---
license: cc-by-nc-4.0
tags:
- CFD
- Multiphase
- CompressibleFlow
- SciML
- Droplets
- Shock
- 3D
pretty_name: 3D Shock-Induced Droplet Breakup in Air with Symmetric BC
size_categories:
- 1K<n<10K
---

# 3D Shock-Induced Droplet Breakup in Air with Symmetric BC
## Description

The dataset captures the time-evolving behavior of 3D spherical droplets subjected to an external shock wave in air.
When a shock wave impacts a droplet, the initial response—largely independent of the Weber number—is a deformation phase in which the droplet flattens.
This interaction with the shock wave results in two different breakup-modes of the droplet (SIE and RTP).
In the SIE regime, breakup is driven mainly by strong shear forces acting along the droplet surface. 
After the droplet has flattened, shear-induced disturbances emerge near the equator; these instabilities originate near the droplet equator after the droplet has flattened out in the first phase and are advected along the droplet surface. 
As the relative velocity between the droplet and the surrounding gas increases, these disturbances grow due to Kelvin–Helmholtz instability, eventually stripping liquid from the droplet and producing fine droplets downstream. 
In contrast, in the RTP regime, relatively stronger surface tension suppresses the growth of such shear instabilities, maintaining a smoother interface. 
As deformation progresses, the upstream side of the droplet becomes concave as the surrounding gas penetrates and pierces the liquid. 
Unlike RTP, the SIE regime is characterized by a continuous and gradual loss of mass, often resulting in a mist of droplets downstream.
Here we investigate a scenario with symmetric boundary conditions at the north, south, top and bottom walls.

<div style="display:flex;justify-content:center;gap:20px;flex-wrap: wrap;">
  <div>
    <video style="width:100%;max-width:800px" src="https://huggingface.co/datasets/FluidVerse/3D_SDBA_SSOOSS/resolve/main/SDBA_SSOOSS_RTP_Mas1.20.mp4" loop autoplay muted controls></video>
    <p style="position:relative;top:-30px;font-size:14px">Shock-Induced Droplet RTP-Breakup in Air (Mach 1.20)</p>
  </div>
  <div>
    <video style="width:100%;max-width:800px" src="https://huggingface.co/datasets/FluidVerse/3D_SDBA_SSOOSS/resolve/main/SDBA_SSOOSS_SIE_Mas1.20.mp4" loop autoplay muted controls></video>
    <p style="position:relative;top:-30px;font-size:14px">Shock-Induced Droplet SIE-Breakup in Air (Mach 1.20)</p>
  </div>
</div>

## About the data
|Metadata|Description|
|-----|------|
|Solver|[ALPACA](https://www.sciencedirect.com/science/article/abs/pii/S0010465521003581)|
|PDE|3D compressible Euler equations|
|Dimension|3D|
|Number of Trajectories|180|
|Train-Test-Split|0.8 - 0.2|
|Number of Timesteps|101|
|Simulation End Time|91 \\( \mu s \\) - 1240 \\( \mu s \\) (depending on the IC)|
|Save Interval|0.91 \\( \mu s \\) - 12.40 \\( \mu s \\) (depending on the IC)|
|Fields| - density_mixed <br/> - density_water <br/> - density_air <br/> - pressure <br/> - velocityX <br/> - velocityY <br/> - velocityZ <br/> - volume_fraction_water|
|Simulation Resolution|256x128x128 (Clipped and Downsampled)|
|Dataset Resolution|128x128x128|
|Grid Type|Cartesian Uniform Grid|
|Initial Condition|The droplets are in equilibrium with the surrounding pre-shock environment.|
|Boundary Conditions| North: Symmetry <br/> South: Symmetry <br/> Top: Symmetry <br/> Bottom: Symmetry <br/> East: Open <br/> West: Open|
|Conditioning Parameters| Shock Mach Number [1.2 - 3.2] <br/> Weber Number [10 - 30 & 10k - 30k] <br/> Droplet Count [1 - 5] <br/> Droplet Radius [2mm - 3.5mm] <br/> Droplet Center Position [Random in Domain]

Further metadata information and channel-wise statistics can be found in the corresponding `metadata.json` file.

## Dataset Structure 
The train.h5 and test.h5 in this repository are meta hdf5 files that link to multiple subparts inside the corresponding subset folder.
The mentioned train-test-split [0.8 - 0.2] is only valid when all subparts inside the subset folder are present.

## Key Challenges for Surrogate Modelling
- Distinguish breakup mode - RTP or SIE
- Accurate interface capturing
- Understanding wave dynamics
- Tracking droplet fragments
- Capture droplet interactions in the case of multi-droplets

## How to Download the Dataset

Download the whole dataset:
```
hf download FluidVerse/3D_SDBA_SSOOSS --repo-type dataset
```

Download only part of the dataset with resolution 128x128x128:
```
from huggingface_hub import snapshot_download

snapshot_download(
    repo_id="FluidVerse/3D_SDBA_SSOOSS",
    repo_type="dataset",
    allow_patterns="3d_shock_multi_droplet_breakup_in_air/128x128x128/Shock_Droplet_mixed_DPUVWD1D2Vf/*",
    local_dir="."
)
```