Compute interface deformation by means of the derived quantities interface stretching [1,2,3,4] and interface bending [2,3,4].
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 | |
| Velocities | Velocity field describing the fluid flow. | Vector | Cell-based | Optional |
The following parameters can be set by the user:
| Parameter | Description | Type | Accepted values | Default value |
|---|---|---|---|---|
| Surface tension | Calculate and use surface tension force instead of input velocity field. Must be set to True when omitting the velocity field input. Note that this is an experimental feature and is probably far from physically correct. |
Boolean | False | |
| Coefficient | Surface tension coefficient based on the involved species. | Float | >0 | 72.75 |
| Density | Density of the liquid phase. | Float | >0 | 0.9982 |
| Time step | Alternative time step for scaling the surface tension force vectors. If set to zero, use time step derived from the dataset. | Float | ≥0 | 0.0 |
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 | |
| Bending (minimum) | Minimum bending, where bending values >0 indicate increase in concavity, and values <0 indicate increase in convexity. | Scalar | Cell-based | |
| Bending (maximum) | Maximum bending, where bending values >0 indicate increase in concavity, and values <0 indicate increase in convexity. | Scalar | Cell-based | |
| Bending (absolute maximum) | Strongest bending, where bending values >0 indicate increase in concavity, and values <0 indicate increase in convexity. | Scalar | Cell-based | |
| Bending direction (minimum) | Direction corresponding to minimum bending. | Vector | Cell-based | |
| Bending direction (maximum) | Direction corresponding to maximum bending. | Vector | Cell-based | |
| Bending direction (absolute maximum) | Direction corresponding to strongest bending. | Vector | Cell-based | |
| Interface gradient | Within interface cells, it contains the computed gradient, elsewhere it is set to a zero-vector. | Vector | Cell-based | Only available when compiled with detailed output. |
| Interface position | Field containing the interface barycenter of each interface cell. | Vector | Cell-based | Only available when compiled with detailed output. |
| Interface curvature | The curvature at the interface barycenter. | Scalar | Cell-based | Only available when compiled with detailed output, and surface tension force computation turned on. |
| Surface tension force | Approximate surface tension force in interface cells. | Vector | Cell-based | Only available when compiled with detailed output, and surface tension force computation turned on. |
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.