Compute interface stretching by means of a metric tensor [1,2,3,4], where the stretching value expresses change relative to one. A value larger than one indicates stretching, and a value smaller than one indicates contraction in the respective direction.
The following input ports are available:
| Input | Description | Type | Remark |
|---|---|---|---|
| Grid | Grid containing fields representing fluids in a multiphase setting. | Rectilinear Grid |
The grid contains the following data fields:
| Data field | Description | Data | Type | Remark |
|---|---|---|---|---|
| Volume of fluid field | A volume of fluid field, whose entries are in the range [0, 1]. | Scalar | Cell-based | |
| Interface gradients | Gradient at interface cells. | Vector | Cell-based | |
| Interface positions | Field containing the interface barycenter of each interface cell. | Vector | Cell-based | |
| Velocities | Velocity field describing the fluid flow. | Vector | Cell-based |
The following data fields are appended to the input grid:
| Data field | Description | Data | Type | Remark |
|---|---|---|---|---|
| Stretching (area) | Stretching expressed per area, where values >1 indicate stretching, and values <1 indicate contraction. | Scalar | Cell-based | |
| Stretching direction (minimum) | Direction corresponding to minimum stretching. | Vector | Cell-based | |
| Stretching direction (maximum) | Direction corresponding to maximum stretching. | Vector | Cell-based | |
| Stretching direction (largest) | Direction corresponding to strongest stretching or bending. | Vector | Cell-based |
The grid itself is not modified.
[1] Alexander Straub. Visualization of Interface Instabilities in Two-Phase Flow. University of Stuttgart, 2016.
[2] Alexander Straub, Grzegorz K. Karch, Sebastian Boblest, Jonas Kaufmann, Filip Sadlo, Bernhard Weigand, and Thomas Ertl. Visual Analysis of Interface Deformation in Multiphase Flow. Proceedings of the DIPSI Workshop 2018, Università degli studi di Bergamo, 45–47, 2018.
[3] Alexander Straub, Moritz Heinemann, and Thomas Ertl. Visualization and Visual Analysis for Multiphase Flow. Proceedings of the DIPSI Workshop 2019, Università degli studi di Bergamo, 25–27, 2019.
[4] Alexander Straub, and Thomas Ertl. Visualization Techniques for Droplet Interfaces and Multiphase Flow. Droplet Interactions and Spray Processes, Springer International Publishing, 121: 203–214, 2020.