Physics Setup

Launch Fluent

To launch FLUENT, double click Setup under Project Schematic.

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You can leave the rest as Default. Select Parallel if desired. Now press OK to launch FLUENT.

Check Mesh

It is always a good practice to check mesh, specially if you are importing mesh that wasn't created by you. It is not rare to get matching errors, particularly when meshes with multiple Cell-Zones like our case.

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Lastly, you can type "mesh/check" and hit Enter in the messages box.

Create mesh interfaces

As briefly discussed, we need to start by creating the interfaces between the different zones of mesh.

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By the end of this step, your window should look like this.

Set Solver informations

Now, resuming...

Select the first option under "Setup": "General".

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Lastly, click in "Units" and change the "angular-velocity" unit to rpm.

Set the Model

Here is where we tell FLUENT all simplifications for the model it can assume. For instance, here you specify if the model is Inviscid, Laminar or Turbulent, if you should consider the Energy Equation (for supersonic flows), and other options.

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Highlight "Model" and double click the third item in the list, "Viscous - Laminar". Select "k-epsilon (2 eqn)". Change "k-epsilon Model" to Realizable. Retain the rest as default. Click Ok.

Materials

We will use the default properties for air. Go ahead and check if they are correct.

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Viscosity: 1.7894e-05 kg/m-s

Cell Zone Conditions

Here we specify to fluent the material of each meshed zone (usually correct by default, unless we create a new material).

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These are the same zones described previously, when creating the mesh interfaces. We will have to edit parameters for each of them.

fluid-surface_body

Highlight fluid-surface_body and click "Edit...".

No options should be selected here, and the material must be set to air. This is the default. You can verify that and click Ok.

inner

Highlight inner and click "Edit...". Here we will set that the inner portion of the hub is spinning, adding more terms to the equations to account for local acceleration, even though the mesh is not actually moving.

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The rest you can keep as default. Click Ok.

blades

Highlight blade_top and click "Edit...". 

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We are now ready to set the other boundary conditions!

Boundary Conditions

Remember that we had already set some Boundary Conditions, before doing the Mesh Interfaces. However we still need to tell FLUENT what is wall, and specify some pressures and velocities.

Velocity at the inlet

First, specify the velocity at the inlet.

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Under "Turbulence", change the "Specification Method" to "Intensity and Length Scale". Set the "Turbulence Intensity (%)" to 5 and the "Turbulent Length Scale (m)" to 1.

Pressure at the outlet

Locate and highlight "farfield2". Change its Type to "pressure-outlet".

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Note: is this window does not automatically pop up, click "Edit...", next to where you specified the Type of the boundary condition.

Wall

We need to tell FLUENT that the blades of the turbine are walls (i.e., no-slip condition, or no velocity normal or tangential to there), that are rotating together with the mesh around it.

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Now that we're done with Boundary Conditions, we're almost ready to run the simulation!

Save your project.

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