White water in fluid simulations can make or break realism. But how much do different parameters actually affect the final look? To find out, I ran 97 different simulations in Houdini, tweaking various white water settings to analyze their impact.
This study aims to answer two key questions:
✅ Which parameters have the most significant effect on white water behavior?
✅ Which settings barely make a difference?
The results might surprise you! While some parameters drastically changed the foam’s motion and appearance, others had minimal impact.
📌 Simulation Setup (Technical Breakdown)
💡 Key Elements of the Test:
- A 1-meter sphere drops into water in each test.
- White water parameters are adjusted one at a time.
- Simulations are 3x speed-up for quick comparison.
- Parameter values are displayed on-screen in each test.
🎯 Key Observations:
✔️ Some parameters completely transformed the look of the foam.
✔️ Others had almost no visible effect on the final result.
Image 1: Depth Range Comparison
🔍 Observation:
✔️ Lower Depth Range values create a stronger stretching effect in splashes.
✔️ Higher values result in less noticeable elongation.
✔️ Smaller values generally produce a more dynamic and visually interesting result.
💡 Personal Preference:
“I found that lower depth range values give a more dramatic and natural water splash effect, making the motion feel more dynamic.”
Image 2: Velocity Offset Comparison
🔍 Observation:
✔️ Higher Velocity Offset values create longer, more stretched foam trails.
✔️ However, at extreme values, the motion starts to look unnatural.
✔️ Lower values maintain a more physically accurate water behavior while still adding some stretching.
💡 Personal Preference:
“While higher values create a more dramatic effect, I found that lower Velocity Offset values result in a more natural and believable white water motion.“
Image 3: Base Advect Comparison
🔍 Observation:
✔️ Lower Base Advect values cause the foam to spread more independently, especially in the later frames where the water slows down.
✔️ Higher values keep the foam tightly following the water’s motion, resulting in a more natural connection between the fluid and white water.
💡 Personal Preference:
“I found that higher Base Advect values create a more cohesive and realistic foam movement, especially as the water loses velocity.”
Image 4: Base Velocity Comparison
🔍 Observation:
✔️ Higher Base Velocity values make the foam move faster and more aggressively, sometimes unnaturally.
✔️ Lower values slow down the foam motion, but too low can make it look disconnected from the water.
✔️ The default value (1.0) provides the most natural balance, keeping the foam in sync with the water movement.
💡 Personal Preference:
“From my tests, the default value (1.0) gives the best balance—maintaining a realistic motion without making the foam feel too exaggerated or sluggish.”
Parameters like Stiffness, Neighbor Size, Max Neighbors, PBF Inclusion, Constraint Iteration, Max Acceleration, and Tensile Q had little to no noticeable impact in this specific simulation. Therefore, I have omitted their comparison images.
From my tests, the default values for these parameters seem to work well, providing a balanced and stable simulation.
Image 5: Replants, Erosion & Upper Surface Comparison
🔍 Observations:
✔️ Enable Replants: This option is meant to help regenerate lost white water particles, but in my tests, it had no noticeable effect on the simulation.
✔️ Erosion: Controls how quickly white water dissipates over time. The effect was subtle and didn’t make a major difference in this case.
✔️ Upper Surface: This parameter significantly affects how foam is distributed on top of the water surface. It created a dramatic visual change, making it one of the most impactful settings.
💡 Personal Preference:
“Among these, Upper Surface had the biggest impact and was a great option to fine-tune the look of the foam.”
Final Thoughts & Conclusion
This test was a deep dive into how different White Water parameters in Houdini influence fluid behavior. Out of the 97 simulations, some parameters had a major impact on the look and motion of the foam, while others had little to no visible effect.
💡 Key Takeaways:
✅ Parameters like Depth Range, Velocity Offset, and Upper Surface made the most noticeable changes.
✅ Some settings, like Enable Replants & PBF Inclusion, had no visible effect in this scenario.
✅ The default values for many parameters worked well without the need for excessive tweaking.
These insights help fine-tune white water settings for more realistic and controlled simulations. I’ll continue experimenting with different conditions and setups to explore further refinements!