Updating older models to use new Crosswind Diffusion formulation

Solution Number: 1165
Title: Updating older models to use new Crosswind Diffusion formulation
Platform: All Platforms
Applies to: CFD Module, Chemical Reaction Engineering Module
Versions: 4.3b, 4.4, 5.0, 5.1
Categories: Physics
Keywords: CFD stabilization

Problem Description

In COMSOL 4.3b (released May 2013) the Crosswind diffusion formulation was updated for all flow interfaces supporting Crosswind diffusion. This means that models solved with the new formulation, i.e in COMSOL 4.3b and subsequent versions, can give slightly different results compared to models solved in prior versions.

Any model file created in previous versions will retain the old crosswind formulation if the crosswind diffusion was active. You can change to the new crosswind diffusion in older models as described below.

Solution

  1. The new formulation becomes available in 4.3b if the old physics interface is replaced with a new physics interface.
  2. Alternatively, open COMSOL 4.3a and deactivate crosswind diffusion. Save the model file. Then open the model in the never version of COMSOL and reactivate the crosswind diffusion stabilization to get the new formulation.

In addition the two physics "Transport of Diluted Species" and "Nernst-Planck convection and diffusion" have the option to toggle between the old and new Crosswind Diffusion formulation.

For more information, either search the Help (press F1 in COMSOL Multiphysics) for terms such as crosswind diffusion, or open the electronic Documentation (press Ctrl F1 in COMSOL Multiphysics) and then browse the available PDFs.


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