Two new research papers have landed on a homepage of Dr. Matthias Müller-Fischer, PhysX SDK Research Lead in NVIDIA and NovodeX co-founder.

Fisrst one, called “Real-Time Eulerian Water Simulation Using a Restricted Tall Cell Grid“, presents further impovements to the real-time hybrid fluid solver, that we were able to see in recent demos like Lighhouse and Raging Rapids Ride.

Abstract:

We present a new Eulerian fluid simulation method, which allows real-time simulations of large scale three dimensional liquids. Such scenarios have hither to been restricted to the domain of off-line computation. To reduce computation time we use a hybrid grid representation composed of regular cubic cells on top of a layer of tall cells. With this layout water above an arbitrary terrain can be represented without consuming an excessive amount of memory and compute power, while focusing effort on the area near the surface where it most matters. Additionally, we optimized the grid representation for a GPU implementation of the fluid solver.

To further accelerate the simulation, we introduce a specialized multigrid algorithm for solving the Poisson equation and propose solver modifications to keep the simulation stable for large time steps. We demonstrate the efficiency of our approach in several real-world scenarios, all running above 30 frames per second on a modern GPU. Some scenes include additional features such as two-way rigid body coupling as well as particle representations of sub-grid detail.

We badly want to see this one in further releases of PhysX SDK 3 or APEX.

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In a recent promo video for upcoming GTX 560 GPU, NVIDIA has spoiled next game with support of GPU accelerated PhysX effects – Alice: Madness Returns, sequel to American McGee’s visionary classic “Alice” title.

UPDATE: Comparison GPU PhysX video

Starting at 1:34, comparison PhysX sequences are showcased. According to the video, GPU PhysX content in Alice will include (following list may be not full) destructible environments..

..volumetric fluid effects (for example, oil-like fluid from damaged enemies)..

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Interesting paper, called “Scalable Fluid Simulation using Anisotropic Turbulence Particles” has appeared at homepage of Dr. Markuss Gross, from ETH Zurich.

As far as we know, same solver is used in APEX Turbulence module.

Abstract:

It is usually difficult to resolve the fine details of turbulent flows, especially when targeting real-time applications. We present a novel, scalable turbulence method that uses a realistic energy model and an efficient particle representation that allows for the accurate and robust simulation of small-scale detail. We compute transport of turbulent energy using a complete two-equation k–e model with accurate production terms that allows us to capture anisotropic turbulence effects, which integrate smoothly into the base flow. We only require a very low grid resolution to resolve the underlying base flow.

As we offload complexity from the fluid solver to the particle system, we can control the detail of the simulation easily by adjusting the number of particles, without changing the large scale behavior. In addition, no computations are wasted on areas that are not visible. We demonstrate that due to the design of our algorithm it is highly suitable for massively parallel architectures, and is able to generate detailed turbulent

In addition, this paper comes with nice video demonstration (92 mb). It is worth to watch.

Thanks to AquaGeneral for the link.

Another paper called “Real-Time Simulation of Large Bodies of Water with Small Scale Details” (you can find previous one, Wrinkle Meshes, here) has arrived from Dr. Matthias Müller-Fischer, PhysX SDK research lead at Nvidia Switzerland.

Paper is decribing hybrid grid- and – particle based fluid solver used in latest, and technically most impressive, demo from Nvidia – Raging Rapids Ride.

Abstract:

We present a hybrid water simulation method that combines grid based and particles based approaches. Our specialized shallow water solver can handle arbitrary underlying terrain slopes, arbitrary water depth and supports wet-dry regions tracking. To treat open water scenes we introduce a method for handling non-reflecting boundary conditions. Regions of liquid that cannot be represented by the height field including breaking waves, water falls and splashing due to rigid and soft bodies interaction are automatically turned into spray, splash and foam particles.

The particles are treated as simple non-interacting point masses and they exchange mass and momentum with the height field fluid. We also present a method for procedurally adding small scale waves that are advected with the water flow. We demonstrate the effectiveness of our method in various test scene including a large flowing river along a valley with beaches, big rocks, steep cliffs and waterfalls.

We still hope that this solver will make it into next, 3.x release of PhysX SDK.

In addition, demonstrational video is available (61 mb)