11 / 9 / 2025
3 mins tutorial: Prepare CFD cases in nTOP with connector
Introduction
This tutorial provides a step-by-step workflow for CFD analysis, covering geometry modeling, meshing, boundary condition setup, CFD export, e.g. to Fluent..
Modeling
Solid
Coolant Fluid
Air Fluid
Mesh
Step 1: Open the Chop Mesh function
Expand the Connector component in the toolbar.Locate the ChopMesh icon under this component and click it to activate.
ChopMesh Component Functions
Boday: Drag the Implicit Body geometry into this field to define the target volume for meshing.
number of nx:
refinement level: Specifies the Level of refinement, which controls the number of refinement layers—the higher the value, the finer the mesh.
Mesh Generation Settings
Parameterized. meshing: The Air_Fluid domain was defined with parameterized inputs for number of nx and refinement level. This allows flexible adjustment of mesh resolution under different test conditions, which is useful for parametric studies and sensitivity analysis.
Non-parameterized meshing: The Solid and Coolant_Fluid components were assigned fixed values of number of nx and refinement level.
Refinement Demonstration
Higher resolution in critical regions improves accuracy.
Coarser mesh in less important regions reduces the overall cell count, saving computational reesources.
Provides a good balance between accuracy and efficiency.
30-3
40-3
50-3
Boundary Condition
When defining the boundary conditions of an FE Mesh, there are multiple ways to select boundaries. Three commonly used methods are:
How to select boundaries of an FE Mesh - FE Boundary by Flood Fill
How to select boundaries using Boundary by Boday
How to create CFD Boundaries
These links provide detailed step-bystep instructions for selecting mesh boundaries, which can then assigned to appropriate vondary conditions.
Export FE Mesh to CFD
After defining the boundary conditions, the nect step is to export the FE mesh to the CFD module.
Path: Specify the file path for exporting the mesh.
Mesh: Select the FE Mesh to be exported.
Units: Define the units for the exported mesh.
Boundaries: Assign the previously defined boundary conditions.
Wall Name: Optional field to define wall names for easier identification in CFD simulations.
CFD
After exporting the FE mesh, the next step is to importt it into CFD. The basic procedure is as follows:
Launch CFD software and gp to File → Read → Mesh to import the mesh file exported from nTop.
Once the mesh is loaded, check the grid information(cell count, node count, zones, etc.) to ensure integrity.
Note: Any faces that were not explicitly assigned boundary conditions in nTopology will be automatically recognized as Wall. These should be reviewed and modified if necessary according to the physical setup.
Mesh interface setup
In CFD setup, it is necessary to couple the solid and fluid regions through meshh interfaces. The procedure is:
Open the Mesh Interfaces panel.
Select the fluid-side wall and the solid-side wall.
Click the Create button at the bottom of the panel
CFD solver will automatically perform the Mapping, generating a coupled solid-fluid interface.
At this point, the solid and fluid boundaries are successfully matched, ensuring correct tranfer of heat and flow across the interface.
CFD setup
After importing the mesh and creating the mesh interfaces, the following physical settings were defined:
Materials:
Coolant: Water
Cooling medium: Air
Solid: Aluminum
Boundary Conditions:
Air inlet: 10 m/s
Coolant inlet: 1 m/s
Outlet: Pressure outlet
Energy Equation: ON
Results
Solid of temperature
Fluid of pressure
Temperature
