**PROBLEM
DEFINITION**

Two buildings are exposed to a side wind and obstruct the flow, generating recirculations and turbulence from shear. A pollution source is located somewhere in the field. The goal is to solve for the flow field and concentration of pollutant throughout the field. Turbulence is resolved with a Large Eddy Simulation; subgrid turbulence is parameterized using a two-parameter k-e model. We are considering steady-state conditions. The geometry and initial/boundary conditions are illustrated below:

**EXECUTABLE AND INPUT
FILE**

Input file (PROB.INP)

Windows 3.x/9x/ME/2000/NT Executable (CANYON.EXE)

Obtain both files in a compressed package (CANYON.ZIP)

**SAMPLE
RESULTS**

These simulation results and graphics were generated by Carlos and Paula Agudelo. The graphics were generated with IDL.

Turbulent kinetic energy contours generated by the wind shear:

Concentration contours and velocity profiles for a source located between buildings (generated using IDL):

Concentration contours and velocity profiles for a source located between buildings (generated using IDL):

**Sample results input
file (PROB.INP)**

*

* ===[ PARAMETER'S FILE FOR CANYON - All units in SI ]=================

*

===[ DIMENSIONS OF FIELD ]=============================================

Length of upwind, Bldg1, Canyon, Bldg2, and downwind section [ ALUP, ALBL1, ALMID, ALBL2, ALDN ]

0.5, 0.25, 0.25, 0.25, 2.0

Height of Bldg 1, Bldg 2, and Free space above bldg 1 [ HGBL, HGBL2, HGUP ]

0.2, 0.1, 0.4

===[ GRID POINTS ]=====================================================

x-direction: # of cells for upwind, Bldg1, Canyon, Bldg2, and downwind sections

20, 20, 20, 20, 20

y-direction: # of cells for building and above-bldg 1 sections

30, 60

===[ LOCATION OF POINT SOURCE ]========================================

X,Y location of source [ XSRC, YSRC ]

0.875, 0.01

===[ COORDINATES OF MONITORING POINT ]=================================

I,J monitoring location [ IMON, JMON ]

5, 5

===[ GET INFO FOR BOUNDARY CONDITIONS ]================================

Velocity at inlet of flow domain [ UIN ]

1.0

Turbulence intensity factor at inlet of flow domain [ TURBIN ]

0.03

Length scale factor at inlet of flow domain [ ALAMDA ]

0.005

===[ PROGRAM CONTROL PARAMETERS ]======================================

Maximum number of iterations [ MAXIT ]

150

Maximum residual [ SORMAX ]

0.005

Index for field printout [ INDPRI ]

1000

===[ DEPENDENT VARIABLES ]=============================================

Solve for hydrodynamic cycle (U,V,P) [.TRUE.=Yes, .FALSE.=No]

.true.

Solve for concentration equation [ INCALT ]

.true.

Solve for turbulence (kapa,epsilon) [.TRUE.=Yes, .FALSE.=No]

.TRUE.

===[ NUMBER OF SWEEPS FOR ALL VARIABLES ]==============================

Number of application of line iteration for u-, v- equations [ LITERU ]

2

Number of application of line iteration for p'-equation [ LITERP ]

5

Number of application of line iteration for C-equation [ LITERT ]

2

Number of application of line iteration for tubulence closure eqns [ LITERK ]

2

===[ UNDER-RELAXATION ]================================================

Under relaxation factor for u-, V-velocity [ URFU ]

0.5

Under relaxation factor for pressure correction [ URFP ]

0.25

Under relaxation factor for temperature [ URFT ]

0.7

Under relaxation factor for energy dissipation [ URFE ]

0.7

Under relaxation factor for turbulence energy [ URFK ]

0.7

Under relaxation factor for viscosity [ URFVIS ]

0.7

===[ COORDINATES OF FIXED PRESSURE POINT ]=============================

Axial fixed-pressure location index [ IPREF, JPREF ]

2, 2

===[ FLUID PROPERTIES ]================================================

Fluid density at inlet of calculation domain [ DENSIT ]

1.0

Laminar fluid viscosity [ VISCOS ]

1e-5

Laminar Prandtl number [ PRANDT ]

1.0

===[ CONSTANTS OF TURBULENCE MODEL K-E ]===============================

Constants of turbulence model [ CMU,CD,C1,C2 ]

0.09,1.0,1.44,1.92

Von Karman constant [ CAPPA ]

0.4187

Integration constant of turbulence model [ ELOG ]

9.793

Constant of turbulence model in k-, e-, t-equations [ PRTE, PRED, PRT ]

1.0, 1.3, 0.9

===[ SOLVER SELECTION ]================================================

Solver for u-,V-velocity equations [ ISLVU ]

1

Solver for pressure correction equationn [ ISLVP ]

1

Solver for concentration equations [ ISLVT ]

1

Solver for turbulence closure equations [ ISLVE ]

1

===[ FILING SYSTEM ]===================================================

Name of main output file [ OUTFIL ]

result.out

Read IN restart file [ INREAD ]

.TRUE.

Save restart file at end of run [ INWRITE ]

.TRUE.

Name of restart file [ RSTFIL ]

restart.dat