1. Introduction
In this tutorial, we will explore the process of cooling a steel cylinder using a stream of water. You will learn how to create a multi-region mesh, using a 2D mesh for simplification. This problem involves solving the interaction between a solid and a fluid as a conjugate heat transfer (CHT). As a result, we will track the temperature fields for both the cylinder and the fluid over time.
2. Download SimFlow
SimFlow is a general purpose CFD Software
To follow this tutorial, you will need SimFlow free version, you may download it via the following link:
Download SimFlow
3. Create Case
Open SimFlow and create a new case named cylinder_cooling
- Go to New panel
- Provide name cylinder_cooling
- Click Create Case

4. Create Geometry - Cylinder
We need to create a cylindrical boundary for the domain. For this purpose, we will create a cylindrical geometry for later use in the meshing process.
- Go to Geometry panel
- Select Create Cylinder
- 4 Define origin, length, and radius of the cylinder accordingly
Origin \({\sf [m]}\)00-0.25
Length \({\sf [m]}\)0.5
Radius \({\sf [m]}\)0.05

5. Geometry - Cylinder
After creating a cylindrical boundary, it will appear in the 3D panel.
- Click Fit View to zoom the geometry

6. Meshing Properties - Cylinder
- Go to Hex Meshing panel
- Click cylinder_1
- Select Mesh Geometry
- Select Create Boundary Layer Mesh

7. Base Mesh - Geometry and Mesh
We will define the base mesh now.
- Go to the Base tab
- Chose Plate Mesh Type
- Define base mesh minimum and maximum extend
Min \({\sf [m]}\)-1-0.4
Max \({\sf [m]}\)10.4 - Define division along each axis
Division200 80

8. Base Mesh - Boundaries
- Define boundary names accordingly
X- inlet
X+ outlet - Define the following boundary types accordingly
Y- wall
Y+ wall

9. Material Point - Fluid
Now we will define material point outside the cylinder geometry.
- Go to Point tab
- Set location of the material point
Material Point00.20

10. Meshing - Fluid Region
- Go to Mesh tab
- Start the meshing process with Mesh button

11. Mesh - Fluid Region
After a few minutes of meshing the following mesh should appear.
- Click Fit View to zoom the geometry
- Click View XY to orient view plane

12. Create Sub-Region - Fluid
After creating the mesh, we have to make a sub-region - fluid.
- Go to Mesh panel
- Press Options button
- Select Make sub-region option
- Enter name fluid for the sub-region
- Click OK button

13. Material Point - Solid
Now we will define material point for sub-region - solid.
- Go to Hex Meshing panel
- Go to Point tab
- Set location of the material point
Material Point000

14. Meshing - Solid Region
Everything is set up now for the meshing of the solid region
- Go to Mesh tab
- Start the meshing process with Mesh button

15. Mesh - Solid Region
After a few minutes of meshing the following mesh should appear.
- Click Fit View to zoom the geometry

16. Create Sub-Region - Solid
After creating the mesh, we have to make a sub-region - solid.
- Go to Mesh panel
- Press Options button
- Select Make sub-region option
- Enter name solid for the sub-region
- Click OK button

17. Create Region Interface
Two mesh regions are not coupled until you create a region interface. It will be further used to define which information is exchanged between regions.
- Select Solid type for solid region
- Make sure you have selected wall type for cylinder_1
- Hold CTRL key and select cylinder_1 in fluid and cylinder_1 in solid
- Click Create Region Interface icon

18. Select Solver - CHT Multi Region
- Go to Setup panel
- Select Transient filter
- Select Heat Transfer model filter
- Pick CHT Multi Region
- Select solver

19. Thermophysical Properties - Fluid (I)
We will define now the thermodynamic properties of fluid material.
- Go to Thermo panel
- Select fluid region
- Select Constant Density
- Click Material Database button

20. Thermophysical Properties - Fluid (II)
- Select water material
- Click Apply

21. Thermophysical Properties - Solid (I)
We will define now the thermodynamic properties of solid material.
- Select solid region
- Select Constant Density
- Click Material Database button

22. Thermophysical Properties - Solid (II)
- Select steel material
- Click Apply

23. Solution - Solvers
- Go to Solution panel
- Go to the Pimple tab
- Increase the number of Correctors to 2

24. Operating Conditions
- Go to Operating Conditions panel
- Define gravitational acceleration
g \({\sf [m/s^2]}\)0-9.810

25. Boundary Conditions - Inlet (Flow)
- Go to Boundary Conditions panel
- Select inlet
- Change character to velocity inlet
- Define inlet velocity
Reference Value \({\sf [m/s]}\)0.1

26. Boundary Conditions - Inlet (Thermal)
- Go to Thermal boundary conditions tab
- Set the following parameters accordingly
TypeFixed Value
Value \({\sf [K]}\)300

27. Initial Conditions
- Go to Initial Conditions panel
- Select solid region
- Set temperature T to 400

28. Run -Time Control
- Go to Run panel
- Set Simulation Time [s] to 200
- Change Time Stepping to Automatic
- Set initial and maximum time step accordingly
Initial \(\Delta t\) \({\sf [s]}\)0.2
Max \(\Delta t\) \({\sf [s]}\)0.2

29. Run - Output
- Switch to Output panel
- Set Write Control Interval [s] to 5

30. Run - CPU
To speed up the calculation process increase the number of CPUs basing on your PC capability. The free version allows you to use only 2 processors in parallel mode. To get the full version, you can use the contact form to Request 30-day Trial
Estimated computation time for 2 processors: 3 minutes
- Switch to CPU tab
- Use parallel mode
- Increase the Number of processors
- Click Run Simulation button

31. Residuals

32. Start Postprocessing with ParaView
- Go to Postprocessing panel
- Run ParaView

33. ParaView - Load Results
Now we are loading results into the ParaView.
- Select cylinder_cooling.foam
- Click Apply to load results into ParaView
- After loading results they will be shown in the 3D graphic window

34. ParaView - Change Background
We can change the coloring scheme in ParaView to have nicer colors.
- Click Load a Color Palette
- Select White Background

35. ParaView - Choose Preset (I)
- Click Edit Color Map from the menu placed on the left side, if the panel is not already shown.

36. ParaView - Choose Preset (II)
- Select Choose Preset from the Color Map Editor placed by default on the right side of the ParaView
- Search rainbow
- Choose Blue to Red Rainbow preset.
- Apply changes
- Close Choose Preset window
- Set Number of Table Values to 20
- Click Save current color map settings values as default for all arrays

37. ParaView - Display Temperature Contour (I)
- Select contour coloring variable to T
- Click Last Frame
- Click Rescale to Data Range
- Click First Frame
- Click Play

38. ParaView - Display Temperature Contour (II)
After applying changes the contour will be shown in the 3D window.

39. ParaView - Display Temperature Contour (III)
- Click First Frame
- Click Rescale to Custom Data Range
- Set maximum value
Max305 - Click Rescale
- Click Play

40. ParaView - Results
