Pre-calculated Fluid Simulator States Tree

Marek Gayer and Pavel Slavík

Computer Graphics GroupDepartment of Computer Science and EngineeringFaculty 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

www.cgg.cvut.cz

2ASM 2003

www.cgg.cvut.cz

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

www.cgg.cvut.czFluid 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

www.cgg.cvut.cz

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

www.cgg.cvut.czStoring 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

www.cgg.cvut.cz

Our Fluid Simulator Dividing boiler area

to structured grid cell arrays containing:– Velocities– Masses/Pressures– O2 concentrations– Temperatures

State update Principle of local

simulation

7ASM 2003

www.cgg.cvut.cz

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

www.cgg.cvut.czExtending 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

www.cgg.cvut.czSimulation system architecture

VisualizationVisualization

InteractionInteractionStore FullData Sets

Store FullData Sets

Fluid simulatorFluid simulator

Combustion &heat transfer

engine

Combustion &heat transfer

engineParticlesystem

ParticlesystemGrid cellsGrid cells

Store FSSextension

Store FSSextension

10ASM 2003

www.cgg.cvut.czFeature comparison against data sets

Much less disk requirements (only fluid simulator states are being saved)

Lower disk bandwidthBetter scalability for large grids and/or

tasks with many particlesSame or even better accelerationNo seeking and skip frame ability

Note: Please refer to our paper for more detailed comparison and samples with performance measurements and discussions

+

++

-+

11ASM 2003

www.cgg.cvut.czForming FSS to tree cluster structure

12ASM 2003

www.cgg.cvut.czChanging simulation parameters in each of the tree node

13ASM 2003

www.cgg.cvut.cz

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

www.cgg.cvut.czOur interactive combustion system

15ASM 2003

www.cgg.cvut.cz

16ASM 2003

www.cgg.cvut.cz

17ASM 2003

www.cgg.cvut.czConclusion 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

www.cgg.cvut.czThank you for your attention.

???Do you have any questions ?