### 6.6.1. Fourier Transformation: Workflow Requirements

The basic procedure for setting up a Transient Blade Row model is outlined in Setting up a Transient Blade Row Model. When your simulation involves the Fourier Transformation model, your workflow should include the following steps:

- Each turbo component requires two instances of the passages that constitute a repeatable section. A GGI interface must be created to join the two instances. This domain interface will be selected as the sampling interface. A periodic domain interface connection is required on the outer periodic boundaries. This periodic interface is selected when defining the phase corrected interface. See Fourier Transformation Disturbance Settings in the CFX-Pre User's Guide for a description of the sampling domain interface.

- For a given domain, optionally add one disturbance to the list of disturbances.

- Those transient rotor stator interfaces not referenced by a disturbance will be treated with the Profile Transformation method.

- All periodic and sampling interface pairs must use the `Bitmap` intersection method. The option that controls the intersection method is found in CFX-Pre in the details view for the domain interface, on the Basic Settings tab, under Mesh Connection Method > Mesh Connection > Intersection Control. For periodic and sampling interface pairs, the `Bitmap` method takes effect when the Intersection Control check box is cleared. When the Intersection Control check box is selected, the Option setting is set to `Bitmap` by default.

- The Transient Rotor Stator interface must use the `Direct` intersection method. The option that controls the intersection method is found in CFX-Pre in the details view for the domain interface, on the Basic Settings tab, under Mesh Connection Method > Mesh Connection > Intersection Control. For a Transient Rotor Stator interface, the `Direct` method takes effect when the Intersection Control check box is cleared. If you select the Intersection Control check box, you must change the Option setting (from its default value of `Bitmap`) to `Direct`.

- Ensure that no disturbance signal has a speed of zero relative to the component on which that signal acts.

- When solving a simulation that involves the Fourier Transformation method (including the steady-state simulation for initialization), the use of double precision is strongly recommended for accuracy and robustness.

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