Browsing by Subject "Turbulent flow"

Article

An analytical solution for rapidly distorted turbulent shear flow in a rotating frame

Akylas, Evaggelos; Kassinos, Stavros C.; Langer, A. C. (2006)

In this study we apply rapid distortion theory to the case of nonstratified homogeneous turbulence that is sheared in a frame that counter-rotates at a rate that matches in magnitude the rotation associated with the mean ...

Article

The ASBM-SA turbulence closure: Taking advantage of structure-based modeling in current engineering CFD codes

Panagiotou, C. F.; Kassinos, Stavros C.; Aupoix, B. (2015)

Structure-based turbulence models (SBM) carry information about the turbulence structure that is needed for the prediction of complex non-equilibrium flows. SBM have been successfully used to predict a number of canonical ...

Article

Coherent structures in oscillating turbulent boundary layers over a fixed rippled bed

Grigoriadis, D. G. E.; Balaras, E.; Dimas, A. A. (2013)

Coherent structures generated by oscillating turbulent boundary layers with or without a unidirectional current over a fixed, rippled bed are presented. The effect of ripple height and current intensity on the characteristics ...

Article

The contribution of active and inactive structures to the statistics of a turbulent pipe flow

Stylianou, F. S.; Kassinos, Stavros C. (2017)

The current study is a short follow-up to our most recent work (Stylianou et al., 2016), where among other things we have presented an effective criterion suitable for distinguishing large-scale coherent structures with ...

Conference Object

Development of an efficient two-phase 3D numerical wave flume

Frantzis, C.; Grigoriadis, D. G. E. (Society of Petroleum Engineers, 2017)

In the present study an efficient two-phase 3D numerical wave flume was developed, tested and validated. The most important advantage over conventional numerical wave flumes is the use of a constant coefficient Poisson ...

Article

Direct numerical simulation of particle laden flow in a human airway bifurcation model

Stylianou, F. S.; Sznitman, J.; Kassinos, Stavros C. (2016)

During the delivery of inhaled medicines, and depending on the size distribution of the particles in the formulation, airway bifurcations are areas of preferential deposition. Previous studies of laminar flow through airway ...

Conference Object

Effect of turbulent pulsating flow around a near-wall submerged cylinder on the potential motion of bed and suspended loads

Fonias, E. N.; Grigoriadis, D. G. E. (International Society of Offshore and Polar Engineers, 2016)

In the present work, the pulsating flow around a submerged cylinder close to the impermeable seabed is examined by means of Large Eddy Simulations (LES). A Reynolds number equal to Re = 5000 is considered, based on the ...

Article

Efficient treatment of complex geometries for large eddy simulations of turbulent flows

Grigoriadis, D. G. E.; Bartzis, J. G.; Goulas, A. (2004)

Incompressible turbulent flow over a backward facing step at Reh=5100 is investigated by large eddy simulations (LES). The ratio of the oncoming boundary layer thickness δ to the step height h was set to 1.2. Additionally ...

Conference Object

Fully turbulent flow in a physiologically realistic human airway bifurcation

Stylianou, F. S.; Kassinos, Stavros C. (TSFP-9, 2015)

Recent computational studies have shown that the airflow in the upper human airways is turbulent during much of the respiratory cycle. A feature of respiratory airflow that poses a challenge to computations based on ...

Article

A general framework for computing the turbulence structure tensors

Stylianou, F. S.; Pecnik, R.; Kassinos, Stavros C. (2015)

Good measures of the turbulence structure are important for turbulence modeling, flow diagnostics and analysis. Structure information is complementary to the componentality anisotropy that the Reynolds stress tensor carries, ...

Article

Large Eddy Simulation of near-bed pipelines in oscillatory flow

Fonias, E. N.; Grigoriadis, D. G. E. (2018)

A series of unsteady, three-dimensional numerical simulations of the incompressible, oscillatory flow around a near-bed pipeline is presented. A flow at Reynolds number equal to Reαo=20,000 with respect to the oscillatory ...

Conference Object

Large eddy simulation of sediment transport for the pulsating flow past a cylinder over a horizontal bed

Fonias, E. N.; Grigoriadis, D. G. E. (International Society of Offshore and Polar Engineers, 2015)

In the present work, the suspended, pulsating incompressible flow past a submerged cylinder was examined by means of Large Eddy Simulations (LES). A layer of sandy inertial particles was allowed to move between the cylinder ...

Article

Large-eddy simulation of wave turbulent boundary layer over rippled bed

Grigoriadis, D. G. E.; Dimas, A. A.; Balaras, E. (2012)

Large-eddy simulation (LES) of turbulent boundary layer induced by external oscillatory flow without or with a unidirectional component over rippled bottom is presented. These flows represent prototype turbulent flows of ...

Article

Large-eddy simulations of the turbulent Hartmann flow close to the transitional regime

Sarris, I. E.; Kassinos, Stavros C.; Carati, D. (2007)

A series of large-eddy simulations (LES) of turbulent and transitional channel flows of a conductive fluid under the effect of a uniform magnetic field applied in the wall-normal direction, usually referred to as Hartmann ...

Article

LES of the flow past a rectangular cylinder using the immersed boundary concept

Grigoriadis, D. G. E.; Bartzis, J. G.; Goulas, A. (2003)

Incompressible turbulent flow past a long square cylinder is investigated using large eddy simulations LES). Results are presented and compared with available experimental databases for a Reynolds number Red = 22 000. The ...

Article

Linear analysis of generalized turbulent hyperbolic flow in a rotating frame

Langer, C. A.; Akylas, Evaggelos; Kassinos, Stavros C. (2007)

We apply inviscid rapid distortion theory to the generalized case of turbulent hyperbolic flow in a rotating frame and investigate the dependence of the evolution of the turbulent kinetic energy on the frame rotation rate. ...

Article

MHD flow past a circular cylinder using the immersed boundary method

Grigoriadis, D. G. E.; Sarris, I. E.; Kassinos, Stavros C. (2010)

The immersed boundary method (IB hereafter) is an efficient numerical methodology for treating purely hydrodynamic flows in geometrically complicated flow-domains. Recently Grigoriadis et als. [1] proposed an extension of ...

Conference Object

Numerical simulations of turbulent flow in an eccentric annulus of unit eccentricity

Kanaris, N.; Albets-Chico, X.; Kassinos, Stavros C. (TSFP-9, 2015)

In this study, we perform Direct Numerical Simulations (DNS) of fully developed turbulent flows in eccentric annuli having different diameter ratios. Annuli of unit eccentricity, and diameter ratios of 0.2591 and 0.1395 ...

Article

On the linear stability of turbulent plane strain flow in a rotating frame

Akylas, Evaggelos; Langer, C. A.; Kassinos, Stavros C.; Demosthenous, E. (2007)

We apply inviscid rapid distortion theory to the limiting hyperbolic case of turbulent plain strain flow in a rotating frame and investigate the dependence of the evolution of the turbulent kinetic energy on the frame ...

Article

Rapid shear of initially anisotropic turbulence in a rotating frame?

Akylas, Evaggelos; Kassinos, Stavros C.; Langer, C. A. (2007)

In the present study, we investigate, using inviscid rapid distortion theory, the evolution of sheared turbulence in a rotating frame as a function of the rotation rate (including stable, transitional, and unstable regimes), ...