Saturated

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Saturated unsaturated flow and multiphase
transport modeling
by Michel E. Rahbeh Rabi H. Mohtar Tong Zhai
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Contents

• Introduction
• Governing Equations
• I/O for the ground water flow model
• I/O for the ground water transport model
• I/O for the air sparging/ soil vapor extraction
  flow component
• I/O for the air sparging/ soil vapor extraction
  multiphase transport component.
• Sample output
• Transport in saturated porous media
• Unsaturated flow (air sparging)
• Multiphase transport
• Web application

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Introduction

• The model was developed to solve specifically for
  contaminant removal by advective air flux induced
  by air injection (air sparging) or extraction
  (soil vapor extraction)
• However the same code can be used to solver for
  conventional heterogeneous flow and contaminant
  transport problems

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Introduction

• Volatile Organic Contaminant (VOC) can removed
  from soil and ground water by an advective air
  flux.
• Advective air flux can be either induced by
  extracting air (Soil Vapor Extraction, SVE), or
  injecting air (Soil sparging AS).
• The SVE and AS can be operated separately or
  simultaneously as shown in the following figure

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• As air flowing upward the contaminant is
  mobilized into the advective air stream.
• Also the oxygenation of the subsurface may
  trigger aerobic metabolism of the organic
  contaminants

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GOAL To develop suitable tool to help understand
mass transfer processes during air advective air
flux, in order to aid in the design and
operation of remediation systems that involve
advective air flux such air sparging and Soil
vapor Extraction (AS/SVE).

• The model consists of two module
• Multiphase transient module, and
• unsaturated steady flow module

kdeg
kd Sorption/desorption ks Stripping kv
volitalization kdisdissolution kdeg
biodegradation
Solid Phase Ss
Aqueous phase Caq
Non-aqueous phase Cnaq
Total Removal
kd
kdis
kv
Gaseous phase Cg
ks
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Unsaturated flow model
kdeg
kd Sorption/ desorption ks Stripping kv
volitalization kdisdissolution kdeg
biodegradation
Solid Phase Ss
kdis
Aqueous phase Caq
Non-aqueous phase Cnaq
Total Removal
kd
kv
ks
Gaseous phase Cg
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Aqueous phase
kdeg
kd Sorption/ desorption ks Stripping kv
volitalization kdisdissolution kdeg
biodegradation
Solid Phase Ss
Aqueous phase Caq
Non-aqueous phase Cnaq
Total Removal
kd
kdis
kv
ks
Gaseous phase Cg
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Gaseous Phase
kdeg
kd Sorption/desorption ks Stripping kv
volitalization kdisdissolution kdeg
biodegradation
Solid Phase Ss
Aqueous phase Caq
Non-aqueous phase Cnaq
Total Removal
kd
kdis
kv
ks
Gaseous phase Cg
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Solid Phase
kdeg
Solid Phase Ss
kd
Aqueous phase Caq
Non-aqueous phase Cnaq
Total Removal
kd Sorption/ desorption ks Stripping kv
volitalization kdisdissolution kdeg
biodegradation
kdis
kv
ks
Gaseous phase Cg
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Non Aqueous Liquid Phase
kdeg
Solid Phase Ss
Aqueous phase Caq
Non-aqueous phase Cnaq
Total Removal
kd Sorption/ desorption ks Stripping kv
volitalization kdisdissolution kdeg
biodegradation
kdis
kd
kv
ks
Gaseous phase Cg
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Numerical Formulation
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First order mass transfer coefficients
Mass Transfer Correlation Reference
Air-water ks10-2.49Dmg0.16vg0.84d500.55KH-0.61 Chao et al. (1998)
NAPL-air kv10-0.42Dmg0.38vg0.62d500.44 Wilkins et al. (1995)
NAPL-water kdis10-2.69Dmaq1vaq0.60d50-0.73 Powers (1992)
Soil water kd100.301KD-0.668 Brusseau and Rao (1989)
Soil-water kdD/?2 Ball and Roberts (1991)
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Input/output for air sparging/SVE air flow
component

• Input
• Boundary conditions Capillary pressure
• Intrinsic permeability
• Coefficients for pressure-saturation
  relationship. The pore size distribution index
  (Lamda) for Brooks-Corey relation.
• Output
• Capillary head distribution

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Input/output for the Ground water flow

• Input
• Hydraulic conductivity or transmissivity
• Boundary conditions water table heads or
  piezometric pressure.
• Output
• water table heads or piezometric pressure
  distribution

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Input / output for the ground water transport

• Input
• Dispersivity
• Ground water velocities or, water table heads or
  piezometric pressure distribution.
• Initial condition concentration profile
  C(0,x,y)
• Output
• Concentration profile C(t,x,y)

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Input/output for air sparging/SVE Multiphase
Flow Component
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Example output ground water transport
Comparison between analytical and numerical
solutions of instantaneous injection of a solute
unit mass in one-dimensional single phase, where
Pv1 and PD0.05. The continuous lines represent
the numerical solution, where as, the data points
analytical solutions the
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Example output ground water transport
Comparison between analytical and numerical
solutions of continuous solute injection in
one-dimensional single phase, where Pv1,
Pe0.05. The continuous lines represent the
numerical solution, where as, the data points
analytical solutions
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Example output ground water transport
The comparison between the analytical and
numerical solution of an instantaneous injection
of a unit mass of a contaminant in
two-dimensional single phases domain, where
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Example output Air sparging flow component
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Example output air sparging multiphase component
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WEB APPLICATION