Tobias Bleninger
Federal University of Paraná, Brazil (UFPR)
Department of Environmental Engineering (DEA)
www.tobias.bleninger.info
Modeling of outfalls:
Status report and outlook
Tobias Bleninger
Federal University of Paraná, Brazil (UFPR)
Department of Environmental Engineering (DEA)
Head of Graduate Program on Water Resources and Environmental Engineering
Past chair of the IAHR / IWA Joint Committee on Marine Outfall Systems
INSTITUTE FOR HYDROMECHANICS, ENVIRONMENTAL FLUID MECHANICS GROUP
www.kit.edu
Tobias Bleninger
Federal University of Paraná, Brazil (UFPR)
Department of Environmental Engineering (DEA)
www.tobias.bleninger.info
Motivation
80
75
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60
55
50
45
40
35
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How and where to obtain
necessary dilution:
Order of 15
2
Tobias Bleninger
Federal University of Paraná, Brazil (UFPR)
Department of Environmental Engineering (DEA)
www.tobias.bleninger.info
Content
Mixing processes and scales
Screening
Dilution equations, nomograms, spreadsheet applications
Diffuser design
Jets and Plumes models
Mixing zone models
CFD
Diffuser location and impacts
Far-field models
Conclusions
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Mixing processes
Tobias Bleninger
Federal University of Paraná, Brazil (UFPR)
Department of Environmental Engineering (DEA)
www.tobias.bleninger.info
Intermediate-field:
boundary interaction,
buoyant spreading
Far-field:
ambient diffusion,
advection, degradation
Near-field: jet diffusion
(courtesy of Paolo Domenichini, Italy)
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Process scales
CORMIX (steady)
Tobias Bleninger
Federal University of Paraná, Brazil (UFPR)
Department of Environmental Engineering (DEA)
www.tobias.bleninger.info
Far-field models
(hydrostatic, unsteady)
3D CFD
(non-hydrostatic, steady)
Density currents
CorJet, Plumes
Visjet (steady)
Legal Mixing Zone
(fixed regulatory criteria)
(modified from Fischer et. al, 1979; Jirka & Lee, 1994;)
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Tobias Bleninger
Federal University of Paraná, Brazil (UFPR)
Department of Environmental Engineering (DEA)
www.tobias.bleninger.info
Case study
BHP Billiton expansion of mining operations at Olympic
Dam, South Australia
Includes construction and operation of desalination plant at
Point Lowly, Upper Spencer Gulf
BMT WBM and The Centre for Water Research (CWR) of
The University of Western Australia undertook numerical
modelling on behalf of BHP Billiton for EIS
Information kindly provided by Daniel Botelho (BMT WBM)
Reference: BMT WBM reports for EIS on Olympic Dam
(download from www.bmtwbm.com.au)
6
Tobias Bleninger
Federal University of Paraná, Brazil (UFPR)
Department of Environmental Engineering (DEA)
www.tobias.bleninger.info
Case study
Spencer Gulf:
tidally driven,
tides up to 2.7m,
shallow waters
60 km
300 km
Reference: BMT WBM reports for EIS on Olympic Dam
(download from www.bmtwbm.com.au)
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Tobias Bleninger
Federal University of Paraná, Brazil (UFPR)
Department of Environmental Engineering (DEA)
www.tobias.bleninger.info
Upper Spencer Gulf:
7-20 m deep
Point Lowly:
Planned outfall
location
20 km
Reference: BMT WBM reports
for EIS on Olympic Dam (download from
www.bmtwbm.com.au)
8
Tobias Bleninger
Federal University of Paraná, Brazil (UFPR)
Department of Environmental Engineering (DEA)
www.tobias.bleninger.info
• Diffuser length: 200m
• Pipe diameter: 2.1m
• Number of ports:50
• Port diameter: 175mm
• Port configuration: 60o angle to horizontal (alternating)
• Average depth of water: 20m
• Ambient salinity: 40 psu
• Effluent salinity: 78 psu
Reference: BMT WBM reports for EIS on Olympic Dam
• Effluent flow:
3.5 m³/s
(download from www.bmtwbm.com.au)
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Tobias Bleninger
Federal University of Paraná, Brazil (UFPR)
Department of Environmental Engineering (DEA)
www.tobias.bleninger.info
Dilution equations – single port (Fischer et al., 1979)
 Stagnant water, horizontal discharge:
centerline dilution


z
Sc = 0.54 Fo  0.38
+ 0.66 
DFo


5/3
for
POSITIVELY BUOYANT !
z
≥ 0.5 Fo
D
Densimetric Froude number:
Dilution equations – single port (Roberts et al., 1997)
 Stagnant water, 60° discharge:
Si = 1.6 x F
Sm = 2.6 x F
NEGATIVELY BUOYANT !
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Tobias Bleninger
Federal University of Paraná, Brazil (UFPR)
Department of Environmental Engineering (DEA)
www.tobias.bleninger.info
Design steps
Initial screening with parameter variations (here using
Roberts et al., 1997, still ambient water, no port elevation)
White: 45:1
Red: 85:1
 number of required ports
Reference: BMT WBM reports for EIS on Olympic Dam
(download from www.bmtwbm.com.au)
11
Jet models, including velocity, discharge angle and
port head variations
Tobias Bleninger
Federal University of Paraná, Brazil (UFPR)
Department of Environmental Engineering (DEA)
www.tobias.bleninger.info
Offshore slopes θB and discharge
height ho favor designs with lower
Lower discharge angles
allow nearshore placement discharge angles
in more shallow water
Bed inclination
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Discharge angles
e.g. CorJet as appropriately validated model
Jirka (2008), J.Hydr.Eng., 134, 116-120
Jirka (2004), Env. Fluid Mech., 4,1-56  single jet
Jirka (2006), Env. Fluid Mech., 6,43-100  multiport jets
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Tobias Bleninger
Federal University of Paraná, Brazil (UFPR)
Department of Environmental Engineering (DEA)
www.tobias.bleninger.info
Limitations of Jet models and dilution equations
Assume steady flow conditions
Self-similarity (base for integral model) for simple
phenomena only
No consideration of boundary interactions
No pollutant built-up!
14
Tobias Bleninger
Federal University of Paraná, Brazil (UFPR)
Department of Environmental Engineering (DEA)
www.tobias.bleninger.info
Flow classification for considerations of
boundary interactions
yc
x

= f  c , urF 
dF
 dF

Reference
E. Gungor and P. J.W. Roberts (2008) “Experimental Studies on Vertical Dense Jets in a Flowing
Current,” Submitted to Journal of Hydraulic Engineering, ASCE.
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D-CORMIX: Flow processes
Tobias Bleninger
Federal University of Paraná, Brazil (UFPR)
Department of Environmental Engineering (DEA)
www.tobias.bleninger.info
www.cormix.info
CORMIX key feature:
Bottom density
current analysis!
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Tobias Bleninger
Federal University of Paraná, Brazil (UFPR)
Department of Environmental Engineering (DEA)
www.tobias.bleninger.info
Case study: Olympic Dam
CORMIX with ambient current variation
350
300
Dilution
250
200
150
100
at Bottom Contact
50
at 100m
0
0
0.2
0.4
0.6
0.8
1
1.2
Ambient Current Velocity (m/s)
Reference: BMT WBM reports for EIS on Olympic Dam
(download from www.bmtwbm.com.au)
17
Tobias Bleninger
Federal University of Paraná, Brazil (UFPR)
Department of Environmental Engineering (DEA)
www.tobias.bleninger.info
Limitations of mixing zone models
Schematized (uniform and steady) ambient velocity and
density profiles, bathymetry
Single sources only, no multiple sources
Short to mid term assessment only
CORMIX: results +/- 50% standard deviation
Advantages:
Very fast, no need for calibration, few data need
Time-series applications, sensitivity studies, and design
evalutions easily possible
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Tobias Bleninger
Federal University of Paraná, Brazil (UFPR)
Department of Environmental Engineering (DEA)
www.tobias.bleninger.info
CFD against jet models
3D RANS University code
(Tang et al., JHE 134, 9, 2008)
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CFD against jet models
Tobias Bleninger
Federal University of Paraná, Brazil (UFPR)
Department of Environmental Engineering (DEA)
www.tobias.bleninger.info
(Tang et al., JHE 134, 9, 2008)
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CFD against field data
Tobias Bleninger
Federal University of Paraná, Brazil (UFPR)
Department of Environmental Engineering (DEA)
www.tobias.bleninger.info
(Tang et al., JHE 134, 9, 2008)
22
Tobias Bleninger
Federal University of Paraná, Brazil (UFPR)
Department of Environmental Engineering (DEA)
www.tobias.bleninger.info
CFD application for Olympic dam
OpenFOAM (free, www.openfoam.com)
Requires „meshing“ of geometry
B.C.: either no flow or ADCP profile
Bottom contoured to DEM data
4m x 4m x 0.5m
1m x 1m x 0.5m
0.5m x 0.5m x 0.5m
20m
2m x 2m x 0.5m
32m
48m
320m
320m
Reference: BMT WBM reports
for EIS on Olympic Dam (download from
www.bmtwbm.com.au)
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CFD application for Olympic dam
Tobias Bleninger
Federal University of Paraná, Brazil (UFPR)
Department of Environmental Engineering (DEA)
www.tobias.bleninger.info
Numerical stability issues: Adaptive mesh refinement
Reference: BMT WBM reports for EIS on Olympic Dam
(download from www.bmtwbm.com.au)
24
Tobias Bleninger
Federal University of Paraná, Brazil (UFPR)
Department of Environmental Engineering (DEA)
www.tobias.bleninger.info
CFD application for Olympic dam
Requires validation (here with lab studies from Roberts et
al. 97 and 87, no ambient velocities)
xi
Jet densimetric Froude number F=27.6
yctr
y
Di
Param.
Di/F
xi/dF
y/dF
Roberts 97
1.6
2.4
2.2
Roberts 87
1.03
2.08
CFD
0.98
2.05
1.85
Reference: BMT WBM reports for EIS on Olympic Dam
(download from www.bmtwbm.com.au)
25
Tobias Bleninger
Federal University of Paraná, Brazil (UFPR)
Department of Environmental Engineering (DEA)
www.tobias.bleninger.info
CFD application for Olympic dam
New findings (compared to jet models or experiments):
Reentrainment observed in CFD model and field, with 3-4
m stable salinity layer
CFD Model
Reference: BMT WBM reports for EIS
on Olympic Dam
(download from www.bmtwbm.com.au)
Field (fixed profiles over time)
Horizontal axis: time
Source:
www.watercorporation.com.au/_files/CockburnSoundFi
eldStudy.pdf page 26
27
CFD application for Olympic dam
Tobias Bleninger
Federal University of Paraná, Brazil (UFPR)
Department of Environmental Engineering (DEA)
www.tobias.bleninger.info
CFD for multiport and plume interaction, zero background
velocity, 45:1 dilution iso-surface
Exit velocity:
Uo = 2.6 m/s
Dilution: Di = 10
Uo = 3.6 m/s
Dilution: Di = 12
Uo = 5.9 m/s
Dilution: Di = 21
Uo = 8.9 m/s
Dilution: Di = 27
Reference: BMT WBM reports for EIS on Olympic Dam
(download from www.bmtwbm.com.au)
28
CFD application for Olympic dam
Tobias Bleninger
Federal University of Paraná, Brazil (UFPR)
Department of Environmental Engineering (DEA)
www.tobias.bleninger.info
Each ambient flow scenario requires new computation
45:1 dilution iso-surfaces and 100 m curtains at ebb and flood tides
Reference: BMT WBM reports for EIS on Olympic Dam
(download from www.bmtwbm.com.au)
29
Tobias Bleninger
Federal University of Paraná, Brazil (UFPR)
Department of Environmental Engineering (DEA)
www.tobias.bleninger.info
CFD application for Olympic dam
Improved optimization (compared to jet models) of rosette
configuration
Reference: BMT WBM reports for EIS on Olympic Dam
(download from www.bmtwbm.com.au)
32
Tobias Bleninger
Federal University of Paraná, Brazil (UFPR)
Department of Environmental Engineering (DEA)
www.tobias.bleninger.info
Limitations of CFD models
Mesh generation, stability analysis and validation required
Requires long computation times
Often only feasible for steady flow conditions (otherwise
require clusters)
Near-field and short term only
Free surface representations are difficult (often rigid lid)
Advantages
Simulates very low velocity cases (difficult in CORMIX)
Simulates complex structures or ambient conditions
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FF model (ELCOM)
Far-field models
Tobias Bleninger
Federal University of Paraná, Brazil (UFPR)
Department of Environmental Engineering (DEA)
www.tobias.bleninger.info
31 layers
Shallow water (hydrostatic) solver
Grid sizes from 40m to 5km
B.C. from ocean model (HYCOM)
Non-uniform and unsteady
meteorological forcing
Reference: BMT WBM reports for EIS on Olympic Dam
(download from www.bmtwbm.com.au)
34
Far-field model: validation
Tobias Bleninger
Federal University of Paraná, Brazil (UFPR)
Department of Environmental Engineering (DEA)
www.tobias.bleninger.info
Reference: BMT WBM reports for EIS on Olympic Dam
35
Tobias Bleninger
Federal University of Paraná, Brazil (UFPR)
Department of Environmental Engineering (DEA)
www.tobias.bleninger.info
Limitations of Far field models
Outfall structure and near-field processes not resolved
Outfall assessment only with coupled modeling
Requires large number of measured data for B.C. and
calibration (bathymetry, metereogical and hydrological
forcing (winds, solar, radation, river discharges), tides,
velocity and density profiles at open boundaries (usually
from nested model))
Advantages
Very good and important tool for system analysis
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Model linking
Tobias Bleninger
Federal University of Paraná, Brazil (UFPR)
Department of Environmental Engineering (DEA)
www.tobias.bleninger.info
 Determination of corresponding cells considering plume geometry (thickness, width,
position)
 Calculation of corresponding fluxes as sources or sinks for ff-model
Reference: Bleninger et al., 2008
42
Coupling location
Tobias Bleninger
Federal University of Paraná, Brazil (UFPR)
Department of Environmental Engineering (DEA)
www.tobias.bleninger.info
 No coupling
neglect plume geometry
 Vertical coupling
consider thickness of
plume
 Complete coupling
consider thickness,
width and position of
plume
Reference: Bleninger et al., 2008
43
Tobias Bleninger
Federal University of Paraná, Brazil (UFPR)
Department of Environmental Engineering (DEA)
www.tobias.bleninger.info
Coupling location
Time step 87
11-Feb-1998 15:00:00
5.0
Vertical coupling
Konzentration [kg/m³]
No coupling
Bottom layer
0
1.0
[kg/m³]
Full coupling
0.5
Bottom layer
0.5
Bottom layer
0
1.0
[kg/m³]
0
Time step 111
12-Feb-1998 15:00:00
5.0
Vertical coupling
Konzentration [kg/m³]
No coupling
Bottom layer
0
1.0
[kg/m³]
Full coupling
0.5
Bottom layer
0
1.0
[kg/m³]
0.5
Bottom layer
0
Reference: Bleninger et al., 2008
44
Tobias Bleninger
Federal University of Paraná, Brazil (UFPR)
Department of Environmental Engineering (DEA)
www.tobias.bleninger.info
Coupling parameters
Passive coupling (e.g. Olympic Dam study)
(only pollutant mass fluxes as sources and sinks)
Far-field source
CFD or jet model conc. results
ff-grid cell
Reference: BMT WBM reports for EIS on Olympic Dam
Dynamic coupling (e.g. cooling water discharge)
(significant nf-induced volume fluxes and/or momentum as sources and sinks)
Morelissen et al., 2014 (this conference)
46
Tobias Bleninger
Federal University of Paraná, Brazil (UFPR)
Department of Environmental Engineering (DEA)
www.tobias.bleninger.info
Final results of passivly coupled
CFD with FF model for Olympic Dam study
Source: Daniel Botelho, Olympic Dam Mine Expansion – Water Quality
Modelling for the EIA of Spencer Gulf Desalination Plant (BHP Billiton)
Reference: BMT WBM reports for EIS on Olympic Dam
(download from www.bmtwbm.com.au)
50
Conclusions
Tobias Bleninger
Federal University of Paraná, Brazil (UFPR)
Department of Environmental Engineering (DEA)
www.tobias.bleninger.info
Dilution equations and length scale analysis: fast screening
analysis and flow classification
Jet models, Mixing Zone Models and CFD complement each
other and provide base for ff-coupling
Large-scale impact assessment requires FF model coupling:
Passive: small flows, e.g. wastewater, RO brine
Dynamic: large flows, e.g. cooling waters or discharges
into stagnant, shallow waters
Future challenges: Water Quality and Eco-models
Transformation processes and eco-system parameters
still highly sensitive and difficult to validate
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Tobias Bleninger
Federal University of Paraná, Brazil (UFPR)
Department of Environmental Engineering (DEA)
www.tobias.bleninger.info
References and links
Journal of Applied Water Engineering
Research (JAWER)
IAHR, WCCE, Taylor and Francis
www.tandfonline.com/tjaw
and
 best ICDEMOS articles considered!
IAHR / IWA Committee on Marine Outfall Systems
www.outfalls.bleninger.info
 open meeting today 17h!
Outfall modeling discussion
 Tuesday, 16:30h!
MEDRC research project on brine discharge
modeling
http://www.ifh.unikarlsruhe.de/science/envflu/research/brinedis/
Contact:
bleninger@ufpr.br, www.tobias.bleninger.info
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