Custom Heat Transfer Coefficients in Altair Flow Simulator

JimBruns
JimBruns
Altair Employee
edited 7:41PM in Altair HyperWorks

Flow Simulator (FS) has many built-in heat transfer coefficient (HTC) correlations, but FS may not include a correlation required by the user. Fortunately, it is easy to add your own correlation to FS. This blog explores the customization manager for HTC correlations.

There are numerous HTC correlations in the public domain and about 3 dozen have been added to FS. However, there will always be different HTC correlation requirements for unique geometries or flow conditions. Furthermore, companies may require proprietary correlations based on company experience. FS includes the capability to add a custom HTC correlation to your model.

Customization Manager

The Customization Manager is the best option for adding a custom HTC. Once a correlation is set up, it is easy to apply to different elements in different models by different users. In other words, it is easy to apply and share. Follow these steps to create a simple duct HTC correlation and remember the help is a click away, “?”.

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  1. Open the Customization Manager from the PreProcessing list and click “New”
  2. Give the correlation a unique name. This is the name that will show up in the property editor.
  3. Choose Python. Fortran is the other option. Fortran is the faster solver option and is recommended for correlations that will be used a lot. Python is simpler to set up and is a good option for development and learning the customization manager.
  4. Choose the Subtype. The Subtype determines which flow elements (or thermal resistors) can use the custom correlation. TURBULENT_DUCT_NU can be used by the tube flow elements.
  5. Some information is automatically sent to the python function, but if the correlation requires further inputs enter their names here. (OPTIONAL)
  6. The units of the information passed to the custom correlation and the units of the HTC passed back to the solver are controlled here. English = FlowSimulator unit set and SI=SI unit set.
  7. Enter the python script. Recommend starting very simple. Even returning a constant HTC is a good place to begin. The GUI automatically populates the variables sent to and returned from the python script. See the variable comments for further information.
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Now that the correlation is done, it can be applied to the standard, advanced, or incompressible tube elements. The custom correlation name appears at the bottom of the HTC Relation list. (A custom correlation with subtype of Laminar_Duct_Nu would appear in the Laminar HTC Relation list.)

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Check the *.res file for the HTC results.

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Use the Customization Manager’s “Export” button to export a file containing the custom correlations (*.cm). This file can be read into another model using the Customization Manager’s “Import” button.

The FS help documentation for the customization manager includes all the different subtypes available (ex: friction, labseal losses, Cdcomp adjustments). See the FS help documents for information on the Fortran language option and functions to get additional information to use in the correlation.

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