1. Real-time Simulation and Visualization using Pre-calculated Fluid Simulator States Marek Gayer, Pavel Slavík and František Hrdlička Computer Graphics Group Department of Computer Science and Engineering Faculty of Electrical Engineering of CTU in Prague Czech Republic 7 th International Conference, Information Visualization, London, July 16-18 2003 www.cgg.cvut.cz

2. 2IV03 London Outline of the presentation Brief introduction to Fluid Simulators and Solvers Our solution overview –Fluid simulator –Virtual coal particle system –Fluid Simulator State Extension (FSS) Comparison against data sets Demonstration of results Conclusion and future work

3. www.cgg.cvut.cz 3IV03 London 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)

4. www.cgg.cvut.cz 4IV03 London 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

5. www.cgg.cvut.cz 5IV03 London 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 Our concept: Pre-calculated Fluid Simulator States (FSS)

6. www.cgg.cvut.cz 6IV03 London Our system overview Allows dynamic overview of the combustion process Real-time simulation and visualization (currently using 2D model simplification) Designed on following key parts –Fluid simulator with FSS extension –Virtual coal particle system –Simplified combustion engine

7. www.cgg.cvut.cz 7IV03 London 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

8. www.cgg.cvut.cz 8IV03 London Virtual coal particle system Used for both simulation and visualization of the combustion process Virtual particle system approach Simplified combustion and heat transfer computation

9. www.cgg.cvut.cz 9IV03 London 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

10. www.cgg.cvut.cz 10IV03 London Simulation system architecture

11. www.cgg.cvut.cz 11IV03 London 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 + + + - +

12. www.cgg.cvut.cz 12IV03 London Detailed comparison against data sets Store method / Grid size FSS / 20*40 FULL / 20*40 FSS / 50*100 FULL / 50*100 Simulation time1214s1230s5128s5133s Write [MB/s]0.168.00.33.7 Replay time627s603s816s864s Read [MB/s]0.3114.61.921.95 AVG Fps19.119.916.315.4 Disk space GB0.29.41.619.1 Total accelerationx 1.9x 2.0x 6.2x 5.9

13. www.cgg.cvut.cz 13IV03 London Our interactive combustion system

14. www.cgg.cvut.cz 14IV03 London

15. www.cgg.cvut.cz 15IV03 London Conclusion and future research Concept of Pre-calculated Fluid Simulator States offers: –Acceleration of Fluid Simulator based applications –Much less disk space & bandwidth requirements compared to using corresponding data sets –Better scalability then data sets Future research: –Compression state data using GZIP –Testing with very large data sets –Pre-calculated Fluid Simulator States Tree

16. www.cgg.cvut.cz 16IV03 London Thank you for your attention. ?????? Do you have any questions ?