Exploring Viscosity Models for Simulating Non-Newtonian Behavior in Cerebral Blood Flow
Khayat, Asraf (2023)
2023
Sähkötekniikan DI-ohjelma - Master's Programme in Electrical Engineering
Informaatioteknologian ja viestinnän tiedekunta - Faculty of Information Technology and Communication Sciences
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Hyväksymispäivämäärä
2023-10-13
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tuni-202309278486
https://urn.fi/URN:NBN:fi:tuni-202309278486
Tiivistelmä
In this thesis, five different viscosity models were tested in a simulation time of 8 and 17 seconds. The simulation domain, in which the simulations were run, was real 7-Tesla magnetic resonance imaging data. The used data was meshed into tetrahedra for finite element method simulations, and the Navier-Stokes equations were employed to solve for velocity and pressure values. Zeffiro interface tool was used and the finite element method computations were already implemented. Only the viscosity models were added to the existing tool. The viscosity models examined include the constant, Carreau-Yasuda, Walburn-Schenck, Generalized power law, and Casson models.
The primary objective was to assess whether the choice of viscosity model influences simulation outcomes and whether any model exhibits superior performance.
Simulation results are presented through figures, displaying velocity, pressure, and viscosity values in specific regions of the domain for both shorter and longer simulation times. Additionally, forward and backward wave separation analysis was conducted during the longer simulations.
The results show that using a varying viscosity model had a damping effect on the velocity values, and the wave separation seemed to work slightly better when the varied viscosity model was used. However, no significant variations were observed in pressure values across the different viscosity models. While a definitive determination of the best-performing model could not be made, it is recommended to use a varying viscosity model to dampen the velocity values within the system. Notably, the Casson model demonstrated behaviour similar to that of constant viscosity and is therefore not recommended.
The primary objective was to assess whether the choice of viscosity model influences simulation outcomes and whether any model exhibits superior performance.
Simulation results are presented through figures, displaying velocity, pressure, and viscosity values in specific regions of the domain for both shorter and longer simulation times. Additionally, forward and backward wave separation analysis was conducted during the longer simulations.
The results show that using a varying viscosity model had a damping effect on the velocity values, and the wave separation seemed to work slightly better when the varied viscosity model was used. However, no significant variations were observed in pressure values across the different viscosity models. While a definitive determination of the best-performing model could not be made, it is recommended to use a varying viscosity model to dampen the velocity values within the system. Notably, the Casson model demonstrated behaviour similar to that of constant viscosity and is therefore not recommended.