Case Catalog
1 intro
1.1 Case Description
1.2 Case study Goals
2 Calculating simulation targets
3 start fluent and read the grid
4 Fluent Working interface
5 Grid scaling and checking
6 modifying units
7 Setting up the model
8 Defining new Materials
9 Computing Domain settings
10 Boundary condition Settings
12 Setting discrete formats
Monitors
Initialization
Run calculation
Results
16.1 Calculation and monitoring graphics
16.2 Graphics
Temperature distribution of 16.2.1 wall surface
16.2.2 Creating a section
16.2.3 display of cross-sectional physical quantities
16.2.4 pathline Display
16.3 plots
1 Intro 1.1 Case Description
In this case, the flow simulation in T-tube is carried out, the fluid enters T-tube at different temperatures, and the mixing process is simulated by calculation.
1.2 Case study Goals
This case mainly describes the use of the fluent interface, including the entire process of CFD, including:
- Read grid
- Select a calculation model
- Select and set material properties
- Defining boundary conditions
- Setting up the calculation monitor
- Run the Solver
- Post-processing
2 Calculating simulation targets
The simulated object is the mixing process of hot and cold water in T-tube.
The purpose of computational simulation is to determine:
- 1. Fluid Mixing Degree
- 2. Pressure drop in the mixing process
3 start fluent and read the grid
This case takes advantage of the fluent module in Workbench and can also be done using a standalone version of fluent.
- 1. Start Workbench, using the menu Files | Save as ... Save a new file Mixing_tee
- 2. From the Component Systems list on the left, select drag Fluent to the right of the project window
- 3. Right-click cell Setup, select submenu Import FLUENT Case | Browse
- 4. In the Open File Selection dialog box, modify the file filtering options for the Fluent Mesh file
- 5. Select the grid file Mixing_tee.msh, click the OK button to confirm the selection
As shown in.
- 6. Return to the project panel, mouse double-click on the Setup cell to start fluent, as shown, you can choose serial or parallel computing based on your computer's performance (as shown in parallel 4-core calculations)
- 7. Click the OK button to enter the fluent working environment
4 Fluent Working interface
FLUENT17.0 work interface. It consists of 5 main parts:
- 1.Ribbon menu. It contains all the action buttons.
- 2. Model Tree. Contains all the required nodes in the CFD simulation process
- 3. Parameter Settings panel. parameter settings that correspond to the different model tree nodes
- 4. Graphical display window.
- 5.TUI and Message Output window
5 Grid scaling and checking
After importing the calculation grid, the first step is to check the imported grid validity and grid quality.
- Select and model tree node General
- Click on the button in the right panel to CheckThe feedback information as shown in the Tui window.
Note: The main check two parameters: one is domain extents, to see whether the calculated domain size matches the actual size, if not match the calculation field needs to be scaled, and the other is mimimum volume, you must ensure that the minimum volume is greater than 0
- 2. Select the report quality button in the panel to view the grid quality. The TUI Command window shows the grid quality as shown.
Three grid qualities are given: Minimum orthogonal quality, Maximum Ortho Skew and Maximum Aspect Ratio, where Minimum orthogonal The range of the quality is 0-1 (1 is the ideal mesh), the Maximum Ortho skew range is 0-1 (0 is the ideal grid), and the Maximum Aspect ratio the smaller the better.
6 modifying units
The temperature is modified in degrees Celsius. Click Units in the General Settings panel ... The button pops up the Unit settings panel.
As shown, set the temperature unit to C.
7 Setting up the model
This activates the energy equation and turbulence model.
- Double-click the Model tree node Models >Energy, and in the Power-up dialog box, tick the checkbox in front of equation to activate the equation as shown. Click the OK button to confirm the operation.
- Double-click the Model tree node Models > Viscous (Laminar), select K-epsilon (2 eqn)in the popup dialog box,realizable, other parameters remain default, click OK button to confirm the operation.
8 Defining new Materials
Fluent by default, the material is air, in case the fluid medium is liquid water.
- Right click on the Model tree node Material > Fluid, select the popup menu New, as shown in.
- In the dialog box that pops up, select Fluent database..., pop up the Material Library dialog box, select Material water-liquid (H2O ) in the material library, and click copy< /c14> button and click the Close button to close the dialog box as shown in.
Click The Close button to close the Material New dialog box.
9 Computing Domain settings
- Mouse double-click model tree node Cell zone Conditions > Fluid (fluid), popup parameter Settings panel, set Material Name in the parameters panel for the material created in the previous step Water-liquid, as shown in.
- Click the OK button to close the dialog box.
10 Boundary condition Settings
You can set the boundary conditions for the calculation model in the Model tree node boundary Conditions ...
Interface elements are similar to the cell Zone conditions Setup Panel.
Set Boundary conditions:
- inlet-y Boundary settings
- Select the boundary inlet-yin the Zone list box, select the Type drop-down box option velocity-inlet, click the mouse button to Edit ...
- The Parameter Settings dialog box pops up. Under the Momentum tab, set the Velocity manitude parameter value to 0.3; Select specification Method to Intensity and hydraulic Diameter, set tubulent Intensity to 5, set hydraulic Diameter For 0.15.
- Switch to the Thermal panel and set temperature to.
- inlet-z Boundary settings
- Similar to the inlet-y setting, the difference is that the Velocity manitude parameter value is set to 0.1, and the hydraulic Diameter is set to 0.1; set temperature to
- Outlet boundary settings
- Select the Type drop-down box option pressure-outlet, click Edit ... Button
- In the popup dialog box Momentum tab, set Gauge pressure to 0, set specification Method to Intensity and hydraulic Diameter, set backflow turbulent Intensity to 5, set backflow hydraulic Diameter to 0.15
- Switch to the Thermal panel and set temperature .
It is important to note that in the process of calculation, it is possible for the media to enter the fluid domain from the exit boundary (reflux), which may be true flow characteristics (reflux is still present in the calculation of convergence), or simply a transient state during the convergence process (the reflux disappears with the calculation). In any case, fluent needs to know the real flow of information on the boundary. If there is no reflux at the outlet location, these reflux parameter values will not be used during the calculation process. When you select a calculated boundary position, the exit position is usually selected where there is no reflow.
12 Setting discrete formats
The Model tree node solution Methods the discrete algorithm of the main setting model.
- Choose pressure-velocity Coupling scheme for coupled
- Activation Options Pseudo Transient
- Activation Options warped-face Gradient Correction
The discrete format defines the calculation method of gradient and variable interpolation. The default options apply to most computing issues.
Monitors
The Model tree node Monitors can be used to monitor the changes of some physical quantities during the calculation. This example sets the monitoring of two inlet pressure values and the outlet temperature standard deviation. The Monitors Setup Panel looks like this.
Set some parameters in the panel:
- residuals,statisticand force Monitors: monitoring residuals, statistical values, and various forces
- surface Monitors: Various parameter values on the monitoring surface
- Volume Monitors: Various parameter values on the monitoring body
- covergence Monitors: Convergence monitoring, through the preceding monitoring parameters to determine whether the calculation convergence
In this example, three polygon parameters are monitored and created using the Create button below surface Monitors . The mouse selects this button as shown in.
Define three monitors, steps include:
Click Create under Surface Monitors ... Button
- Name: Set to p-inlet-y
- Plot Windws: Set to 2
- Report Type: Set to area-weighted Average
- Field Variable: Set to pressure and Static pressure
- Surface: Select inlet-y
Click Create under Surface Monitors ... Button
- Name: Set to p-inlet-z
- Plot Windws: Set to 3
- Report Type: Set to area-weighted Average
- Field Variable: Set to pressure and Static pressure
- Surface: Select inlet-z
Click Create under Surface Monitors ... Button
- Name: Set to T-dev-outlet
- Plot Windws: Set to 4
- Report Type: set to standard Deviation
- Field Variable: Set to temperature and Static temperature
- Surface: select outlet
Initialization
The compute domain can be initialized using the Model tree node solution initialization . Fluent provides two types of initialization methods:
- Hybird Initialization: The initial values in the computed domain are obtained by various interpolation methods. How to obtain the initial velocity field and the pressure field by solving the Laplace equation
- Standard Initialization: Defines the initial value of each unknown physical quantity directly
This case is initialized with the Hybird initialization method, as shown in, select the Initialize button to initialize. The warning message may appear in the graphics window as shown, but this is only a hint that the Laplace equation is not convergent and can be ignored.
For steady-state calculations, the initial value does not affect the final calculation, but it affects the convergence process, and a serious deviation from the actual initial value may cause the computation to converge slowly or even diverge. For transient calculations, the initial value affects the subsequent calculation results.
Run calculation
Select the Model tree node Run calculation.
- Set number of iterations to Calculate, click the button Calculate to iterate.
Results
Post-calculation processing.
16.1 Calculation and monitoring graphics
Residual curve
The residual curve as shown in the calculated monitoring.
The residual curve shows that the calculation is convergent around 120 steps in the iteration, showing that the residual curve is reduced below the set residual standard, and the default residuals standard is ten? 3 ten ? 3
Inlet pressure monitoring diagram
Two inlet pressure monitoring diagram as shown.
(Fig. 1)
(Fig. 2)
From these two pressure monitoring graphs, the calculation results are basically stable, and the pressure values change very little with iteration.
- Outlet temperature Standard deviation Change Chart
The output temperature standard deviation curve as shown in the monitoring.
The temperature standard deviation reflects the uniformity of the temperature mixture, the larger the value indicates the more uneven temperature distribution. The final temperature standard deviation in the figure is about 0.2.
16.2 Graphics
The Model tree node Graphics contain Mesh,contours,Vectors,pathlines , and Particle Tracks,. The graphics parameter settings panel also contains animations actions and some graphical display parameter settings buttons, such as lights, views, and so on.
- mesh: Show grid diagram
- contours: Display cloud
- Vectors: displaying vector images
- pathlines: Display Streamline diagram
- particle Tracks: Show particle tracking graph
This case mainly uses contours and Vectors to display cloud images and vectors.
Temperature distribution of 16.2.1 wall surface
View wall temperature cloud display. The mouse double-clicks the contours list item in the Graphics list box and makes the settings as shown in the popup dialog box:
- Tick the Activate Filled option
- Select temperature and Static temperature in the contours of drop-down box
- Select wall-fluid in the surfaces list item
- Click the button Display
The temperature cloud image on the wall is displayed as shown.
16.2.2 Creating a section
After you create a section, you can display the physical quantity distribution on the section. The x section is created here.
- Using the postprocessing tab in the Ribbon interface
- Select iso-surface under the Create button ... Function Menu
As shown in.
In the dialog box that pops up:
- Choose Surface of Constant for Mesh and x-coordinate
- Set iso-value to 0
- Set New Surface Name to x-0
- Click The Create button to make a section
16.2.3 display of cross-sectional physical quantities
Back to the contours Setup Panel,
- Set contours of velocity and velocity Magnitude
- Choose Surface as x-0
- Click the button Display
Show the speed cloud as shown.
Set contours of temperature and Static temperature, click the Display button.
Display the temperature cloud as shown in.
16.2.4 pathline Display
Streamline can be displayed using pathline . Select the pathlines option in the Graphics list, which pops up as shown in the dialog box.
The streamline diagram shown is shown.
16.3 plots
The Model tree node plots can output a series of graphs, such as graphs, histograms, and so on.
List items:
- XY plot: Show the change pattern of variables in XY graph
- histogram: Displaying data in histogram form
- file: Displaying data in a document in a graphical form
- Profile: Graphical display of configuration files
- FFT: A fast Fourier transform of the data specified by the file, converting time-domain data into frequency domain data.
You can create lines first, and then use Xyplot to display the physical distribution on the line. Using the postprocessing tool button Create, select menu item line/rake... as shown in.
The dialog box pops up as shown:
- Set Type to line
- Set End point distribution to * * (0,-0.3556,0) and (0,0.3556,0)
- Set New Surface Name to line-center
Double-click the Model tree node XY Plot, which pops up as shown in the dialog box, with the following settings:
- Set Plot Direction to * * (0,1,0)
- Set Y Axis Function to velocity and velocity Magnitude
- Select Surface list item line-center
- Click the button Plot
Displays the velocity distribution curve along the line Line-center as shown in.
From for notes (Wiz)
"Fluent case" flow and heat transfer in 01:t type pipe mixer
