Volume fraction cutoff

M_H215 · August 26, 2015, 17:47

Hi
I have a question about volume fraction cutoff.

What is it exactly? Is it related to accuracy of the solution?
Thank you

landerfwc · September 29, 2015, 10:06

See The Fluent Manual:

The Volume Fraction Cutoff allows you to specify a cutoff limit for the volume fraction values. The value that you provide is used as the lower cutoff for the volume fraction. All volume fraction values in the domain below this cutoff value are set to zero. The upper cutoff is calculated as (1.0 - lower cutoff). All volume fraction values above the upper cutoff value are set to 1.0. The default value is 1e-6, which is the recommended value. Using a higher value may lead to a higher volume imbalance.

Important: The Volume Fraction Cutoff value can be specified when using the VOF model, or when using the Eulerian Multiphase model with the Explicit formulation.

Note: For the Implicit formulation, the minimum value allowed is 0 and the maximum allowable value is 1e-6. For the Explicit formulation, the minimum value allowed is 0 and the maximum allowable value is 1e-4. A higher cutoff value is available with the Explicit formulation because it allows for the local redistribution procedure of partially filled cells, which accounts for volume loss. This treatment is not available with the Implicit formulation.

August 26, 2015, 17:47	Volume fraction cutoff	#1
M_H215 New Member Mohammad Join Date: Apr 2015 Posts: 17 Rep Power: 11	Hi I have a question about volume fraction cutoff. What is it exactly? Is it related to accuracy of the solution? Thank you

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September 29, 2015, 10:06		#2
landerfwc New Member Join Date: Jun 2014 Posts: 17 Rep Power: 12	See The Fluent Manual: The Volume Fraction Cutoff allows you to specify a cutoff limit for the volume fraction values. The value that you provide is used as the lower cutoff for the volume fraction. All volume fraction values in the domain below this cutoff value are set to zero. The upper cutoff is calculated as (1.0 - lower cutoff). All volume fraction values above the upper cutoff value are set to 1.0. The default value is 1e-6, which is the recommended value. Using a higher value may lead to a higher volume imbalance. Important: The Volume Fraction Cutoff value can be specified when using the VOF model, or when using the Eulerian Multiphase model with the Explicit formulation. Note: For the Implicit formulation, the minimum value allowed is 0 and the maximum allowable value is 1e-6. For the Explicit formulation, the minimum value allowed is 0 and the maximum allowable value is 1e-4. A higher cutoff value is available with the Explicit formulation because it allows for the local redistribution procedure of partially filled cells, which accounts for volume loss. This treatment is not available with the Implicit formulation.