💥💥💥 How to create new coordinate system in Ansys Fluent?

 It seems that you want to create a new coordinate system in Ansys Fluent for your simulation. There are different ways to do that, depending on your needs and preferences. Here are some possible options:

• You can use the Coordinate Systems branch in Ansys Mechanical to insert a new coordinate system and define its origin, orientation, and type. You can then export the mesh to Ansys Fluent and use the Transform option in the Mesh menu to apply the new coordinate system to the mesh. You can find more details and screenshots about this method in this article¹.
• You can use the Define menu in Ansys Fluent to create a new coordinate system and specify its properties. You can then use the Set option in the Grid menu to select the new coordinate system as the active one for the simulation. You can find more information and examples about this method in this forum thread².
• You can use a User Defined Function (UDF) in Ansys Fluent to create a new coordinate system and perform coordinate transformations for your variables. This method requires some programming skills and knowledge of the UDF syntax and structure. You can find some tips and code snippets about this method in this forum thread³.

What is the difference between a global and local coordinate system?

A global coordinate system is a fixed reference frame that describes the position and orientation of objects in a simulation or a real-world scenario. A local coordinate system is a movable reference frame that is attached to a specific object and can change its position and orientation relative to the global coordinate system. The local coordinate system is often defined according to the shape and symmetry of the object. For example, an airplane may have a local coordinate system with the x-axis aligned along the fuselage axis of the body and the y-axis pointing along the port wing¹.

The difference between a global and local coordinate system is important for defining and transforming the coordinates of objects and signals in a simulation or a real-world scenario. For example, when a signal interacts with a sensor or a target, the interaction is usually specified as a function of the sensor or target local coordinates. However, when a signal propagates in the global coordinate system, the ray paths that connect transmitters, targets, and receivers are specified in global coordinates. Therefore, one needs to be able to convert local coordinates to global coordinates, and vice versa, using appropriate transformation matrices or functions²³.

How to apply new coordinates to my simulation in Ansys Fluent ?

To apply new coordinates to your simulation in Ansys Fluent, you need to follow these steps:

• First, you need to create a new coordinate system and specify its properties using the Define menu in Ansys Fluent. You can find more information and examples about this method in this forum thread¹.
• Next, you need to use the Set option in the Grid menu to select the new coordinate system as the active one for the simulation. This will affect the display of the mesh and the results in the graphics window, as well as the input and output of the boundary conditions and the reports.
• Finally, you need to use the Transform option in the Mesh menu to apply the new coordinate system to the mesh. This will change the coordinates of the mesh nodes and the cell volumes according to the new coordinate system. You can also use this option to scale, translate, or rotate the mesh.

Alternatively, you can use a User Defined Function (UDF) in Ansys Fluent to create a new coordinate system and perform coordinate transformations for your variables. This method requires some programming skills and knowledge of the UDF syntax and structure. You can find some tips and code snippets about this method in this forum thread².

What is the difference between scaling and rotating the mesh?

Scaling and rotating the mesh are two different ways of transforming the mesh geometry in Ansys Fluent. Scaling the mesh means changing the size of the mesh elements by a certain factor, while rotating the mesh means changing the orientation of the mesh elements by a certain angle. Both scaling and rotating the mesh can affect the accuracy and stability of the simulation, as well as the physical interpretation of the results.

Scaling the mesh can be useful for adjusting the dimensions of the mesh to match the desired units or the physical size of the problem. For example, if the mesh was created in meters, but the problem requires centimeters, scaling the mesh by a factor of 0.01 can convert the mesh units to centimeters. However, scaling the mesh can also introduce errors or distortions in the mesh quality, especially if the scaling factor is not uniform in all directions. For example, if the mesh is scaled by a factor of 2 in the x-direction, but by a factor of 0.5 in the y-direction, the mesh elements will become elongated and skewed, which can affect the numerical solution and the boundary layer resolution. Therefore, scaling the mesh should be done with caution and only when necessary.

Rotating the mesh can be useful for aligning the mesh with the desired coordinate system or the physical orientation of the problem. For example, if the mesh was created with the x-axis pointing north, but the problem requires the x-axis pointing east, rotating the mesh by 90 degrees around the z-axis can change the mesh orientation to match the problem. However, rotating the mesh can also introduce errors or inconsistencies in the mesh coordinates, especially if the rotation angle is not a multiple of 90 degrees. For example, if the mesh is rotated by 45 degrees around the z-axis, the mesh coordinates will no longer be aligned with the Cartesian axes, which can affect the input and output of the boundary conditions and the reports. Therefore, rotating the mesh should be done with care and only when necessary.

To learn more about scaling and rotating the mesh in Ansys Fluent, you can refer to the following sources:

• Applying Translations, Scaling, Reflection, and Rotation via the Deformed Geometry and Moving Mesh Interfaces¹
• Use 3D Transform Gizmo in After Effects²
• Why is it important to apply transformation to an objects data?³