Pre-calculated Fluid Simulator States Tree Marek Gayer and Pavel Slavík C omputer G raphics G roup Department of Computer Science and Engineering Faculty of Electrical Engineering of CTU in Prague Czech Republic The IASTED International Conference on APPLIED SIMULATION AND MODELLING ~ASM 2003~ September 3 - 5, 2003 Marbella, Spain

2ASM 2003 Outline of the presentation Brief introduction to Fluid Simulators and Solvers Using storage for real-time data replaying Our solution overview –Fluid simulator –Virtual coal particle system –Fluid Simulator State Extension (FSS) –Fluid Simulator State Tree (FSS Tree) Demonstration of results Conclusion and future work

3ASM 2003 Fluid Simulators and Solvers For simulation and visualization of various nature phenomena: –Water and liquids –Clouds, smoke –Fire and combustion –Special effects ACM SIGGRAPH Proceedings (see references in our paper)

4ASM 2003 Real-time modeling of fluids Most often: solving differential equations (e.g. Navier-Stokes) Real-time fluid simulator and solvers limitations and conditions: –Low resolution and/or 2D grid –Simplified physical models and computations –Code optimization

5ASM 2003 Storing results for real-time replaying Results are stored on hard disk, then real-time replayed –Data sets for selected characteristics –AVI and MPEG files –Limited interaction Our concept: Pre-calculated Fluid Simulator States Tree

6ASM 2003 Our Fluid Simulator Dividing boiler area to structured grid cell arrays containing: –Velocities –Masses/Pressures –O 2 concentrations –Temperatures State update Principle of local simulation

7ASM 2003 Virtual coal particle system Used for both simulation and visualization of the combustion process Virtual particle system approach Simplified combustion and heat transfer computation

8ASM 2003 Extending Fluid Simulator with FSS Simulation is divided into two phases: –Storing phase - fluid simulator states for each time step are saved on HDD –Replaying phase - simulation runs accelerated with pre-calculated fluid simulator states Except first frame, no other data are saved (e.g. particles) State files are stored in binary files

9ASM 2003 Simulation system architecture

10ASM 2003 Feature comparison against data sets Much less disk requirements (only fluid simulator states are being saved) Lower disk bandwidth Better scalability for large grids and/or tasks with many particles Same or even better acceleration No seeking and skip frame ability Note: Please refer to our paper for more detailed comparison and samples with performance measurements and discussions

11ASM 2003 Forming FSS to tree cluster structure

12ASM 2003 Changing simulation parameters in each of the tree node

13ASM 2003 FSS tree advantages Incremental and step by step solution Re-playable results of the simulation Interactive addition and deleting of parts Hierarchical storage of various states Interactive change of boundary conditions in each of the nodes Constructing various paths in the tree Extending of already computed tasks

14ASM 2003 Our interactive combustion system

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17ASM 2003 Conclusion and future research Concept of Pre-calculated Fluid Simulator States Tree offers: –Acceleration of Fluid Simulator based applications –Much less disk space & bandwidth requirements compared to using corresponding data sets –Better scalability compared to data sets –Incremental, hierarchical solution of fluid based tasks with interesting features Future research: –Compression of state data –Testing with very large data sets –Various data Interpolation techniques

18ASM 2003 Thank you for your attention. ?????? Do you have any questions ?