Transcript Modeling Flow Through Porous Media
Workshop 4 Flow Through Porous Media
Introduction to CFX
Pardad Petrodanesh.Co
Lecturer: Ehsan Saadati [email protected]
www.petrodanesh.ir
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WS4-1 April 28, 2009 Inventory #002599
WS4: Flow Through Porous Media
Introduction
• This workshop demonstrates how to model porous media in CFX.
• It models a catalytic converter. Nitrogen flows in through the inlet with a uniform velocity of 10 m/s, passes through a ceramic monolith substrate with square shaped channels, and then exits through the outlet.
• The substrate is impermeable in the X and Y direction, which is modeled by specifying loss coefficients 2 orders of magnitude higher than in the Z direction.
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WS4-2 Ceramic Monolith Substrate
Workshop Supplement
April 28, 2009 Inventory #002599
WS4: Flow Through Porous Media
Starting CFX-Pre
1.
Workshop Supplement
Start Workbench and save the Project as
cat_converter.wbpj
2.
Drag
CFX
into the Project Schematic from the
Component Systems
toolbox and name the system
Porous
3.
Start CFX-Pre by double clicking
Setup
4.
When CFX-Pre opens, right-click
Mesh
and select
Import Mesh > ICEM CFD
. Select the file
catconv.cfx5
5.
Keep the
Mesh Units
in
m
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WS4-3 April 28, 2009 Inventory #002599
WS4: Flow Through Porous Media
Material Import
1.
Right-click
Materials Import Library Data
and select
2.
Select
N2 Ideal Gas
by expanding the
Calorically Perfect Ideal Gases
branch
3.
Click
OK
Workshop Supplement
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WS4-4 April 28, 2009 Inventory #002599
WS4: Flow Through Porous Media
Fluid Domain Setup
1.
Double-click
Default Domain
2.
For
Fluid 1
, set the Material to
N2 Ideal Gas
(note: use the icon) 3.
4.
Switch to the
Fluid Models
tab Set
Heat Transfer
to
Isothermal
5.
Set
Fluid Temperature
to
450 [C]
6.
Set
Turbulence
to
k-epsilon
7.
Click
OK Workshop Supplement
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WS4-5 April 28, 2009 Inventory #002599
WS4: Flow Through Porous Media
Setting Up Boundary conditions
2.
3.
4.
5.
1.
6.
7.
8.
9.
Insert a boundary condition named
Inlet
Set
Boundary Type
to
Inlet
Set
Location
to
INLET
Switch to the
Boundary Details
tab Set
Mass and Momentum
to a
Normal Speed
of 10 [m s^-1] Click
OK
Insert a Boundary Condition named
Outlet
Set
Boundary Type
to
Outlet
Set
Location
to
OUTLET
10.
Switch to the
Boundary Details
tab 11.
Enter a
Relative Pressure
of 0 [Pa] 12.
Click OK ANSYS, Inc. Proprietary © 2009 ANSYS, Inc. All rights reserved.
WS4-6
Workshop Supplement
April 28, 2009 Inventory #002599
WS4: Flow Through Porous Media
Setting Up Porous Domain
2.
3.
4.
5.
6.
1.
Right-click on
Flow Analysis 1
and insert a Domain named
Substrate
Set the
Location
to SUBSTRATE Set the
Domain Type
to
Porous Domain
Switch to the
Porosity Settings
tab Set
Volume Porosity
to
0.5
Set the
Loss Mod
el option to
Directional Loss
7.
8.
For the
Streamwise Direction
, enter components of
0,0,1
Set
Streamwise Loss
to
Linear and Quadratic Resistance Coefficients
9.
Turn on
Quadratic Resistance Coefficient
and enter a value of
440 [kg m^-4]
10.
Set the
Streamwise Coefficient Multiplier
to
100
and click
OK
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WS4-7
Workshop Supplement
April 28, 2009 Inventory #002599
WS4: Flow Through Porous Media
Domain Interface
CFX automatically creates a Fluid-Porous interface between the Default Domain and Substrate.
You can double-click
Default Fluid Porous Interface
to view the setup, or highlight the
Default Fluid Porous Interface Side 1
and
Default Fluid Porous Interface Side 2 boundaries
in the individual domains to see that that regions are correct.
ANSYS, Inc. Proprietary © 2009 ANSYS, Inc. All rights reserved.
WS4-8
Workshop Supplement
April 28, 2009 Inventory #002599
WS4: Flow Through Porous Media
Output Control
Workshop Supplement
1.
2.
3.
4.
5.
6.
Edit
Output Control
from the Outline tree Switch to the
Monitor
tab and turn on
Monitor Options
Click to create a new monitor object, and call it
Mass Flow at Outlet
Set the
Option
to
Expression
Set the
Expression Value
to
massFlow()@Outlet
Insert a new object in the same way called
Pressure Drop
, using the
Expression
:
Right-click
massFlowAve(Total Pressure)@REGION:INLETSUBSTRATEINTERFACE_1 massFlowAve(Total Pressure)@REGION:OUTLETSUBSTRATEINTERFACE_1
7.
Click
OK
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WS4-9 April 28, 2009 Inventory #002599
WS4: Flow Through Porous Media
Starting Solver
1.
2.
3.
Close CFX-Pre and save the project Double-click
Solution
to start the Solver Manager When the Solver Manager opens click
Start Run Workshop Supplement
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4.
At the end of the run, click the
User Points
tab and click the green line where it flattens out. It reports a pressure drop value of approx 285 Pa across the substrate WS4-10 April 28, 2009 Inventory #002599
WS4: Flow Through Porous Media
Post-processing
1.
2.
3.
4.
5.
When the solver finishes, close the Solver Manager Double-click on
Results
in the Project page to start CFD-Post Once CFD-Post is open, select
Location > Plane
from the toolbar Set Set
Method Y
to to 0 [m]
ZX Plane
6.
7.
Click
Apply
Turn off Visibility for Plane 1 by disabling the check-box next to its entry in the Outline tree 8.
9.
Select
Insert > Vector
Select
Locations
10.
Click
Apply
to
Plane 1
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WS4-11
Workshop Supplement
April 28, 2009 Inventory #002599
WS4: Flow Through Porous Media
Post-processing
1.
2.
3.
4.
5.
Hide the Vector plot created in the last step Select
Insert > Contour
Set
Locations
to
Plane 1
Set
Variable
to
Pressure
Click
Apply Workshop Supplement
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WS4-12 April 28, 2009 Inventory #002599
WS4: Flow Through Porous Media
Post-processing
2.
3.
4.
5.
6.
1.
Select
Location > Line
from the toolbar Set
Point 1
to
0,0,-0.07
Set
Point 2
to
0,0,0.07
Click
Apply
Select
Insert > Chart
On the
General
tab enter
Pressure in Porous Domain
as the
Title
7.
8.
9.
On the
Data Series
tab, click to create Series 1 Set
Location
to
Line 1
On the
X Axis
tab, set
Variable
to
Z
10.
On the
Y Axis Pressure
tab, set
Variable
to 11.
Click
Apply
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WS4-13
Workshop Supplement
April 28, 2009 Inventory #002599
WS4: Flow Through Porous Media
Post-processing
1.
2.
3.
Switch to the
Expressions
tab Right-click and select
New
Enter the
Name
as
deltaP
and enter the
Definition
as: massFlowAve(Total Pressure)@Inlet massFlowAve(Total Pressure)@Outlet 4.
Click
Apply
to evaluate the expression The value should come out to be approximately 300 Pa. Since we know from the solver monitor value that approx. 285 Pa or Total Pressure is lost across the substrate, we can determine that 15 Pa is lost through the rest of the device.
ANSYS, Inc. Proprietary © 2009 ANSYS, Inc. All rights reserved.
WS4-14
Workshop Supplement
April 28, 2009 Inventory #002599