Accession Number:

ADA505936

Title:

DNS and RANS Simulation of Dispersion Downstream of an Obstacle

Descriptive Note:

Conference paper

Corporate Author:

BOLOGNA UNIV (ITALY)

Personal Author(s):

• Rossi, Riccardo
• Iaccarino, Gianluca

Report Date:

2008-12-01

Pagination or Media Count:

9.0

Abstract:

Dispersion in the wake of an obstacle is studied as a step towards the analysis of bio-agent release in urban environments. Available experimental measurements are used to compare in details numerical predictions obtained using Reynolds-Averaged Navier-Stokes RANS techniques and Direct Numerical Simulations DNS. In particular, turbulent scalar fluxes are compared to assess the quality of simple closure based on eddy diffusivity assumptions. The results obtained using different RANS closures show considerable spread in the results, with satisfactory agreement obtained by one model which predicts very low levels of turbulence in the obstacle wake. On the other hand, DNS is fairly accurate but very sensitive to adopted inflow conditions. Finally, in terms of the turbulent fluxes the RANS models qualitatively represent the vertical flux but fail to predict the streamwise components while DNS predictions, at least for the highest Reynolds number considered, represent both components with a fairly good level of accuracy.

Descriptors:

• *NAVIER STOKES EQUATIONS
• *DISTRIBUTED INTERACTIVE SIMULATION
• EXPERIMENTAL DATA
• DISPERSING
• MODELS
• FLUX(RATE)
• NUMERICAL ANALYSIS
• ACCURACY
• TURBULENCE
• EDDIES(FLUID MECHANICS)
• MATHEMATICAL PREDICTION
• VERTICAL ORIENTATION
• WAKE
• LOW LEVEL
• FLOW
• SCALAR FUNCTIONS
• DIFFUSIVITY
• REYNOLDS NUMBER
• URBAN AREAS
• CLOSURES
• SIMULATION
• MEASUREMENT

Subject Categories:

• Numerical Mathematics
• Computer Programming and Software

Distribution Statement:

APPROVED FOR PUBLIC RELEASE