resonance imaging (MRI), and numerically using computational fluid dynamics (CFD), before and after catheter intervention. Turbulent kinetic energy (TKE) was computed in the numerical model using large eddy simulation and compared with direct in vivo MRI measurements....

Large-eddy simulation (LES) is used to investigate turbulence in a marginally-unstable stratified shear layer motivated by the observation of deep-cycle turbulence in the upper Equatorial Undercurrents. The initial condition consists of uniform shear and stratification profiles, and a constant gradient Richardson number Rig = 0.25. A constant wind stress forces turbulence in the upper surface l...

We present a combined experimental and computational study of the dual-stream exhaust of a supersonic turbofan engine with noise-suppressing deflectors installed in the fan stream. The focus is on validating the computational code, extracting turbulent kinetic energy (TKE) trends, and connecting those trends to the measured noise reduction. We consider two operating conditions, a “cold” conditi...

Several bulk model–based entrainment parameterizations for the atmospheric convective boundary layer (CBL) with wind shear are reviewed and tested against large-eddy simulation (LES) data to evaluate their ability to model one of the basic integral parameters of convective entrainment—the entrainment flux ratio. Test results indicate that many of these parameterizations fail to correctly reprod...

We present results from laboratory experiments in a wave flume with and without a sediment bed to investigate the turbulent structure and sediment dynamics of wave-supported mud layers. The presence of sediment on the bed significantly alters the structure of the wave boundary layer relative to that observed in the absence of sediment, increasing the TKE by more than a factor of 3 at low wave o...

Aerial migrants commonly face atmospheric dynamics that may affect their movement and behaviour. Specifically, bird flight mode has been suggested to depend on convective updraught availability and tailwind assistance. However, this has not been tested thus far since both bird tracks and meteorological conditions are difficult to measure in detail throughout extended migratory flyways. Here, we...

PURPOSE To evaluate the feasibility of generalized phase-contrast magnetic resonance imaging (PC-MRI) for the noninvasive assessment of fluctuating velocities in cardiovascular blood flow. MATERIALS AND METHODS Multidimensional PC-MRI was used in a generalized manner to map mean flow velocities and intravoxel velocity standard deviation (IVSD) values in one healthy aorta and in three patients...

It is noted that the results of recent experiments on the enhancement of turbulent kinetic energy (TKE) dissipation below surface waves can be stated as follows. TKE dissipation is enhanced by a factor 15Hws/z at depths 0.5Hws < z < 20Hws with respect to the wall-layer result ǫ = u ∗w/κz, where u∗w is the friction velocity in water and Hws is the significant windsea wave height. For open ocean ...

A 1D Canopy Interface Model (CIM) is developed to act as an interface between a meso-scale and a micro-scale atmospheric model and to better resolve the surface turbulent fluxes in the urban canopy layer. A new discretisation is proposed to solve the TKE equation finding solutions that remain fully concordant with the surface layer theories developed for neutral flows over flat surfaces. A corr...