Species transport
Mixing in duct
Introduction
This is an example of an transient chemical species mixing. A two-dimensional duct with two openings is introduced with air at the top opening and water vapor at the bottom opening.
The simulation conditions are as follows
- solver : buoyantPimpleNFoam
- turbulence model : \(Standard\) \(k-\epsilon\) model
- flow condition : 0.5 \(m/s\) at inlet
Start BaramFlow and load mesh
Run the program and select [New Case] from the launcher. In the launcher, select [Pressure-based] for [Solver Type] and [None] for [Multiphase Model].
Use the given polyMesh folder. In the top tab, click [File]-[Load Mesh]-[OpenFOAM] in that order and select the polyMesh folder.
General
Change Time to Transient.
Set Gravity as (0 -9.81 0).
(Models
Double click Species and select [Include].
Materials
Click the (+) in the top right corner of the Materials panel to add a mixture. Select air and waterVapor as shown on the left in the image below and click 'Create Mixture' to create a mixture as shown on the right.
Cell zone Conditions
Double-click region0 in Cell Zone Conditions and change the Material to mixture.
Boundary Conditions
Set the boundary type and values as shown below.
- in-up : Velocity Inlet
- Velocity Specification Method : Magnitudde, Normal to Boundary
- Velocity Magnitude : 0.5 (m/s)
- Turbulent Intensity : 0.1 (%)
- Turbulent Viscosity Ratio : 1
- mixture - air : 1
- mixture - waterVapor : 0
- Temperature : 300
- in-down : Velocity Inlet
- Velocity Specification Method : Magnitudde, Normal to Boundary
- Velocity Magnitude : 0.5 (m/s)
- Turbulent Intensity : 0.1 (%)
- Turbulent Viscosity Ratio : 1
- mixture - air : 0
- mixture - waterVapor : 1
- Temperature : 300
-
out : Pressure Outlet
- Pressure : 0 (Pa)
-
down_surface, up : wall
- noSlip
-
zMin, zMax : empty
Numerical Conditions
In this example, we'll change the settings as shown below.
-
Pressure-Velocity Coupling Scheme : SIMPLE
-
Discretization Scheme
- Time : Second Order Implicit
- Pressure : Linear
- Momentum : Second Order Upwind
- Turbulence : Second Order Upwind
- Species : Second Order Upwind
-
Under-Relaxation Factors
- Pressure : 0.3
- Momentum : 0.7
- Turbulence : 0.7
- Species : 1
-
Convergence Criteria : use default values
-
Max Iterations per Time Step : 100
-
Number of Correctors : 2
Initialization
In this example, we'll change the settings as shown below.
- Velocity : (0.5 0 0)
- Pressure : 0
- Scale of Velocity : 0.5
- Turbulent intensity : 0.1
- Turbulent viscosity ratio : 1
- mixture - air : 1
- mixture - waterVapor : 0
Enter the value and click the Initialize button at the bottom. Then click the [File]-[Save] menu to save the case file.
Run
Change the values as shown below, and click [Start Calculation] button.
- Time Stepping Method : Fixed
- Time Step Size : 0.001
- End Time : 20
- Save Interval : 0.1
Post-processing
Click the parview button in [External tools] to open the paraview.
Change [Coloring] to [waterVapor].
