Simulating two different porosity sections, such as a screen and a honeycomb, in a single CFD model using Ansys Fluent involves setting up the model to account for the distinct porosity characteristics of each section. Here’s a step-by-step guide to achieve this:

1. Geometry Preparation

• Create a 3D geometry in Ansys DesignModeler or any CAD software that includes both the screen and honeycomb sections.
• Ensure the geometry is properly segmented so that the screen and honeycomb regions are distinct and can be assigned different properties.

2. Mesh Generation

• Generate a mesh in Ansys Meshing or another meshing tool.
• Ensure the mesh is fine enough to capture the flow characteristics near the screen and honeycomb regions.
• Use appropriate mesh controls to refine the mesh in areas where high gradients are expected (e.g., near the screen and honeycomb).

3. Define Porosity Regions

• In Ansys Fluent, you can model porosity using the Porous Media model.
• Create two separate fluid zones in the geometry: one for the screen and one for the honeycomb.
• Assign each zone its respective porosity properties.

4. Set Up Porous Media Model

• In Fluent, go to the Cell Zone Conditions panel.
• For each zone (screen and honeycomb), enable the Porous Zone option.
• Define the porosity parameters for each zone: Screen: Typically modeled as a thin porous medium with a high pressure drop coefficient. Use the Darcy-Forchheimer equation to define the resistance coefficients (viscous and inertial resistance). Honeycomb: Modeled as a porous medium with a lower pressure drop compared to the screen. Define its resistance coefficients based on its geometry and flow characteristics.

5. Input Porosity Parameters

• For the screen: Viscous resistance: α1​ (where αα is the permeability). Inertial resistance: C2​ (inertial resistance coefficient).
• For the honeycomb: Use similar parameters but adjusted for the honeycomb’s specific geometry and flow resistance.
• These parameters can be derived from experimental data, empirical correlations, or literature.

6. Boundary Conditions

• Set appropriate boundary conditions for the inlet, outlet, and walls.
• Ensure the flow direction is aligned with the orientation of the screen and honeycomb.

7. Solver Settings

• Choose a suitable solver (pressure-based or density-based) depending on your flow regime.
• Select a turbulence model (e.g., k-ε or k-ω) if the flow is turbulent.
• Initialize the solution and run the simulation.

8. Post-Processing

• Analyze the results to observe the flow behavior through the screen and honeycomb sections.
• Check pressure drop, velocity profiles, and other relevant parameters to ensure the simulation captures the combined effect of the two porosity regions.

Notes:

• If the screen and honeycomb are very thin, you may need to model them as 2D surfaces with porous jump boundary conditions instead of 3D porous zones.
• Validate your results with experimental data or analytical solutions to ensure accuracy.

By following these steps, you can effectively simulate the combined effect of a screen and honeycomb on a flow in Ansys Fluent.

Divide the CAD model into sections and apply the necessary boundary conditions, each section will have its own porosity

You just need to create different cell zones. The in cell zone conditions you can define them as Porous zone separately.