Bubble Simulation for the Hysteroscopy Simulator

Michel EstermannEveline MattleFebruar 2006

VR in Medicine Homework

Contents

• Hysteroscopy Simulator

• Bubbles

• Forces acting on a bubble

• Velocity of a bubble

• Results

• Discussion and Conclusions

VR in Medicine Homework

Hysteroscopy Simulator

VR in Medicine Homework

Hysteroscopy Simulator

VR in Medicine Homework

Bubble

• Model: – Sphere with radius r

• Generation:– Bubblepool– Randomly generated size– During cutting

• Display: – Billboarding

VR in Medicine Homework

Forces acting on a Bubble

• Buoyancy

• Gravity

• Forces between two bubbles– Repelling force– Viscous force

• Forces between bubbles and objects– Repelling force– Viscous force

• Influence of the Fluid velocity on a bubble

VR in Medicine Homework

Velocity of a bubble

• Because it is assumed, that the bubbles have no mass the sum of all the forces has to be zero.

• Some of the forces are dependent of the velocity of the bubbles, so a equation for the velocity can be found.

• With the velocity the position of the bubbles can be calculated discretely.

VR in Medicine Homework

Results

VR in Medicine Homework

Results

• Several assumptions and approximations used in this work leads to certain limitations:

– Large velocity changes between update-steps possible– Considering time for independence of computation time– No deformation of bubbles– No fusion of bubbles– Difficulties to find the right parameters– Current implementation: no interaction with the objects

VR in Medicine Homework

Discussion and Conclusions

• Because the bubbles interact now with themselves and with the fluid around them the simulation looks more realistic.

• Because of the Buoyancy an important information about the orientation is given.

• Next step: implement the interaction of the bubbles with the objects.

VR in Medicine Homework

References

• [1] (2005) –hysteroscopy simulator website. Available: http://www.hystsim.ethz.ch

• [2] S.T. Greenwood and D. H. House, “Better with bubbles: Enhancing the visual realism of simulated fluid”, in SCA ’04: Proc. Of the 2004 ACM SIGGRAPH/Eurographics symposium on Computer animation. New York, NY, USA: ACM Press, 2004, pp. 287-296 [online]. Available: http://portal.acm.org/citation.cfm?id=10028562

• [3] H. Kueck, C. Vogelsang, and G. Greiner, “Simulation and rendering of liquid foams”, Proc. Graphics Interface ’02, pp.81-88, 2002. [Online]. Available: http://www.graphicsinterface.org/proceedings/2002/145/

• [4] D. J. Durian, “Foam mechanics at the bubble scale”, Physical Review Letters, vol 75, no. 26, pp. 4780-4783, 1995. [Online]. Available: http://prola.aps.org/abstract/PRL/v75/i26/p4780_1

Thanks for your attention!