1. Pavel Slavík, Marek Gayer, Frantisek Hrdlicka, Ondrej Kubelka Czech Technical University in Prague Czech Republic 2003 Winter Simulation Conference December 7-10 Fairmont Hotel New Orleans Louisiana, USA www.cgg.cvut.cz Problems of Visualization of Technological Processes

2. www.cgg.cvut.cz 2WSC 2003 Outline of the presentation Need for visualization of dynamic phenomena Example of a system for filter design Dynamic phenomena and their visualization Brief introduction to Fluid Simulators and Solvers Our solution overview –Fluid simulator and coal particle system –Fluid Simulator State Extension (FSS) Control of visualization dynamics Conclusion and future work

3. www.cgg.cvut.cz 3WSC 2003 The need for visualization of dynamic processes Dynamic processes and understanding to their nature (e.g. in engineering education) Classical approach: animation Disadvantage of this approach: no interaction during the course of the process Solution: on-line interaction with visualization module

4. www.cgg.cvut.cz 4WSC 2003 Our approach Development of new simulation methods that are fast enough to generate sufficient number of frames for the controlled animation Development of new visualization methods that allow extensive control of dynamic parameters of the process visualized

5. www.cgg.cvut.cz 5WSC 2003 Two applications Design of flue gas filter Combustion processes Both cases: problems of flow dynamics Traditional solutions: time consuming Our solution is based on fluid simulator and particle systems Simulations run much faster (in orders)

6. www.cgg.cvut.cz 6WSC 2003 Active coal filter: Integral - function scheme new active coal saturated active coal clean gas dirty flue gas

7. www.cgg.cvut.cz 7WSC 2003 Traditional designs of filters : Ad hoc design Real model Testing the real model Modification of the real model Testing the real model Modification …… Very costly and the filter efficiency is often questionable

8. www.cgg.cvut.cz 8WSC 2003 Simulation and visualization of filter behavior Two aspects have been taken into account: Physical behavior – behavior of granule flow Adsorption behavior – adsorption capability of granules and its effect on gas cleaning

9. www.cgg.cvut.cz 9WSC 2003 Verification of the model Real test Simulation of granule flow

10. www.cgg.cvut.cz 10WSC 2003 Simulation of more complex configurations Angle of inner louvers 10°20°30°

11. www.cgg.cvut.cz 11WSC 2003 Our approach to dynamic visualization To get maximum information from the picture we can zoom its interesting parts Visualization mantra: Overview, zoom, details-on-demand The same approach should be used for dynamic visualization – “zoom in time” Time segments with interesting dynamic behavior are identified and the visualization is slowed down

12. www.cgg.cvut.cz 12WSC 2003 Visualization of granules flow !@!!

13. www.cgg.cvut.cz 13WSC 2003 Future work Model of the dynamic behavior of granules (verified) Model of adsorption it corresponds with data acquired from filter producers Creation of proper user interface that should allow the users to dynamically influence the speed of flow of granules

14. www.cgg.cvut.cz 14WSC 2003 Physical device for real tests

15. www.cgg.cvut.cz 15WSC 2003 Introduction and motivation to coal combustion modeling and visualization Both for the ecological and economical reasons Finding optimal boiler configurations –To reduce pollution –Combustion optimization –To find a way for optimal fuel preparation How can visualization help

16. www.cgg.cvut.cz 16WSC 2003 Traditional Fluid Simulators and Solvers For simulation and visualization of various nature phenomena: –Water and liquids –Clouds, smoke –Fire and combustion –Special effects

17. www.cgg.cvut.cz 17WSC 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

18. www.cgg.cvut.cz 18WSC 2003 Our system overview Allows dynamic, interactive overview of the combustion process Real-time simulation and visualization (currently using 2D model simplification) Designed on following key parts –Fluid simulator –Virtual coal particle system –Simplified combustion engine

19. www.cgg.cvut.cz 19WSC 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

20. www.cgg.cvut.cz 20WSC 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

21. www.cgg.cvut.cz 21WSC 2003 t = 0 seconds: T = 343 o C (above ignition) O 2 concentration = 25% Coal particle Partially burned particle C C C t = 0.01 seconds: T = 345 o C (increased) O2 concentration = 24% Partially burned coal particles Coal particle transformed to burned ash particle C B C C C Interaction of virtual coal particles

22. www.cgg.cvut.cz 22WSC 2003 Results comparison – global parameters ParameterOur systemFLUENT 5.5 Average Temperature890 o C1002 o C Outlet Temperature814 o C1068 o C Max Temperature2546 o C2488 o C Average stream velocity14 m/s11 m/s Average outlet velocity56 m/s48 m/s Wattage187 W/m 3 232 W/m 3 Mass total21.1 kg21.3 kg Solution converge timeBelow 1 minIn hours Real-time simulation / visualization Enabled, 10 FPS+ Not available

23. www.cgg.cvut.cz 23WSC 2003 Sample visualization - cell characteristics

24. www.cgg.cvut.cz 24WSC 2003 Sample visualization – coal particles

25. www.cgg.cvut.cz 25WSC 2003 Sample visualization of particle characteristics (particle tracks)

26. www.cgg.cvut.cz 26WSC 2003 Our interactive combustion system

27. www.cgg.cvut.cz 27WSC 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 Our concept: Pre-calculated Fluid Simulator States (FSS)

28. www.cgg.cvut.cz 28WSC 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

29. www.cgg.cvut.cz 29WSC 2003 Simulation system architecture

30. www.cgg.cvut.cz 30WSC 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 resulting in better interactivity No seeking and skip frame ability + + + - +

31. www.cgg.cvut.cz 31WSC 2003

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33. www.cgg.cvut.cz 33WSC 2003 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

34. www.cgg.cvut.cz 34WSC 2003 Forming FSS to tree cluster structure

35. www.cgg.cvut.cz 35WSC 2003 Changing simulation parameters in each of the tree node

36. www.cgg.cvut.cz 36WSC 2003 Thank you for your attention. ?????? Do you have any questions ?