Dissipation Independence of the Inertial-Convective Range in a Passive Scalar Model

1996 ◽  
Vol 77 (13) ◽  
pp. 2674-2677 ◽  
Author(s):  
Gregory Eyink ◽  
Jack Xin
Keyword(s):  
Passive Scalar ◽  
Scalar Model

scholarly journals Structures and Intermittency in a Passive Scalar Model

1997 ◽  
Vol 79 (10) ◽  
pp. 1849-1852 ◽  
Author(s):  
M. Vergassola ◽  
A. Mazzino
Keyword(s):  
Passive Scalar ◽  
Scalar Model

scholarly journals The spiral wind-up and dissipation of vorticity and a passive scalar in a strained planar vortex

1999 ◽  
Vol 398 ◽  
pp. 245-270 ◽  
Author(s):  
ANDREW P. BASSOM ◽  
ANDREW D. GILBERT
Keyword(s):  
Passive Scalar ◽  
Step Function ◽  
Scalar Model ◽  
Azimuthal Component ◽  
Vortex Model ◽  
Vorticity Distribution ◽  
Rebound Phenomenon ◽  
The Mean ◽  
Asymptotic Formulation ◽  
External Strain

The response of a Gaussian vortex to a weak time-dependent external strain field is studied numerically. The cases of an impulsive strain, an on–off step function, and a continuous random strain are considered. Transfers of enstrophy between mean and azimuthal components are observed, and the results are compared with an analogous passive scalar model and with Kida's elliptical vortex model.A ‘rebound’ phenomenon is seen: after enstrophy is transferred from mean to azimuthal component by the external straining field, there is a subsequent transfer of enstrophy back from the azimuthal component to the mean. Analytical support is given for this phenomenon using Lundgren's asymptotic formulation of the spiral wind-up of vorticity. Finally the decay of the vortex under a continuous random external strain is studied numerically and compared with the passive scalar model. The vorticity distribution decays more slowly than the scalar because of the rebound phenomenon.

scholarly journals Experimental and Numerical Investigation of Mixing Phenomena in Double-Tee Junctions

Water ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 1198 ◽  
Author(s):  
Luka Grbčić ◽  
Lado Kranjčević ◽  
Ivana Lučin ◽  
Zoran Čarija
Keyword(s):  
Numerical Models ◽  
Passive Scalar ◽  
Calibration Procedure ◽  
Multiphase Model ◽  
Scalar Model ◽  
Pipe System ◽  
Turbulent Schmidt Number ◽  
Wide Range ◽  
Tee Junction ◽  
The Relationship

This work investigates mixing phenomena in a pressurized pipe system with two sequential Tee junctions and experiments are conducted for a range of different inlet flow ratios, varying distances between Tee junctions and two pipe branching configurations. Additionally, obtained experimental results are compared with results from previous studies by different authors and are used to validate the numerical model using the open source computational fluid dynamics toolbox OpenFOAM. Two different numerical approaches are used—Passive scalar model and Multiphase model. It is found that both numerical models produce similar results and that they are both greatly dependent on the turbulent Schmidt number. After the calibration procedure, both models provided good results for all investigated flow ratios, double-Tee junction distances, and pipe branching configurations, therefore both numerical models can be applied for a wide range of pipe networks configurations, but passive scalar model is the viable choice due to its much higher computational efficiency. Obtained results also describe the relationship between the double-Tee distances and complete mixing occurrence.

Large eddy simulation of evolution of a passive scalar in plane jet

AIAA Journal ◽  
2001 ◽  
Vol 39 ◽  
pp. 1509-1516 ◽  
Author(s):  
C. Le Ribault ◽  
S. Sarkar ◽  
S. A. Stanley
Keyword(s):  
Large Eddy Simulation ◽  
Passive Scalar ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Plane Jet

scholarly journals Ventilation of a Mid-Size City under Stable Boundary Layer Conditions: A Simulation Using the LES Model PALM

Atmosphere ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 401
Author(s):  
Jonathan Biehl ◽  
Bastian Paas ◽  
Otto Klemm
Keyword(s):  
Boundary Layer ◽  
Stable Boundary Layer ◽  
Passive Scalar ◽  
City Center ◽  
Street Canyons ◽  
Stable Boundary ◽  
Northwest Germany ◽  
Stable Conditions ◽  
Les Model ◽  
The City

City centers have to cope with an increasing amount of air pollution. The supply of fresh air is crucial yet difficult to ensure, especially under stable conditions of the atmospheric boundary layer. This case study used the PArallelized Large eddy simulation (LES) Model PALM to investigate the wind field over an urban lake that had once been built as a designated fresh air corridor for the city center of Münster, northwest, Germany. The model initialization was performed using the main wind direction and stable boundary layer conditions as input. The initial wind and temperature profiles included a weak nocturnal low-level jet. By emitting a passive scalar at one point on top of a bridge, the dispersion of fresh air could be traced over the lake’s surface, within street canyons leading to the city center and within the urban boundary layer above. The concept of city ventilation was confirmed in principle, but the air took a direct route from the shore of the lake to the city center above a former river bed and its adjoining streets rather than through the street canyons. According to the dispersion of the passive scalar, half of the city center was supplied with fresh air originating from the lake. PALM proved to be a useful tool to study fresh air corridors under stable boundary layer conditions.

scholarly journals A Code for Simulating Heat Transfer in Turbulent Channel Flow

Mathematics ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 756
Author(s):  
Federico Lluesma-Rodríguez ◽  
Francisco Álcantara-Ávila ◽  
María Jezabel Pérez-Quiles ◽  
Sergio Hoyas
Keyword(s):  
Heat Transfer ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Turbulent Channel Flow ◽  
Passive Scalar ◽  
Direct Numerical Simulations ◽  
Time Dependent ◽  
Navier Stokes ◽  
Thermal Flow ◽  
Navier Stokes Equations

One numerical method was designed to solve the time-dependent, three-dimensional, incompressible Navier–Stokes equations in turbulent thermal channel flows. Its originality lies in the use of several well-known methods to discretize the problem and its parallel nature. Vorticy-Laplacian of velocity formulation has been used, so pressure has been removed from the system. Heat is modeled as a passive scalar. Any other quantity modeled as passive scalar can be very easily studied, including several of them at the same time. These methods have been successfully used for extensive direct numerical simulations of passive thermal flow for several boundary conditions.

Sign in / Sign up

Export Citation Format

Share Document