Cfd & fluent (k-e turb.model and mesh)

In summary, The speaker is seeking help with creating a mesh for an airfoil to be used with FLUENT. They must use the k-e turbulent model and ensure that the Y plus of the first cell is within 30-300 for standard wall function. They are unsure of how to compute the Y length of cells for the mesh and ask for guidance on the process. The listener suggests using the Sheared Parabolic Grid Generation technique, which involves creating a cartesian grid and transforming it to fit the airfoil shape. They also recommend using a Joukowski Airfoil for testing, as it has analytic solutions that can be used for validation.
  • #1
mech5190
1
0
Hi. I want to make a mesh for a airfoil for i solute it with FLUENT.
I must use the k-e turbulent model but i do not know how i make the mesh near the wall of airfoil. I have read that the Y plus of first cell must be within 30-300 for standard wall function.
However, How can i compute the Y length of cells for i make the mesh arround the foil?
Is there a specific prosses for the constraction of mesh?
 
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  • #2
Do a search for "Sheared Parabolic Grid Generation". This is a common analytic grid generation technique. In fact...I think I've posted the method on here some while back.

The idea is that you create a cartesian grid, then "wrap" it around the airfoil using complex transforms. This will give you the best possible grid for solving an airfoil.

Might I also suggest using a "Joukowski" Airfoil to test with. This is an analytically generated airfoil shape (once again using complex transforms). Because it's an analytic shape, analytic solutions exist that you can validate against.
 

1. What is CFD and how is it used in engineering?

CFD stands for Computational Fluid Dynamics. It is a branch of fluid mechanics that uses numerical analysis and algorithms to solve and analyze problems involving fluid flow and heat transfer. In engineering, CFD is used to simulate and predict the behavior of fluids and their interactions with solid surfaces, allowing for the design and optimization of various systems such as airplanes, cars, and turbines.

2. What is the k-e turbulence model in CFD?

The k-e turbulence model is a semi-empirical model used in CFD to represent the turbulent flow in a fluid. It uses two variables, k and e, to represent the kinetic energy and dissipation rate of turbulence. This model is commonly used for both industrial and research applications due to its relative simplicity and accuracy in predicting turbulent flows.

3. How is the k-e turbulence model different from other turbulence models?

The k-e model is a two-equation model, meaning it uses two equations to represent the flow field. Other turbulence models, such as the k-ω and Reynolds Stress models, use more equations and are typically more complex. The k-e model is also isotropic, meaning it assumes the turbulence is the same in all directions, whereas some other models account for anisotropy.

4. What is meshing in CFD and why is it important?

Meshing is the process of dividing a computational domain into smaller elements, such as triangles or tetrahedrons, to create a grid for numerical calculations in CFD. The quality of the mesh can greatly affect the accuracy and convergence of the simulation results. A well-structured and refined mesh is important for accurately capturing the complex flow phenomena in a system.

5. How can I validate the results of a CFD simulation using Fluent?

Fluent, a popular CFD software, offers several methods for validating simulation results. This can include comparing the simulation results to experimental data, verifying the convergence of the solution, and running sensitivity analyses to assess the effects of changing certain parameters. It is important to validate CFD results to ensure the accuracy and reliability of the simulation.

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